For several decades, pressure treated wood (PT) has been the most popular material for the construction of decks in Toronto and even in all of North America. About 80% of decks are built from this particular material. The secret of the popularity is simple: it's a combination of the low price and high quality of the material.
PT wood used to be manufactured in a light green shade that, being exposed to the sunlight, eventually acquired a light yellow colour. In the last few years, most manufacturers have switched to a new wood treatment technology and changed the colour to a light brown. With time, the brown becomes lighter and then acquires a gray colour.
For more than 65 years chromated copper arsenate (CCA), carcinogenic when in high concentrations, was used in the production of PT wood. Today, less toxic substances are used in the production of PT wood: alkaline copper quaternary (ACQ), copper azole, or carbon-based nonmetallic preservatives. However, this material is not recommended for burning or to use for a BBQ.
Properties of PT wood
Like any other material, PT wood has a number of advantages as well as some disadvantages.
The main positive feature of PT wood is its durability. A deck built from PT wood is able to withstand more wear and tear than other materials. PT boards are much more resistant to scratches and dents than cedar or composite.
A deck built from PT wood is very long-lasting. With proper maintenance, it will last for 30-40 years without a problem.
Another advantage of pressure treated wood is its resistance to insect damage. The chemicals used in its processing make PT wood absolutely inedible for insects. As PT wood is rot resistant, posts made of this material have a durability class that allows their use below-ground. By the way, regardless of the deck material, the frame is usually made of pressure treated wood.
The main drawback of PT wood is it's not being environmentally friendly. It can be an irritant for some people, so you should take the necessary precautions when handling it.
Due to the fact that PT wood is made of pine, and green timber is full of water (this is part of the technological process), it is prone to warping, splitting, cracking, and splintering.
In the construction of pressure treated decks, we only use dip-galvanized nails, brackets, bolts, screws, and other hardware. To attach the boards to the frame, we only use dip-galvanized nails (coated with zinc) or, as a higher-priced option, green powder coated screws.
The most attractive aspect of PT wood is its cost. This material is the most affordable of all alternatives in the deck construction market. If your project is a very large deck, then it's likely you will choose pressure treated wood, because the difference in price with composite or cedar will be very noticeable.