Pressure-Treated Wood

• The most common type of wood decking material is pressure-treated wood, which is typically pine impregnated with preservatives such as alkaline copper quaternary and copper azole. The preservatives protect the material from termite and rot, especially when it is close to the ground. Pressure-treated wood is available in several grades, from smooth, premium, knot-free versions suitable for railings and platforms to lower, imperfect grades for hidden structures or a more rustic appearance. Though impervious to organic damage, the wood can suffer from moisture damage that causes warping, cracking and general deterioration. It requires an application of a water repellent product every year to extend its life.
  
  

Cedar

• Western red cedar is a soft wood that is lightweight and naturally resistant to moisture, decay and insects. Its colors range from amber to light brown, but it weathers to gray and then dark brown if untreated. As a decking material, it contains no artificial chemicals or petroleum-based products, and it has almost no resins, making it simple to stain and paint. It also has naturally occurring chemicals that give it a characteristic aroma. Though cedar can be left untreated, preservative treatment and sealing is necessary for to achieve its greatest durability.
  
  

Redwood

• Redwood is a soft wood that varies from light red to dark reddish-brown, and it weathers to black and then silver-gray if untreated. Its highest clear heart grade is particularly resistant to decay and insects, and so it doesn't need chemical or preservative treatment. A protective finish that inhibits ultraviolet damage and repels water, however, helps redwood last up to 30 years. It’s less likely than other wood to warp, shrink or split, but it can be brittle, requiring nail, screw and bolt holes to be pre-drilled. Though redwood was once the most common option for decking, it is expensive due to its limited supply. It is available primarily on the West Coast and may be difficult to find elsewhere.
  
  

Others

• Mahogany encompasses many species, though the two most common for decking are from Honduras and the Philippines. The colors that are most resistant to decay are red and brown. Ipe, from South America, is highly resistant to splintering, chipping and warping, but its strength makes it difficult to cut, which increases the expense to install ipe.
  Cypress resists rot and insect damage. It grows in wet, swampy areas on the East Coast and is very water-tight. No treatment or sealing is needed for cypress deck boards to survive up to 100 years.