Information for Builders
Builders and contractors have some pretty big shoes to fill. They are the critical link between the designers, the local code official, and the owners or residents of the building. A builder's reputation is usually based on the quality of the finished product, so the best builders rely on AWPA to write the standards for the treated wood products they use in their structures.
Why should I require wood treated to AWPA Standards?
Besides the fact that most architects and engineers specify AWPA Standards for treated wood, AWPA Standards are the only wood treatment standards listed directly in the IBC and IRC. AWPA has over 110 years of history in developing treated wood standards. Our standards are developed in an open, consensus-based, ANSI accredited process to ensure stringent review of performance data while providing due process for all participants. Most of the world's experts in wood protection actively serve on our Technical Committees - a level of expertise unmatched elsewhere.
The building inspector says I need to use a preservative to coat the cut ends of treated wood. What should I use?
The inspector is probably referring to AWPA Standard M4, which requires the use of borates for interior uses, and copper naphthenate or oxine copper for primarily exterior uses. For borates, commercial products such as "Bora-Care" may be used, but saturated solutions of borax and/or boric acid in hot water may also be used. The only commercially available oxine copper product we're aware of is called "Outlast Q8 Log Oil", and it is normally found at log home supply companies. And finally, copper naphthenate is sometimes found at paint, hardware, and building supply stores, but it can be difficult to locate. A 2% copper solution may be purchased online from Poles, Inc. under the trade name "Tenino". It is always a good idea to coat cut or drilled areas of pressure treated wood with a topical preservative to re-establish an envelope of preservative protection.
Can I use a brush-applied or sprayed preservative instead of pressure treated wood?
A brush on or spray on preservative is just a surface treatment. When wood is put into service it is immediately exposed to the rigors of water, decay fungi colonization, termites and UV and visible violet light degradation. The wood will at first check (cracks along the grain) at a microscopic level, and later into increasingly wider checks. Although the first openings are microscopic they are more than adequate to allow these wood destroying fungi past the paint on surface protection to the unprotected wood just below the surface where once established will ultimately make the wood unfit for the purpose it was installed. If such a “surface” treatment existed it would be marketed as well as acknowledged by the Forest Products Laboratory or AWPA. Only pressure treated wood penetrates below the surface for more thorough protection of the wood.
Is "mold resistant" treated wood the same as pressure treated wood?
Mold resistant wood is specifically designed to do what it says…resist mold growth. It is not a replacement for pressure treated wood. Mold, although unsightly and a potential source of airborne toxins is not in itself a very great threat to wood structure and the soundness of wood members. Mold resistant wood should not be used outdoors or in areas expected to be in contact with soil or masonry such as sill plate. Pressure treated wood has various “Use Categories” that can be viewed in other parts of this website that identify the proper use of matching an application with the right level of preservative protection.
Can wood be preservative treated and fire retardant treated at the same time?
Under AWPA Standards, preservative treatment and fire retardant treatment are two different technologies. Preservatives are expected to protect the wood from decay fungi and termites every day over a long period of time. Fire retardants are expected to remain in the wood and protect it from a one-time event. Some preservatives do impart a degree of fire retardancy, and some fire retardants can act as preservatives to some extent. At this time, there is only one AWPA standardized product which may be used both as a fire retardant and wood preservative, and it is only listed for interior uses. Apart from this, fire retardant treated wood should not be used where preservative treatment is required, nor should preservative treated wood be used when fire retardant treated wood is required.
What kind of fasteners and connectors should I use in pressure treated wood?
AWPA's test methodologies are used to determine relative corrosion rates, and cannot be used to estimate corrosion of fasteners and connectors in the field. For this reason, we suggest using fasteners that meet the requirements of the major model building codes, which specifies hot dip galvanized steel, stainless steel, silicon bronze, or copper fasteners. The model codes also allow for the use of mild steel fasteners for wood treated with inorganic boron (SBX) in dry environments. There are literally hundreds of fastener coatings available, so it is important to follow the fastener manufacturers recommendations regarding compatibility of their fasteners with pressure treated wood.