Build this Cozy Cabin

In this cabin design, you need one pier at each corner of the cabin, one in the middle of each long side, three piers spaced evenly on the front of the porch and one in the middle of the rear wall. In light soil, it’s reasonable to dig the 10 holes you need for 8- to 12-inch-diameter pier forms using a long-handled shovel. Otherwise, call in a neighbor or contractor with a tractor-mounted auger. You can use 8-inch concrete piers, but the larger size is more forgiving if you don’t get the alignment just right.

The best way to mark your foundation outline is with 12-inch spikes pushed into the earth and connected with nylon string. (See “Choose a Rock-solid Start,” below, for layout tips.) Regardless of the foundation design you choose, the main construction challenge is the same: leveling the top of the foundation pads or piers. A laser level is easy to use and even allows a person working alone to level a foundation successfully. You don’t need to buy a laser level for this project, but it’s definitely worth borrowing if one is available from a friend or neighbor.

When setting concrete pier forms in the ground, dig the holes large enough to allow room for side-to-side adjustment. The outside edges of the pier forms should extend a bit beyond the outer dimensions of your building. As inexpensive insurance against frost jacking of foundation piers (when the piers are pulled toward the surface by seasonal freezing, even though they extend below the frost line), wrap the outside of each pier tube with black polyethylene plastic before setting them into the holes and packing soil around them. While the concrete is wet, vertically embed five-eighths-inch L-shaped threaded metal rod anchors, extending at least 7 inches above the concrete, short end down. Later on, these will hold down the base of the floor frame.

Building the Floor Frame

There are many ways to frame a cabin floor, but I favor the timber-rim approach for a couple of reasons. “Timber rim” refers to a load-bearing frame of timbers that defines the perimeter of the floor area. It’s better than a continuous foundation wall because it eliminates the need for lots of block work or a poured foundation, and it offers great stability. For this project, it provides continuous support for a building that’s held up at only 10 points around its perimeter. Another plus is that timber-rim construction is durable and simple for first-time cabin builders.

Start by gathering rot-resistant 6-by-6 timbers for the outer rim. Timbers for the ends of the cabin and porch should be long enough to do the job in one piece. If you need to splice two timbers together for the 20-foot cabin sides, that’s fine. Just locate the splices directly on top of your concrete pads or piers. (It is possible to get away with thinner pieces of wood here, but that would require adding more piers — an option that’s probably less attractive than dealing with thicker timbers.) Be sure to make half-lap corner joints to connect the rim timbers.