“The Palace of Fine Arts in Mexico City
has sunk more than 10 feet into the ground since it was built 60 years
ago and the most noticeable effect is that the grand stone stairway
has disappeared and the entrance is now at street level.”
C.B. Crawford,
Canadian Building Digest
Introduction
The principal function of a house is to provide protection from the elements. Our
present society, however, requires that a home provide not only shelter, but also
privacy, safety, and reasonable protection of our physical and mental health. A
living facility that fails to offer these essentials through adequately designed
and properly maintained interiors and exteriors cannot be termed “healthful housing.”
In this chapter, the home is considered in terms of the parts that have a bearing
on its soundness, state of repair, and safety. These are some of the elements that
the housing inspector must examine when making a thorough housing inspection.
Figure 6.1 shows a typical house being built and inspected today.
Click here for the key to Figure 6.1. Both
the figure and the key are available in an interactive format in the glossary on
the U.S. Inspect Web site [1].
Figure 6.2 shows a typical house built between 1950 and 1980.
Click here for the key to Figure 6.2. The figures
show the complexity and the numerous components of a home. These components form
the vocabulary that is necessary to discuss housing structure inspection issues.
Key to Figure
6.1
- Ash dump—A
door or opening in the firebox that leads directly to the ash pit, through which
the ashes are swept after the fire is burned out. All fireboxes are not equipped
with an ash dump.
- Attic space—The
open space within the attic area.
- Backfill—The
material used to refill an excavation around the outside of a foundation wall
or pipe trench.
- Baluster—One
of a series of small pillars that is attached to and runs between the stairs
and the handrails. The spacing between the balusters should be less than 4 inches
to prevent small children from getting stuck between the balusters. Balusters
are considered a safety item and provide an additional barrier.
- Baseboard trim—Typically
a wood trim board that is placed against the wall around the perimeter of a
room next to the floor. The intent is to conceal the joint between the floor
and wall finish.
- Basement window—A
window opening installed in the basement wall. Basement windows are occasionally
below the finish grade level and will be surrounded on the exterior by a window
well.
- Blind or shutter—A
lightweight frame in the form of a door located on each side of a window. They
are most commonly constructed of wood (solid or louvered panels) or plastic.
Originally they were designed to close and secure over the windows for security
and foul weather. Most shutters now are more likely decorative pieces that are
secured to the house beside the windows.
- Bridging—Small
pieces of wood or metal strapping placed in an X-pattern between the floor joists
at midspan to prevent the joists from twisting and squeaking and to provide
reinforcement and distribution of stress.
- Building paper/underlayment—Building
material, usually a felt paper that is used as a protective barrier against
air and moisture passage from the area beneath the flooring as well as providing
a movement/noise isolator in hardwood flooring.
- Ceiling joist—A
horizontally placed framing members at the ceiling of the top-most living space
of a house that provides a platform to which the finished ceiling material can
be attached.
- Chair rail
(not shown)—Decorative trim applied around the perimeter of a room such as a
formal dining room or kitchen/breakfast nook at the approximate same height
as the back of a chair. It is sometimes used as a cap trim for wainscoting (see
wainscoting).
- Chimney—A
masonry or in more modern construction wood framed enclosure that surrounds
and contains one or more flues and extends above the roofline.
- Chimney cap—The
metal or masonry protective covering at the top of the chimney that seals the
chimney shaft from water entry between the chimney enclosure and the flue tiles.
- Chimney flues—The
space or channel in a chimney that carries off the smoke and other combustion
gases to the outside air. Most homes will have a terra cotta tile flue or a
metal flue.
- Collar beam/tie—A
horizontal piece of framing lumber that provides intermediate support for opposite
rafters. They are usually located in the middle to upper third portion of the
rafters. It is also known as a collar beam or collar brace.
- Concrete slab floor—Typically
approximately 4 inches thick, the concrete slab floor provides a number of uses.
It creates a solid level surface to walk and work on. It provides a separation
between the grade/soil and a potentially livable area. It also provides lateral
compression resistance for the foundation walls, preventing soil pressure from
outside the foundation from pushing the foundation walls and footings inward.
- Corner brace—Diagonal
braces placed at the corners of framed walls to stiffen them and provide extra
strength.
- Cornice—An
overhang of a pitched roof at the eave line that usually consists of a fascia
board, a soffit, and any appropriate moldings or vents.
- Cornice molding—The
individual pieces of wood trim that are applied to the cornice area at the eaves.
- Door casing/trim—The
finish trim details around the perimeter of the door on the interior finished
wall.
- Door frame/jamb—The
top and sides of the door to include the wall framing as well as the actual
door frame and trim.
- Downspout—A
pipe, usually of metal or vinyl, that is connected to the gutters and is used
to carry the roof-water runoff down and away from the house.
- Downspout gooseneck—Segmented
section of downspout that is bent at a radius to allow the downspout to be attached
to the house and to follow the bends and curves of the eaves and ground.
- Downspout shoe—The
bottom downspout gooseneck that directs the water from the downspout to the
extension or splash block at the grade.
- Downspout strap—Strap
used to secure the downspout to the side of the house.
- Drain tile—A
tube or cylinder that is normally installed around the exterior perimeter of
the foundation footings that collects and directs ground water away from the
foundation of the house. The tile can be individual sections of clay or asphalt
tubing or, in more recent construction, a perforated-plastic drain tile that
is approximately 4 inches in diameter. The drain tile leads either towards a
sump or to an exterior discharge away from the house.
- Entrance canopy—A
small overhanging roof that shelters the front entrance.
- Entrance stoop—An
elevated platform constructed of wood framing or masonry at the front entry
that allows visitors to stand above or out of the elements. The platform should
be wide enough to allow someone to stand on the platform while opening an outward
swinging door such as a storm door even if one is not present.
- Exterior siding—The
decorative exterior finish on a house. Its primary function is to protect the
shell of the house from the elements. The choice of siding materials varies
widely to include wood, brick, metal, vinyl, concrete, stucco, and a variety
of manufactured compositions such as compressed wood, compressed cellulose (paper),
fiber-reinforced cement, and synthetic stucco.
- Fascia—The
visible flat front board that caps the rafter tail ends and encloses the overhang
under the eave that runs along the roof edge. The gutter is usually attached
at this location.
- Fascia/rake board—The
visible flat front board that caps the rafter tail ends and encloses the overhang
under the eave that runs along the roof edge and at the edge of the roofing
at the gables. The gutter is usually attached to this board at the eaves.
- Finish flooring—The
final floor covering inside the living space of a house. The most common types
of finishes are carpeting; hardwood flooring; ceramic, composite, or laminate
stone tile; parquet panels; or vinyl sheet flooring.
- Finished grade line—A
predetermined line indicating the proposed elevation of the ground surface around
a building.
- Firebox—The
cavity in the open face of the fireplace in which the fire is maintained. The
firebox leads directly to the fireplace flue. The firebox is constructed of
fire or refractory brick set in fireclay or reinforced mortar in traditional
masonry fireplaces. The firebox may also be constructed of metal or ceramic-coated
metal panels in more modern prefabricated fireplaces. The walls of the firebox
are usually slanted toward the living space both to direct smoke up toward the
flue and to reflect heat into the room.
- Fireplace cleanout door—The
access door to the ash pit beneath the fireplace. On a fireplace that is located
inside the house, the cleanout door is usually located in the lowest accessible
level of the house such as the basement or crawl space. On a fireplace that
is located at the outside of the house, the cleanout door will be located at
the exterior of the chimney. Not all fireplaces are equipped with a cleanout
door.
- Fireplace hearth—The
inner or outer floor of a fireplace, usually made of brick, tile, or stone.
- Flashing—The
building component used to connect and cover portions of a deck, roof, or siding
material to another surface such as a wall, a chimney, a vent pipe, or anywhere
that runoff is heavy or where two dissimilar materials meet. The flashing is
mainly intended to prevent water entry and is usually made of rubber, tar, asphalt,
or various metals.
- Floor joists—The
main subfloor framing members that support the floor span. Joists are usually
made of engineered wood I-beams or 2 x 8 or larger lumber.
- Foundation footing—The
base on which the foundation walls rests. The foundation is wider than the foundation
wall to spread out the load it is bearing and to help prevent settling.
- Foundation wall—The
concrete block, concrete slab or other nonwood material that extends below or
partly below grade, which provides support for exterior walls and other structural
pans of the building.
- Framing studs—A
2 x 4 or 2 x 6 vertical framing member used to construct walls and partitions,
usually spaced 12 to 24 inches apart.
- Gable framing—The
vertical and horizontal framing members that make up and support the end of
a building as distinguished from the front or rear side. A gable is the triangular
end of an exterior wall above the eaves.
- Garage door—The
door for the vehicle passage into the garage area. Typical garage doors consist
of multiple jointed panels of wood, metal, or fiberglass.
- Girder—A
large beam supporting floor joists at the same level as the sills. A larger
or principal beam used to support concentrated loads at isolated points along
its length.
- Gravel fill—A
bed of coarse rock fragments or pebbles that is laid atop the existing soil
before pouring the concrete slab. The gravel serves a dual purpose of breaking
surface tension on the concrete slab and providing a layer that interrupts capillary
action of subsurface moisture from reaching the concrete slab. Typically, a
polyethylene sheeting will be installed between the gravel fill and the concrete
slab for further moisture proofing.
- Gutter—A
channel used for carrying water run-off. Usually located at the eaves of a house
and connected to a downspout. The primary purpose of the gutters and downspouts
is to carry roof water run-off as far away from the house as possible.
- Insulation—A
manufactured or natural material that resists heat flow that is installed in
a house’s shell to keep the heat in a house in the winter and the coolness in
the house in the summer. The most common form of insulation is fiberglass, whether
in batts or blown-in material, along with cellulose, rigid foam boards, sprayed-in
foam, and rock wool.
- Jack/king stud—The
framing stud, sometimes called the trimmer, that supports the header above a
window, door, or other opening within a bearing wall. Depending on the size
of the opening, there may be several jack studs on either side of the opening.
- Mantel—The
ornamental or decorative facing around a fireplace including a shelf that is
attached to the breast or backing wall above the fireplace.
- Moisture/vapor barrier—A
nonporous material, such as plastic or polyethylene sheeting, that is used to
retard the movement of water vapor into walls and attics and prevent condensation
in them. A vapor barrier is also installed in crawl space areas to prevent moisture
vapor from entering up through the ground.
- Newel post—The
post at the top and bottom of the handrails and anywhere along the stair run
that creates a directional change in the handrails is called the newel post.
The newel post is securely anchored into the underlying floor framing or the
stair stringer to provide stability to the handrails.
- Reinforcing lath—A
strip of wood or metal attached to studs and used as a foundation for plastering,
slating or tiling. Lath has been replaced by gypsum board in most modern construction.
- Ridge board/beam—The
board placed on edge at the top-most point of the roof framing, into which the
upper ends of the rafters are joined or attached.
- Roofing—The
finished surface at the top of the house that must be able to withstand the
effects of the elements (i.e., wind, rain, snow, hail, etc.). A wide variety
of materials are available, including asphalt shingles, wood shakes, metal roofing,
ceramic and concrete tiles, and slate, with asphalt shingles making up the bulk
of the material used.
- Roof rafters—Inclined
structural framing members that support the roof, running from the exterior
wall the to the ridge beam. Rafters directly support the roof sheathing and
create the angle or slope of the roof.
- Roof sheathing—The
material used to cover the outside surface of the roof framing to provide lateral
and rack support to the roof, as well as to provide a nailing surface for the
roofing material. This material most commonly consists of plywood OSB or horizontally
laid wood boards.
- Sidewalk—A
walkway that provides a direct, all-weather approach to an entry. The sidewalk
can be constructed of poured concrete, laid stone, concrete pavers, or gravel
contained between borders or curbs.
- Sill plate—The
horizontal wood member that is anchored to the foundation masonry to provide
a nailing surface for floors or walls built above.
- Silt fabric—A
porous fabric that acts as a barrier between the backfilled soil (see backfill)
and the gravel surrounding the drain tile. This barrier prevents soil particles
from blocking the movement of groundwater to the drain tile.
- Soffit/lookout block—Rake
cross-bracing between the fly rafters and end gable rafters that the soffit
is nailed to.
- Stair rail—A
sturdy handhold and barrier that follows the outside, and sometimes inside,
perimeter of the stairs. The stair rail is used to prevent falls and to provide
a means of additional support when walking up or down the stairs.
- Stair riser—The
vertical boards that close the space between each stair tread on a set of stairs
(see stair stringer and stair tread).
- Stair stringer—The
supporting members in a set of stairs that are cut or notched to accept the
individual treads and risers (see stair riser and stair tread).
- Stair tread—The
horizontal board in a stairway that is walked upon (see stair riser and
stair stringer).
- Subfloor—Boards
or plywood, installed over joists, on which the finish floor rests.
- Support post—A
vertical framing member usually designed to carry or support a beam or girder.
In newer construction a metal lally (pronounced “lolly”) column is commonly
used, as well as 4 x 4- or 6 x 6-inch wood posts.
- Tar—Otherwise
known as asphalt, tar is a very thick, dark brown/black substance that is used
as a sealant or waterproofing agent. It is usually produced naturally by the
breakdown of animal and vegetable matter that has been buried and compressed
deep underground. Tar is also manufactured—a hydrocarbon by-product or residue
that is left over after the distillation of petroleum. It is commonly used as
a sealant or patch for roof penetrations, such as plumbing vents and chimney
flashing. Tar is also used as a sealer on concrete and masonry foundation walls
before they have been backfilled.
- Termite shield—A
metal flashing that is installed below the sill plate that acts as a deterrent
to keep termites from reaching the sill plate.
- Top plate—The
topmost horizontal framing members of a framed wall. Most construction practices
require the top plate to be doubled in thickness.
- Wainscoting—The
wooden paneling of the lower part of an interior wall up to approximately waist-height
or between 36 and 48 inches from the floor.
- Wall insulation—A
manufactured or natural material that resists heat flow that is installed in
a house’s shell to keep the heat in a house in the winter and the coolness in
the house in the summer. Fiberglass batts are the most common form of wall insulation.
- Wall sheathing—The
material used to cover the outside surface of the wall framing that provides
lateral and shear support to the wall as well as a nailing surface for the exterior
siding.
- Window casing/trim—The
finish trim details around the perimeter of the window on the interior finished
wall.
- Window cripple—Short
studs placed between the header and a top plate or between a sill and sole plate.
- Window frame/jamb—The
top and sides of the window, to include the wall framing and the actual window
frame and trim.
- Window header—A
beam placed perpendicular to wall studs above doors, windows, or other openings
to carry the weight of structural loads above the window or door.
- Window sash—The
framework that holds the glass in a door or window.
- Window well
(not shown)—An excavation around a basement window that prevents the surrounding
soils from collapsing into the window. The window well surround is normally
constructed of formed corrugated galvanized metal, built-up masonry, or pressure-treated
wood.
Key to Figure 6.2
Fireplace
- Chimney—A
vertical masonry shaft of reinforced concrete or other approved noncombustible,
heat resisting material enclosing one or more flues. It removes the products
of combustion from solid, liquid or gaseous fuel.
- Flue liner—The
flue is the hole in the chimney. The liner, made of terra cotta or metal, protects
the brick from harmful smoke gases.
- Chimney cap—This
top is generally of concrete. It protects the brick from weather.
- Chimney flashing—Sheet
metal flashing provides a tight joint between chimney and roof.
- Firebrick—An
ordinary brick cannot withstand the heat of direct fire, and so special firebrick
is used to line the fireplace. In newer construction, fireplaces are constructed
of prefabricated metal inserts.
- Ash dump—A
trap door to let the ashes drop to a pit below, where they may be easily removed.
- Cleanout door—The
door to the ash pit or the bottom of a chimney through which the chimney can
be cleaned.
- Chimney breast—The
inside face or front of a fireplace chimney.
- Hearth—The
floor of a fireplace that extends into the room for safety purposes.
Roof
- Ridge—The
top intersection of two opposite adjoining roof surfaces.
- Ridge board—The
board that follows along under the ridge.
- Roof rafters—The
structural members that support the roof.
- Collar beam—Not
a beam at all; this tie keeps the roof from spreading and connects similar rafters
on opposite sides of the roof.
- Roof insulation—An
insulating material (usually rock wool or fiberglass) in a blanket form placed
between the roof rafters to keep a house warm in the winter and cool in the
summer.
- Roof sheathing—The
boards that provide the base for the finished roof. In newer construction, roof
sheathing is composed of sheets of plywood, or oriented strand board (OSB).
- Roofing—The
wood, asphalt or asbestos shingles—or tile, slate, or metal—that form the outer
protection against the weather.
- Cornice—A
decorative element made of molded members, usually placed at or near the top
of an exterior or interior wall.
- Gutter—The
trough that gathers rainwater from a roof.
- Downspout—The
pipe that leads the water down from the gutter.
- Storm sewer tile—The
underground pipe that receives the water from the downspouts and carries it
to the sewer. In newer construction, plastic-type material have replaced tile.
- Gable—The
triangular end of a building with a sloping roof.
- Barage board—The
fascia or board at the gable just under the edge of the roof.
- Louvers—A
series of slanted slots arranged to keep out rain, yet allow ventilation.
Walls and Floors
- Corner post—The
vertical member at the corner of the frame, made up to receive inner and outer
covering materials.
- Studs—The
vertical wood members of the house, usually 2 x 4s at minimum and spaced every
16 inches.
- Sill—The
board that is laid first on the foundation, and on which the frame rests.
- Plate—The
board laid across the top ends of the studs to hold them even and tight.
- Corner bracing—Diagonal
strips to keep the frame square and plumb.
- Sheathing—The
first layer of outer wall covering nailed to the studs.
- Joist—The
structural members or beams that hold up the floor or ceiling, usually 2 x 10s
or 2 x 12s spaced 16 inches apart.
- Bridging—Cross-bridging
or solid. Members at the middle or third points of joist spans to brace one
to the next and to prevent their twisting.
- Subflooring—Typically
plywood or particle wood that is laid over the joists.
- Flooring paper—A
felt paper laid on the rough floor to stop air infiltration and, to some extent,
noise.
- Finish flooring—Hardwood,
of tongued and grooved strips, carpet, or vinyl products (tile, linoleum).
- Building paper or sheathing—Paper
or plasticized material placed outside the sheathing, not as a vapor barrier,
but to prevent water and air from leaking in. Building paper is also used as
a tarred felt under shingles or siding to keep out moisture or wind.
- Beveled siding—Sometimes
called clapboards, with a thick butt and a thin upper edge lapped to shed water.
In newer construction, vinyl, aluminum, or fiber cement siding and stucco are
more prevalent.
- Wall insulation—A
blanket of wool or reflective foil placed inside the walls.
- Metal lath—A
mesh made from sheet metal onto which plaster or other composite surfacing materials
can be applied. In newer construction, plaster sheetrock 4 x 8-foot sheets have
replaced lath.
Foundation and Basement
- Finished grade line—The
top of the ground at the foundation.
- Foundation wall—The
wall of poured concrete (shown) or concrete blocks that rests on the footing
and supports the remainder of the house.
- Termite shield—A
metal baffle to prevent termites from entering the frame.
- Footing—The
concrete pad that carries the entire weight of the house upon the earth.
- Footing drain tile—A
pipe with cracks at the joints, or perforated plastic pipe to allow underground
water to drain away before it gets into the basement.
- Basement floor slab—The
4- or 5-inch layer of concrete that forms the basement floor.
- Gravel fill—Placed
under the slab to allow drainage and to guard against a damp floor.
- Girder—A
main beam upon which floor joists rest. Usually of steel, but also of wood.
- Backfill—Earth,
once dug out, that has been replaced and tamped down around the foundation.
- Areaway—An
open space to allow light and air to a window. Also called a light well.
- Area wall—The
wall, of metal or concrete, that forms the open area.
Windows and Doors
- Window—An
opening in a building for admitting light and air. It usually has a pane or
panes of glass and is set in a frame or sash that is generally movable for opening
and shutting.
- Window frame—The
lining of the window opening.
- Window sash—The
inner frame, usually movable, that holds the glass.
- Lintel—The
structural beam over a window or door opening.
- Window casing—The
decorative strips surrounding a window opening on the inside.
Stairs and Entry
- Entrance canopy—A
roof extending over the entrance door.
- Furring—Falsework
or framework necessary to bring the outer surface level to the inner surface.
- Stair tread—The
horizontal part of a step that the foot hits when climbing up or down the stairs.
- Stair riser—The
vertical board connecting one tread to the next.
- Stair stringer—The
sloping board that supports the ends of the steps.
- Newel—The
post that terminates the railing.
- Stair rail—The
bar used for a handhold when using the stairs.
- Balusters—Vertical
rods or spindles supporting a rail.
Foundation
The word “foundation” is used to mean
- construction below grade, such as footings,
cellar, or basement;
- the composition of the earth on which the
building rests; and
- special construction, such as pilings and
piers used to support the building.
The foundation bed may be composed of solid rock,
sand, gravel, or unconsolidated sand or clay. Rock, sand, or gravel are the most
reliable foundation materials.
Figure 6.3 shows the three most common foundations for homes. Unconsolidated
sand and clay, though found in many sections of the country, are not as desirable
for foundations because they are subject to sliding and settling [1].
Capillary breaks have been identified as a key way of reducing moisture incursion
in new construction [3].
The footing distributes the weight of the building over a sufficient area of ground
to ensure that the foundation walls will stand properly. Footings are usually concrete;
however, in the past, wood and stone have been used. Some older houses were constructed
without footings.
Although it is usually difficult to determine the condition of a footing without
excavating the foundation, a footing in a state of disrepair or lack of a footing
will usually be indicated either by large cracks or by settlement in the foundation
walls. This type of crack is called a “Z” crack.
Foundation wall cracks are usually diagonal, starting from the top, the bottom,
or the end of the wall
Figure 6.4. Cracks that do not extend to at least one edge of the wall may
not be caused by foundation problems. Such wall cracks may be due to other structural
problems and should also be reported.
The foundation walls support the weight of the structure and transfer this weight
to the footings. The foundation walls may be made of stone, brick, concrete, or
concrete blocks. The exterior should be moisture proofed with either a membrane
of waterproof material or a coating of portland cement mortar. The membrane may
consist of plastic sheeting or a sandwich of standard roofing felt joined and covered
with tar or asphalt. The purpose of waterproofing the foundation and walls is to
prevent water from penetrating the wall material and leaving the basement or cellar
walls damp.
Holes in the foundation walls are common in many old houses. These holes may be
caused by missing bricks or blocks. Holes and cracks in a foundation wall are undesirable
because they make a convenient entry for rats and other rodents and also indicate
the possibility of further structural deterioration. Basement problems are a major
complaint of homeowners [4,5,6,7,8,9]
Concrete is naturally porous (12%–18% air). When
it cures, surplus water creates a network of interconnected capillaries. These pores
let in liquid water, water vapor, and radon gas. Like a sponge, concrete draws water
from several feet away. As concrete ages, the pores get bigger as a result of freezing,
thawing, and erosion.
Concrete paints, waterproofing sealers, or cement coatings are a temporary fix.
They crack or peel and cannot stop gases such as water vapor and radon.
Damp basement air spreads mold and radon through the house. Efflorescence (white
powder stains) and musty odors are telltale signs of moisture problems. Basement
remodeling traps invisible water vapor, causing mold and mildew. Most basements
start leaking within 10 to 15 years. The basement walls and floors should be sealed
and preserved before they deteriorate. The basement floor should be concrete placed
on at least 6 inches of gravel. The gravel distributes groundwater movement under
the concrete floor, reducing the possibility of the water penetrating the floor.
A waterproof membrane, such as plastic sheeting, should be laid before the concrete
is placed for additional protection against flooding and the infiltration of radon
and other gases.
The basement floor should be gradually, but uniformly, sloped from all directions
toward a drain or a series of drains. These drains permit the basement or cellar
to drain if it becomes flooded.
Water or moisture marks on the floor and walls are signs of ineffective waterproofing
or moisture proofing. Cellar doors, hatchways, and basement windows should be weather-tight
and rodent-proof. A hatchway can be inspected by standing at the lower portion with
the doors closed; if daylight can be seen, the door needs to be sealed or repaired.
Vapor Barriers
Crawl Space Vapor Barriers
Throughout the United States, even in desert areas, there is moisture in the ground
from groundwater being absorbed. Even in an apparently dry crawl space, a large
amount of water is entering. The moisture is drying out as fast as it is entering,
which causes high moisture levels in the crawl space and elsewhere in the house.
A solid vapor barrier is recommended in all crawl spaces and should be required
if moisture problems exist [10]. This vapor barrier,
if properly installed, also reduces the infiltration of radon gas. Of course, if
the moisture is coming from above ground, a vapor barrier will collect and hold
the moisture. Therefore, any source of moisture must be found and eliminated. The
source may be as obvious as sweating pipes, or may be more difficult to spot, such
as condensation on surfaces. The solution can be as simple as applying insulation
to exposed sections of the piping or complex enough to require power exhaust fans
and the addition of insulation and vapor barriers.
The more common causes of moisture problems in a new home are moisture trapped within
the structure during construction and a continuing source of excess moisture from
the basement, crawl space, or slab. To resolve this potential problem, 6-mil plastic
sheets should be laid as vapor barriers over the entire crawl space floor. The sheets
should overlap each other by at least 6 inches and should be taped in place. The
plastic should extend up the perimeter walls by about 6 inches. The plastic sheets
should be attached to the interior walls of the crawl space with mastic or batten
strips. All of the perimeter walls should be insulated, and insulation should be
between the joists at the top of the walls. Vents, which may need to be opened in
the late spring and closed in the fall, should not be blocked. If not properly managed,
moisture originating in the crawl space can cause problems with wood flooring and
create many biologic threats to health and property. A properly placed vapor barrier
can prevent or reduce problem moisture from entering the home.
Vapor Barriers for Concrete Slab Homes
Strip flooring and related products should be protected from moisture migration
by a slab. Proper on-grade or above-grade construction requires that a vapor barrier
be placed beneath the slab. Moisture tests should be done to determine the suitability
of the slab before installing wood products. A vapor barrier equivalent to 4- or
6-mil polyethylene should be installed on top of the slab to further protect the
wood products and the residents of the home.
Wall and Ceiling Vapor Barriers
Wall and ceiling vapor barriers should go on the heated side of the insulation and
are necessary in cold climates. Water vapor flows from areas of high pressure (indoors
in winter) through the wall to an area of low pressure (outdoors in winter). People
and their pets produce amazing quantities of water vapor by breathing. Additional
moisture in considerable quantities is created in the home from everyday activities
such as washing clothes, cooking, and personal hygiene. The purpose of the vapor
barrier is to prevent this moisture from entering the wall and freezing, then draining,
causing damage. In addition, wet insulation has very little insulating value. Insulation
with the vapor barrier misplaced will allow the vapor to condense in the insulation
and then freeze. In cold climates, this ice can actually build up all winter and
run out on the floor in the spring. Such moisture buildup blisters paint, rots sheathing,
and destroys the insulating value of insulation.
House Framing
Many types of house-framing systems are found in various sections of the country;
however, most framing systems include the elements described in this section.
Foundation Sills
The purpose of the sill is to provide support or a bearing surface for the outside
walls of the building. The sill is the first part of the frame to be placed and
rests directly on the foundation wall. It is often bolted to the foundation wall
by sill anchors. In many homes, metal straps are cemented into the foundation wall
that are bent around and secured to the sill. It is good practice to protect the
sill against termites by extending the foundation wall to at least 18 inches above
the ground and using a noncorroding metal shield continuously around the outside
top of the foundation wall.
Flooring Systems
The flooring system is composed of a combination of girders, joists, subflooring,
and finished flooring that may be made up of concrete, steel, or wood. Joists are
laid perpendicular to the girders, at about 16 inches on center, and the subflooring
is attached to them. If the subfloor is wood, it may be nailed, glued, or screwed
at either right angles or diagonally to the joists. Many homes are built with wood
I-joists or trusses rather on than solid wood joists.
In certain framing systems, a girder supports the joists and is usually a larger
section than the joists it supports. Girders are found in framing systems where
there are no interior bearing walls or where the span between bearing walls is too
great for the joists. The most common application of a girder is to support the
first floor. Often a board known as a ledger is applied to the side of a wood girder
or beam to form a ledge for the joists to rest upon. The girder, in turn, is supported
by wood posts or steel “lally columns” that extend from the cellar or basement floor
to the girder.
Studs
For years, wall studs were composed of wood and were 2 x 4 inches; but, with the
demand for greater energy efficiency in homes, that standard no longer holds true.
Frame studs up to 6 inches wide are used to increase the area available for placing
insulation material. The increased size in the studs allow for larger spaces between
joists.
There are now alternatives to conventional wood studs, specifically, insulated concrete
forms, structural insulated panels, light-gauge steel, and combined steel and wood
[11,12,13]. The
advantages of light-gauge steel include the following:
- weighs 60% less than equivalent wood units
and has greater strength and durability;
- is impervious to termites and other damage
causing pests;
- stays true and does not warp;
- is noncombustible; and
- is recyclable.
The disadvantages of steel include these:
- steel is an excellent thermal conductor and
requires additional external insulation;
- as a new product, it is unfamiliar to craftsmen,
engineers, and code officials; and
- a different type of construction tools are
required.
The combined steel and wood framing system includes
light-gauge steel studs with 6 inch wooden stud pieces attached to the top and bottom
to allow easy attachment to traditional wood frame materials.
There are two types of walls or partitions: bearing and nonbearing. A bearing wall
is constructed at right angles to support the joists. A nonbearing wall, or partition,
acts as a screen or enclosure; hence, the headers in it are often parallel to the
joists of the floor above.
In general, studs, like joists, are spaced 16 inches on center. In light construction,
such as garages and summer cottages, wider spacing on studs is common.
Openings for windows or doors must be framed in studs. This framing consists of
horizontal members (headers) and vertical members (trimmers or jack studs).
Because the vertical spaces between studs can act as flues to transmit flames in
the event of a fire, fire stops are important in preventing or retarding fire from
spreading through a building by way of air passages in walls, floors, and partitions.
Fire stops are wood obstructions placed between studs or floor joists to block fire
from spreading in these natural flue spaces.
Interior Walls
Many types of materials are used for covering interior walls and ceilings, but the
principal type is drywall. The generic term “drywall” is typically used when talking
about gypsum board. It is also called wallboard or referred to by the brand name
Sheetrock. Gypsum board is a sheet material composed of a gypsum filler faced with
paper. In drywall construction, gypsum boards are fastened to the studs either vertically
or horizontally and then painted. The edges along the length of the sheet are slightly
recessed to receive joint cement and tape.
Drywall finish, composed of gypsum board, is a material that requires little, if
any, wait for application. Other drywall finishes include plywood, fiberboard, or
wood in various sizes and forms. Plaster was once quite popular for interior walls.
Plaster is a mixture (usually of lime, sand, and water) applied in two or three
coats to lath to form a hard-wall surface. A plaster finish requires a base on which
plaster can be spread. Wood lath at one time was the plaster base most commonly
used, but today gypsum-board lath is more popular. Gypsum lath may be perforated
to improve the bond and thus lengthen the time the plaster can remain intact when
exposed to fire. Building codes in some cities require that gypsum lath be perforated.
Expanded-metal lath also may be used as a plaster base. Expanded-metal lath consists
of sheet metal slit and expanded to form openings to hold the plaster. Plaster is
applied over the base to a minimum thickness of ½ inch. Because wood-framing members
may dry after the house is completed, some shrinkage can be expected, which, in
turn, may cause plaster cracks to develop around openings and in corners. Strips
of lath embedded in the plaster at these locations prevent cracks. Bathrooms have
unique moisture exposure problems and local code approved cement board should be
used around bath and shower enclosures.
Stairways
The purpose of stairway dimension standards is to ensure adequate headroom and uniformity
in riser and tread size.
Interior stairways (Figure
6.5) should be no less than 44 inches wide. The width of a stairway may
be reduced to 36 inches when permitted by local or state code in one- and two-family
dwellings. Stairs with closed risers should have maximum risers of 8¼ inches and
minimum treads of 9 inches plus 1 inch nosing. Basement stairs are often constructed
with open risers. These stairs should have maximum risers of 8¼ inches and minimum
treads of 9 inches plus 1-inch nosing. The headroom in all parts of the stair enclosure
should be no less than 80 inches. Dimensions of exterior stairways should be the
same as those of interior stairways, except that the headroom requirement does not
apply.
Staircases should have handrails that are between 1¼ and 2⅝ inches wide, particularly
if the staircases have more than four steps. Handrails should be shaped so they
can be readily grasped for safety and placed so they are easily accessible. Handrails
should be 4⅛ inches from the wall and be 34 to 38 inches above the leading edge
of the stairway treads. Handrails should not end in any manner or have projections
that can snag clothing.
Windows
The six general classifications of windows (Figure
6.6) are as follows [1]:
- Double-hung sash windows that move
up or down, balanced by weights hung on chains, ropes, or springs on each side;
- Casement
sash windows that are hinged at the side and can be hung so they will swing
out or in;
- Awning
windows that usually have two or more glass panes that are hinged at the top
and swing out horizontally;
- Sliding
windows that usually have two or more glass panes that slide past one another
on a horizontal track;
- Fixed windows
that are generally for increased light entry and decorative effect; and
- Skylight
windows for increased room illumination and decoration that can
be built to open.
The principal parts of a window, shown in three-dimensional
view in
Figure 6.7 and face-on and side view in
Figure 6.8, are the following:
Drip cap—A separate piece of wood projecting over the top of the window;
a component of the window casing. The drip cap protects against moisture.
Window trough—The cut or groove in which the sash of the window slides or
rests.
Window sill—The shelf on the bottom edge of a window, either a projecting
part of the window frame or the bottom of the wall recess that the window fits into.
The sill contains the trough and protects against moisture.
Recent technological advancements—new materials, coatings, design, and construction
features—make it possible to choose windows that allow you to balance winter heating
and summer cooling needs without sacrificing versatility or style. To ensure that
windows, doors, or skylights selected are appropriate for the region in which they
are to be installed, Energy Star Certification labels include a climate region map.
Some window glass is made of tempered glass to resist breakage. Some windows are
made of laminated glass, which resists breakage, but if broken produces glass shards
too small to cause injury [14]. The glazing, or glass,
can be a solid glass sheet (single glazed) or have two layers of glass (double glazed)
separated by a spacer. Air trapped between the glass layers provides some insulation
value. Triple-glazed windows have three pieces of glass, or two layers of glass
with a low emissivity film suspended between them. Triple-glazed windows have advantages
where extremes in weather and temperature are the norm. They also can reduce sound
transmission to a greater degree than can single- or double-glazed windows.
Doors
There are many styles of doors both for exterior and interior use. Exterior doors
must, in addition to offering privacy, protect the interior of the structure from
the elements. Various parts of a door are the same as the corresponding parts of
a window. A door’s function is best determined by the material from which it is
made, how it looks, and how it operates. When doors are used for security, they
are typically made from heavy materials and have durable, effective locks and hinges.
A door that lets in light or allows people to look out onto the yard, such as a
sliding glass door or a french door, will have multiple panes (also called lights)
or be made almost completely of glass.
Houses have many exterior and interior door options. Exterior doors are typically
far sturdier than interior doors and need to be weather tight and ensure security
for the home. Exterior doors are also more decorative than most interior doors and
may cost a considerable amount. Typical exterior doors include front entry doors,
back doors, french doors, dutch doors, sliding glass doors, patio doors, and garage
doors.
French doors and sliding doors are examples of the two primary ways doors open.
French doors swing on hinges; sliding doors glide along a track. Some doors, such
as dutch doors, have tops and bottoms that swing open independently.
Most doors are made of wood or materials made to look like wood. Fiberglass composite
and steel doors often have polymer or vinyl coatings embossed with wood grain; some
even have cellulose-based coatings that can be stained like wood doors. Wood doors
are made from every kind of wood imaginable, hardwoods being the most durable and
elegant. Wood doors insulate better than glass; composite and steel doors provide
even more insulation and durability, as well as better security than does wood.
Garage Doors
Garage doors open in almost any configuration needed for the design of the home.
Installing most garage doors is complex and dangerous enough that only a building
professional should attempt it. Garage doors often include very strong springs that
can come loose and severely injure the unsuspecting installer. Garage door springs
are under extreme tension because of the heavy loads they must lift, which makes
them dangerous to adjust. A garage door may suffer from any of several problems.
The most common problem is that the door becomes difficult to lift and lower. This
may be something that can be resolved with simple adjustments, or it may be more
serious. If the door is connected to an electric opener, the opener mechanism can
be disconnected from the door by pulling the release cord or lever. If the door
then works manually, the problem is with the electric opener. A door that seems
unusually hard to lift may have a problem with spring tension. Wood doors should
be properly painted or stained both outside and inside. If only the outside of a
garage door is finished, the door may warp and moisture may cause the paint to peel.
Rules issued by the Consumer Product Safety Commission on December 3, 1992, specify
entrapment protection requirements for garage doors [15].
The rules require that residential garage door openers contain one of the following:
- An external entrapment protection device,
such as an electric eye that sees an object obstructing the door without having
actual contact with the object. A door-edge sensor is a similar device. The
door-edge sensor acts much like the door-edge sensors on elevator doors.
- A constant contact control button, which is
a wall-mounted button requiring a person to hold in the control button continuously
for the door to close completely. If the button is released before the door
closes, the door reverses and opens to the highest position.
- A sticker on all newly manufactured garage
door openers warning consumers of the potential entrapment hazard. The sticker
is to be placed near the wall-mounted control button.
The variety of exterior door systems has increased
significantly over the past 5 to 10 years. Many combine several different materials
to make a realistic, if not actual wood, door that provides both beauty and enhanced
security.
Exterior House Doors
Exterior door frames are ordinarily of softwood plank, with the side rabbitted to
receive the door in the same way as casement windows. At the foot is a sill, made
of hardwood or other material, such as aluminum, to withstand the wear of traffic
and sloped down and out to shed water. Doors often come equipped with door sweeps
to conserve energy.
The four primary categories of modern exterior doors are steel, fiberglass, composites,
and wood.Steel—The
most common exterior door sold today is steel. Humidity will not cause a steel door
to warp or twist. Steel doors often have synthetic wood-grain embossed finishes
that accept stain. Just about every steel exterior door is filled with some type
of foam. This foam allows the doors to achieve R-values almost five times that of
an ordinary wood door. Metal is often used as a veneer frame. In general, the horizontal
members are called rails and the vertical members are called stiles. Every door
has a top and bottom rail, and some may have intermediate rails. There are always
at least two stiles, one on each side of the door.
Fiberglass—The second most frequently selected exterior door is fiberglass.
Fiberglass doors are similar to steel doors, but tend to be much more resistant
to denting. (Steel doors can be dented quite easily.) Fiberglass doors also are
stainable and have rich, realistic wood graining. Fiberglass doors are insulated
with foam and have high R-values.
Composite materials—The third most common exterior door is made of composite
materials. These doors often are of two materials blended together. Their composite
fiber-reinforced core can be twice as strong as wood. This composite core will not
rot, warp, or twist when subjected to high levels of humidity.
Wood—The last major category of doors is wood. Solid wood doors range from
inexpensive to true works of art. Their downside is that they can warp and bow if
not sealed properly from humidity and will then fit poorly in their frames.
Other types of wooden doors are described below.
- Batten doors
are often found on older homes. They are made of boards nailed together in various
ways. The simplest is two layers nailed to each other at right angles, usually
with each layer at 45° to the vertical. Another type of batten door consists
of vertical boards nailed at right angles to several (two to four) cross strips
called ledgers, with diagonal bracing members nailed between the ledgers. If
vertical members corresponding to ledgers are added at the sides, the verticals
are called frames. Batten doors are often found in cellars and other places
where appearance is not a factor and economy is desired.
- Solid flush doors
are perfectly flat, usually on both sides, although occasionally they are made
flush on one side and are paneled on the other. Flush doors sometimes are solid
planking, but they are commonly veneered and possess a core of small pieces
of white pine or other wood. These pieces are glued together with staggered
end joints. Along the sides, top, and bottom are glued ¾-inch edge strips of
the same wood, used to create a smooth surface that can be cut or planed. The
front and back faces are then covered with a ⅛-inch to ¼-inch layer of veneer.
Solid flush doors may be used on both the interior and exterior.
- Hollow-core doors,
like solid flush doors, are perfectly flat; but, unlike solid doors, the core
consists mainly of a grid of crossed wooden slats or some other type of grid
construction. Faces are three-ply plywood instead of one or two plies of veneer,
and the surface veneer may be any species of wood, usually hardwood. The edges
of the core are solid wood and are made wide enough at the appropriate places
to accommodate locks and butts. Doors of this kind are considerably lighter
than solid flush doors. Hollow-core doors are usually used as interior doors.
Many doors are paneled, with most panels consisting
of solid wood or plywood, either raised or flat, although exterior doors frequently
have one or more panels of glass. One or more panels may be used, although some
have as many as nine panels. Paneled doors may be used both on the interior or exterior.
The frame of a doorway is the portion to which the door is hinged. It consists of
two side jambs and a head jamb, with an integral or attached stop against which
the door closes.
Roof Framing
Rafters
One of a series of structural roof members spanning from an exterior beam or a ridge
board. Rafters serve the same purpose for the roof as joists do for floors, that
is, providing support for sheathing and roofing material. They are typically placed
on 16 inch centers.
Collar Beam
Collar beams are ties between rafters on opposite sides of the roof. If the attic
is to be used for rooms, the collar beam may double as the ceiling joist.
Purlin
A purlin is the horizontal member that forms the support for the rafters at the
intersection of the two slopes of a gambrel roof.
Ridge Board
A ridge board is a horizontal member that forms a lateral tie to make rafters secure.
Hip
A hip is like a ridge, except that it slopes. It is the intersection of two adjacent,
rather than two opposite, roof planes.
Roof Sheathing
The manner in which roof sheathing is applied depends upon the type of roofing material.
Roof boards may vary from tongue-and-groove lumber to plywood panels.
Dormer
The term “dormer window” is applied to all windows in the roof of a building, whatever
their size or shape.
Roofs
Asphalt Shingle
The principal damage to asphalt shingle roofs is caused by strong winds on shingles
nailed close to the ridge line of the roof. Usually the shingles affected by winds
are those in the four or five courses nearest the ridge and in the area extending
about 5 feet down from the edge or rake of the roof.
EPDM
Ethylene propylene diene monomer (EPDM) is a single-ply roofing system. EPDM allows
extreme structural movement without splitting or cracking and retains its pliability
in a wide range of temperatures.
Asphalt Built-up Roofs
Asphalt roofs may be unsurfaced (a coating of bitumen being exposed directly to
the weather) or surfaced (with slag or gravel embedded in the bituminous coating).
Using surfacing material is desirable as a protection against wind damage and the
elements. This type of roof should have enough pitch to drain water readily.
Coal Tar Pitch Built-up Roofs
This type of roof must be surfaced with slag or gravel. A coal tar pitch built-up
roof should always be used on a deck pitched less than ½ inch per foot; that is,
where water may collect and stand. This type of roof should be inspected on completion,
6 months later, and then at least once a year, preferably in the fall. When the
top coating of bitumen shows damage or has become badly weathered, it should be
renewed.
Slate Roofs
The most common problem with slate roofs is the replacement of broken slates. Otherwise,
slate roofs normally render long service with little or no repair.
Tile Roofs
Replacement of broken shingle tiles is the main maintenance problem with tile roofs.
This is one of the most expensive roofing materials. It requires very little maintenance
and gives long service.
Copper Roofs
Usually made of 16-ounce copper sheeting and applied to permanent structures, copper
roofs require practically no maintenance or repair when properly installed. Proper
installation allows for expansion and contraction with changes in temperature.
Galvanized Iron Roofs
The principal maintenance for galvanized iron roofs involves removing rust and keeping
the roof well painted. Leaks can be corrected by renailing, caulking, or replacing
all or part of the sheet or sheets in disrepair.
Wood Shingle Roofs
The most important factors of wood shingle roofs are their high pitch and exposure,
the character of wood, the kind of nails used and the preservative treatment given
the shingles. At one time these roofs were treated with creosote and coal tar preservatives.
Because they are made from a flammable material, insurance companies frequently
have higher rates for wood shingle roofs.
Roof Flashing
Valleys in roofs (such as gambrel roofs, which have two pitches designed to provide
more space on upper floors and are steeper on their lower slope and flatter toward
the ridge) that are formed by the junction of two downward slopes may be open or
closed. In a closed valley, the slates, tiles, or shingles of one side meet those
of the other, and the flashing below them may be comparatively narrow. In an open
valley, the flashing, which may be made of zinc, copper, or aluminum, is laid in
a continuous strip, extending 12 to 18 inches on each side of the valley, while
the tiles or slates do not come within 4 to 6 inches of it. The ridges built up
on a sloping roof where it runs down against a vertical projection, like a chimney
or a skylight, should be weatherproofed with flashing. Failure of roof flashing
is usually due to exposed nails that have come loose. The loose nails allow the
flashing to lift, resulting in leakage. Flashings made of lead or coated with lead
should not be used.
The use of a thin, self-sticking rubber ice and water shield under flashings and
on the edge of roofs is now common practice. The shield helps reduce leakage and
ice backup in cold climates, preventing serious damage to this part of the home.
Gutters and Leaders
Gutters and leaders should be of noncombustible materials and should not be made
of lead, lead-coated copper, or any other formulation containing lead. They should
be securely fastened to the structure and spill into a storm sewer, not a sanitary
sewer, if the neighborhood has one. When there is no storm sewer, a concrete or
stone block placed on the ground beneath the leader prevents water from eroding
the lawn. This stone block is called a splash block. Gutters should be checked every
spring and fall and cleaned when necessary. Gutters must be placed or installed
to ensure that water drainage is taken away from the foundation of the house. Soil
around the home should be graded in a manner that also drains the water away from
the foundation of the home.
Exterior Walls and Trim
Exterior walls are enclosure walls whose purpose is not only to make the building
weather tight, but to also allow the building to dry out. In most one- to three-story
buildings they also serve as bearing walls. These walls may be made of many different
materials (Figure
6.9).
Brick is often used to cover framed exterior walls. In this situation, the brick
is only one course thick and is called a brick veneer. It supports nothing but itself
and is kept from toppling by ties connected to the frame wall.
In frame construction, the base material of the exterior walls is called sheathing.
The sheathing material may be square-edge, shiplap, tongue-and-groove boards, or
plywood or oriented strand board (OSB). Sheathing, in addition to serving as a base
for the finished siding material, stiffens the frame to resist sway caused by wind.
It is for this reason that sheathing is applied diagonally on frame buildings. Its
role is to brace the walls effectively to keep them from racking.
Many types of sidings, shingles, and other exterior coverings are applied over the
sheathing. Vinyl siding; wood siding; brick, cedar, and other wood shingles or shakes;
asphalt; concrete; clapboard; common siding (called bevel siding); composition siding;
cement shingles; fiber cement (e.g., Hardiplank); and aluminum siding are commonly
used for exterior coverings. In older homes, asbestos-cement siding shingles can
still be found as an exterior application or underneath various types of aluminum
or vinyl siding.
Clapboard and common siding differ only in the length of the pieces. Composition
siding is made of felt, grit, and asphalt, which are often shaped to look like brick.
Asbestos and cement shingles, which were used until the early 1970s, are rigid and
produce a siding that is fire-resistant, but also a health hazard. Cedar wood shingles
and aluminum are manufactured with a backer board that gives insulation and fire-resistant
qualities. Vinyl siding is manufactured from polyvinyl chloride (PVC), a building
material that has replaced metal as the prime material for many industrial, commercial,
and consumer products. PVC has many years of performance as a construction material,
providing impact-resistance, rigidity, and strength. The use of vinyl siding is
not without controversy, because PVC is known to cause cancer in humans. Accidental
fires in vinyl-sided buildings are more dangerous because vinyl produces toxic vapors
when heated.
Putting It All Together
The next section shows a home being built by Habitat for Humanity. This small, one-family
home represents all of the processes that would also be used for a far more expensive
and elaborate dwelling. The homebuilding demonstrated by the following pictures
was by an industrial arts class to educate and train a new generation of construction
specialists and homebuilders.
The
foundation trench for a new home has
horizontal metal rods, also called reinforcement rods or rebar, to increase the
strength of the concrete. After the concrete hardens, a perforated pipe 4 to 6 inches
in diameter is placed beside it to collect water and allow it to drain away from
the foundation. This pipe is the footing drain, and the poured concrete beside it
is the footer. The footing drain is important in removing water from the base of
the home. It also serves the secondary purpose of moisture control in the home and
provides a venting route for radon gas. The holes dug near the legs of the workers
will be filled with concrete and form the footer that will hold up the porch of
the home.
To assist in preventing capillary action from wicking water from the foundation
to the wooden structure, a polyethylene sheet is placed over the footer before pouring
the concrete foundation, or building a cinderblock foundation.
The
concrete on top of the footer is leveled to establish a surface for the
foundation of the home. Once the footer has hardened, the perforated drainage pipe
will be laid on the outside of the poured foundation wall. The reinforcing rods
were positioned in the trench before pouring the concrete.
Concrete will be poured into this form on top of the footer to create the
foundation of the home. Again, reinforcing rods are added to ensure that the concrete
has both lateral strength, as well as the strength to support the home. Once the
concrete has hardened and becomes seasoned, the forms will be removed to reveal
the finished poured concrete foundation over the perforated drainage pipe. Not shown
is a newer technique of using insulating polystyrene forms and ties in a building
foundation.
Foundations are not always poured concrete, but are often cinderblock or
similar materials that are cemented in place to form the load-bearing wall. The
arrow shows the concrete chute delivering concrete into the form. Long poles are
pushed into the freshly poured concrete to remove air pockets that would weaken
the foundation. Care must be taken to ensure that the forms are appropriately supported
before pouring the concrete. Often tar, plastic, or other waterproof materials are
placed on the outside of the foundation to the ground level to further divert moisture
from the house to the footing drains.
Gravel fill is placed outside the finished poured concrete foundation. This
ensures that moisture does not stand around the foundation for any time. The moisture
is routed to the footing drain for fast dispersal.
A
termite shield is established on top of the concrete wall (foundation) just
below the sill of the home. The sill is typically made of pressure- and insecticide-treated
wood to ensure stability and long life.
A cinderblock foundation will be used to support the storage shed attached to the
house. Note the potential for inadvertent sabotage of the termite shield if a shield
is not installed on the top of the cinder block foundation.
The
OSB subfloor, the joist supporting the floor, and the metal bridging that
is used to keep the joist from twisting can be seen from the crawl space under the
home.
If the material used for the flooring or external sheathing of the home is made
of plywood or a composition that is not waterproof, the material must be protected
from rain to prevent deterioration and germination of mold spores. Some glues or
resins release toxic vapors for years if deterioration is allowed to begin.
The
flooring material of the first floor of the home is OSB applied to the subfloor
with both glue and wood screws. Where possible, the screws should extend into the
subfloor and the joist below the subfloor to prevent squeaking.
The
interior wall framing is composed of studs traditionally referred to as
2 x 4s. The horizontal member at the top of the studs is called a girt or a ribbon.
In this case the builders have used two 2 x 4s, placing one on top of the other.
Because the outside walls have used studs that are 2 x 6-inch boards, the girts
or ribbons on top of these are also double 2 x 6-inch boards.
The
exterior wall framing is composed of studs that are 2 x 6-inch boards. The
horizontal member extending from one exterior wall to the other is called a girder
and is a prime support for the second floor of the home. The larger studs in the
exterior wall are used both for greater strength and to provide greater energy efficiency
for the home.
The lintels above the windows and doors distribute the weight of the second floor
and roof across the studs that are located on each side of the openings in the frame.
The
joists above the first floor are connected to the central girder of the
home by steel brackets. These brackets provide a far more effective alternative
than does toenailing nails to hold the joists in place or to notching the girder
to hold them.
The
subroof or roof sheathing is applied from the bottom up with temporary traction
boards nailed to the subroof to allow safe installation of the material.
The subroof is placed on the rafters up to the ridge board of the roof. A waterproof
material will be added to the subroof before installing the final roofing material.
An
interior wall is installed to create second-floor rooms.
The subroof has been installed.
The exterior wood of the home has been covered with plastic sheathing or a housewrap
to protect it from moisture.
Flashing material, such as sheet metal, is installed at critical locations
to make sure that water does not enter the home where the joints and angles of a
roof meet:
- where the dormer roof meets the roof and the
walls of the dormer meet the roof,
- where windows penetrate the walls,
- where the vent stack penetrates the roof,
- where the porch roof meets the front wall,
- skylights, and
- eaves of the house.
A
safety scaffold is standing at the rear of the home, and the final roofing
material has been applied, in addition to the exterior vinyl siding.
The
front porch of the home is constructed of pressure-treated, insect-resistant
lumber. The use of such lumber should be carefully evaluated with respect to what
chemicals have been used and the potential for human exposure to the treated wood.
Composite wood products and plastic decking materials, collectively called Trex,
are available as an alternative to pressure-treated wood. A proper hand railing
and balusters will be installed.
References
- US Inspect. Glossary of
terms. Chantilly, VA: US Inspect; no date. Available from URL:
http://www.usinspect.com/Glossary/glossary.asp.
- Center for Disease Control.
Housing construction terminology. In: Basic housing inspection. Atlanta: US
Department of Health and Human Services; 1976.
- Building Science Corporation.
Read this before you design, build, or renovate. Westford, MA: Building Science
Corporation; 2004.
- Center for Disease Control.
Basic housing inspection. Atlanta: US Department of Health and Human Services;
1976.
- Wagner JD. Drying out
a wet basement. New York: This Old House Ventures, Inc.; no date. Available
from URL:
http://www.thisoldhouse.com/toh/knowhow/interiors/article
/0,16417,220912,00.html
- Friedman D. Inspecting
foundations for structural defects. Poughkeepsie, NY: Daniel Friedman; 2001.
Available from URL:
http://www.inspect-ny.com/structure/foundation.htm.
- Association of Bay Area
Governments. Foundations: section 5. Oakland, CA: Association of Bay Area Governments;
1998. Available from URL:
http://www.abag.ca.gov/bayarea/eqmaps/fixit/ch5.
- Crawford CB. CBD-148:
foundation measurements. Ottawa, Ontario, Canada: National Research Council;
1972. Available from URL:
http://irc.nrc-cnrc.gc.ca/cbd/cbd148e.html.
- Hamilton JJ. CBD-184:
foundations on swelling or shrinking subsoils. Ottawa, Ontario, Canada: National
Research Council; 1977. Available from URL:
http://irc.nrc-cnrc.gc.ca/pubs/cbd/cbd184_e.html.
- US Department of Housing
and Urban Development. Basements and crawl spaces. Washington, DC: US Department
of Housing and Urban Development; 2000. Available from URL:
http://www.hud.gov/offices/hsg/sfh/ref/sfhp1-25.cfm.
- Bateman BW. Light-gauge
steel verses conventional wood framing in residential construction. J
Construction Educ 1997; 2(2):99-108. Available from URL:
http://www.ascjournal.ascweb.org/.
- National Association
of Home Builders Research Center. Integrated steel/wood combination framing.
Upper Marlboro, MD: National Association of Home Builders; no date. Available
from URL:
http://www.toolbase.org/tertiaryT.asp?
DocumentID=4249&CategoryID=1142.
- Steel Wood Studs. Why use steel
wood studs? Reno, NV: Steel Wood Studs; 2001.
- Canadian Mortgage and
Housing Corporation. Understanding window terminology. Ottawa, Ontario, Canada:
Canadian Mortgage and Housing Corporation; no date. Available from URL:
http://www.cmhc-schl.gc.ca/en/burema/gesein/abhose/
abhose_061.cfm.
- US Consumer Product Safety
Commission. Safety commission publishes Final Rules for automatic garage door
openers. Washington, DC: US Consumer Product Safety Commission; 1992. Available
from URL:
http://www.cpsc.gov/cpscpub/
prerel/prhtml93/93024.html.
Additional Sources of Information
Carmody J, Christian J, Labs K, editors. Builder’s foundation handbook. Oak Ridge,
TN: Oak Ridge National Laboratory; 1991.
US Department of Housing and Urban Development. Basements and crawl spaces. Washington,
DC: US Department of Housing and Urban Development; 2000. Available from URL:
http://www.hud.gov/offices/hsg/sfh/ref/sfhp1-25.cfm.