Friendly Forest Products

Wooden structures are really architectural elements

Wooden structures are really architectural elements, it is important that they relate strongly to nearby architecture, in most cases, the residence. It has always been a mystery to me why homeowners who demand the finest of materials and detailing on the interior of their homes, settle for the crudest of materials and workmanship on the exterior. Where the typical deck is concerned, if it has any style or detailing at all, it is often inappropriate or irrelevant to the structure to which it is attached. A great opportunity exists for the designer to identify the style of the architecture and then make a conscious decision to either design in harmony or contrast with that style.

Material selection

Regardless of the specific application, wood selected for exterior use must be resistant to decay and insect damage. Structures which will be wet for prolonged periods of time are particularly susceptible to the decaying process; therefore appropriate wood selection, construction techniques, and long-term maintenance are important considerations for the designer. Heart redwood, Western red cedar, Spanish Cedar, Teak, Ipe, and a number of other tropical woods are naturally rot and insect resistant.

With chemical treatment, Southern yellow pine is also resistant. Pressure-treated Southern yellow pine is perhaps the most widely used exterior building material in our region. This wood is much stronger than redwood or Western cedar, has greater nail and bolt holding power and a longer life expectancy. Its decay and termite resistance comes from its treatment with CCA (chromate, copper and arsenate) preservatives. According to the EPA, although these chemicals are toxic, once fixed in the wood only small amounts will leach over time. Incidental contact with skin and food are considered safe by the EPA. CCA-treated wood often arrives at the jobsite retaining moisture from the water-based treatment. As the wood dries twisting, cracking, checking and warping often occurs. Pressure treatment does not impart waterproofing, and when pressure- treated wood is left unprotected it will absorb water and inevitably exhibit the instability associated with the resulting expansion and contraction.

Among tropical woods, Ipe (Pau Lope) is the most accessible in terms of availability and price. Naturally resistant to insects and decay, this Brazilian import is remarkably dense and can be difficult to work. Ipe is dimensionally stable and has structural capabilities well beyond that of Southern yellow pine. Since it is nearly impervious to water, it requires no preservatives. Its life span is reported to be 50 years -- a good choice for a client who takes the long view.