General FAQ's
Why does wood need to be protected with preservatives?
How long will treated wood last?
How much weight does treatment add to the weight of wood?
Why is treated wood green?
Why can’t I burn my wood scraps?
What should I use to apply to the cut ends of my boards?
Can I use treated wood inside?
Where can I learn more about the safety and environmental aspects of CCA treated wood?
Installation & Maintenance FAQ's
What type nails or screws do you recommend?
How long do I need to wait before I paint, stain, etc. my deck?
What do you recommend I use to paint, stain, etc. my deck?
Someone told me not to use concrete to set my posts - that it would void the warranty.
How do I remove the grade stamp from my deck?
What do you recommend I use to clean my deck?
Wood Preservative FAQ's
What preservatives are used to treat pressure-treated wood?
What is CCA?
What is ACQ?
What treatment and retention level should I use for above-ground applications?
What treatment and retention level should I use for ground-contact applications?
What treatment and retention level should I use for freshwater contact?
Why does wood need to be protected with preservatives?
Wood is an environmentally sound, economical building material that can be used either indoors or outdoors for a wide variety of structural and decorative applications. Unfortunately, untreated lumber cut from most commercially harvested tree species is subject to attack by insects or to decay caused by fungi and bacteria. The decay or insect hazard is greatest in exposures where the wood is subjected to moisture. Wood in outdoor exposures, either in ground-contact or in above-ground applications, is susceptible to attack. The potential for wood deterioration is greatest in hot and humid climates, which allow insects, fungi and bacteria to thrive. Destruction of untreated wood in aquatic environments can be caused by a variety of marine organisms. Wood should be treated with a preservative system to control the destructive activities of these organisms and ensure long-term structural soundness and serviceability.
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How long will treated wood last?
The length of time that a piece of treated wood lasts will depend on how it is being used and where. For best results, it is important that you use a treatment level (retention) appropriate to the end use. Thus, for an above-ground application 0.25 pcf CCA or ACQ is suitable. For ground-contact applications, 0.40 pcf CCA or ACQ is appropriate.
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How much weight does treatment add to the weight of wood?
Most of the weight added to treated wood comes from water used to solubilize the preservative components. A freshly treated piece of lumber may contain as much as 4.5 gallons of water per cubic foot or about 38 lbs. per cubic foot. As the wood dries and the water evaporates, only the preservative will remain. Lumber tagged for above-ground use should contain 0.25 pounds preservative per cubic foot and, for ground contact, 0.40 pounds per cubic foot.
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Why is treated wood green?
The green color you see on treated wood is caused by chemical reactions that take place between the preservative components and the wood as it dries and reacts to sun's ultraviolet rays. Over time, the green color will fade. SupaTimber CCA treated lumber eventually weathers to gray while Preserve treated lumber changes to a brown color and finally gray over an extended period of time.
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Why can't I burn my wood scraps?
When treated wood is burned, the chemical components of the preservative are concentrated and can be released into the ash and in particulates in the smoke. Some of these components can be harmful to the environment. Federal and state regulations mandate that treated wood be burned in an approved commercial or industrial permitted incinerator facility. See the Safe Handling section of this site for more information on handling and disposing of treated wood products.
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What should I use to apply to the cut ends of my boards?
For cut ends of treated lumber, we recommend you use a brush-on copper naphthenate formulation available from home centers, lumber dealers and hardware stores.
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Can I use treated wood inside?
Pressure-treated wood may be used inside as long as all sawdust and construction debris are cleaned up and properly disposed of. SupaTimber CCA or Preserve pressure-treated wood does not emit vapors or fumes. You do not want to use treated wood for countertops or where it may become a component of food. In fact, the Food and Drug Administration does not recommend using any wood for kitchen countertops or food-cutting boards because knife cuts may allow food particles to become entrapped, creating an unsanitary environment.
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Where can I learn more about the safety and environmental aspects of CCA treated wood?
As an EPA requirement, CCA treated wood has a Consumer Information Sheet (PDF 32 KB) that explains more about CCA treated wood.
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What type nails or screws do you recommend?
Hot dipped galvanized and stainless steel fasteners are suitable for use with preservative treated wood. There are also a number of new-coated fastener systems available. A bulletin detailing the use of fasteners with ACQ treated wood is available here: Fastener Bulletin PDF (128KB)
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How long do I need to wait before I paint, stain, etc. my deck?
Pressure treatment with waterborne preservatives leaves moisture in the wood that can affect the penetration and drying of stains and paint. For optimal performance of a paint and stain coating, it is important to ensure the treated wood is dry and clean prior to the application. How long treated lumber will take to dry will depend on the time of year and the weather conditions. If possible, test for wood dryness on a scrap piece to see if the finish applies properly.
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What do you recommend I use to paint, stain, etc. my deck?
We recommend you use a good quality oil-based product. Transparent or semi-transparent products work best. Solid products just lie on the wood and do not move with it. This results in peeling. We cannot recommend brand name products, however Consumer Reports published their findings in the June 1999 issue.
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Someone told me not to use concrete to set my posts - that it would void the warranty.
Setting the posts in concrete does not affect the warranty in any way. The question of whether to use concrete or not has been around for quite a while. Tests have been conducted to determine whether concrete causes the wood to fail and the results were inconclusive. In New Zealand, the government requires that the poles holding up houses be set in concrete. They've not had any problems.
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How do I remove the grade stamp from my deck?
A light sanding will lighten it somewhat, but you will really have to wait for it to fade with time.
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What do you recommend I use to clean my deck?
There are many products in the marketplace today that work very well. Or, you can use soap and water with a brush. To remove mildew, use a diluted solution of bleach (3 parts water to 1 part bleach). Be very careful, as this will lighten the wood.
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What preservatives are used to treat pressure-treated wood?
A wide range. The American Wood-Preservers' Association standards provide a complete list of accepted standard formulations in the US. Chromated Copper Arsenate (CCA), Alkaline Copper Quat (ACQ), Pentachlorophenol, Creosote and Ammoniacal Copper Zinc Arsenate (ACZA) are the most widely used systems.
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What is CCA?
CCA stands for Chromated Copper Arsenate, a wood preservative formulation containing copper, chromium and arsenic. The copper acts as the main fungicide and also provides some protection against termites. Arsenic provides protection against termites and copper-tolerant decay fungi. Chromium helps to bond and "fix" the chemical components to the wood.
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What is ACQ?
ACQ stands for Alkaline Copper Quat, a wood preservative formulation that contains copper and quaternary ammonium compound (quat) as active ingredients. Copper is a very cost-effective fungicide protecting against decay. It also provides some protection against termite attack. The Quat provides protection against termites and certain types of fungi that are tolerant of copper.
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What treatment and retention level should I use for above-ground applications?
Recommended retention for ACQ and CCA preservative treatments is 0.25 pcf.
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What treatment and retention level should I use for ground-contact applications?
Recommended retention for ACQ and CCA preservative treatments is 0.40 pcf.
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What treatment and retention level should I use for freshwater contact?
The same level of treatment as recommended for ground contact should be used for freshwater applications. The recommended retention for ACQ and CCA preservative treatments for this application is 0.40 pcf.
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