Treatment for Natural Wood Siding

Use a pigmented, wood treatment to add protection and color.

Natural wood has been a popular option for siding for centuries. With proper treatment it remains attractive throughout its lifespan. There are several wood treatments available depending on what protections you want from a product. Some treatments simply repel water while others protect against other destructive elements and serve as a finish. By applying and maintaining the wood treatment, your siding will resist decay for many years.

Types

A penetrating type of treatment gives the best performance on many natural wood sidings. These treatments are available in water repellents, colorless, water-repellent preservatives and solvent- borne, semi-transparent stains which have coloring pigments that increase the durability of the protective finish. The water-repellent preservatives and solvent-borne stains contain water repellents, mildewcides and fungicides to protect the wood siding from decay.

Function

Wood treatments protect from decay caused by weather, insects and other elements. Water-repellent preservatives also protect against mildew and fungus and some even contain ultraviolet light blockers to protect wood from damaging sunlight. Solvent-borne, semi-transparent stains penetrate into the wood without forming a film which can crack or blister. They contain preservatives and moderate coloring pigments, providing a finish which allows wood grain to show through. Plain water repellents repel moisture and can be used as a stabilizing treatment prior to applying a primer and paint finish, but do not offer other decay protections and provide no finish.

Characteristics

Water repellent treatments contain a small amount of wax to repel moisture which reduces the shrinking and swelling of the wood. Those with preservatives usually contain fungicides, a resin or drying oil and a solvent. They do not contain coloring pigments like solvent-borne, semi-transparent stains. The penetrating stain treatments are often oil-based, containing the same protective elements as the preservatives along with a semi-transparent color.

Application

An effective way to apply water-repellent preservatives to natural wood siding is by dipping the boards entirely into the treatment solution. Since this can be tedious and time-consuming, applying the treatment with a brush after the siding has been installed is a common, alternative method. Applying the treatment to the wood until it will no longer accept it increases the strength and durability of the siding. It's important to apply the solution liberally to all the joints, edges and ends for the best protection.

References

• USDA Forest Service; Wood Siding – Installing, Finishing, Maintaining; W. C. Feist , et al.
• University of Maryland Extension: Selecting Preservative Treated Wood
• Western Red Cedar Lumber Association; Finishing Western Red Cedar Decks; William C. Feist