Pressure Treated Decking
Pressure Treated Decking is typically a Hem-Fir that has been immersed in a liquid preservative and placed in a pressure chamber. The chamber will force the solution deep into the wood fibres giving a greater degree of protection. For lumber that will be touching the ground there are incisor marks on the surface which helps the solution seep further into the wood. For pressure treated decking boards the wood is not touching the ground so the incisor marks are not used. The name of the chemical used in this process is called alkaline copper quaternary (ACQ). The copper is toxic to various insects and fungi that would damage the wood. A few important details must be followed when installing pressure treated decking. For starters the type of fasteners is a very critical detail, the chemicals used are very corrosive and all of the fasteners must be ACQ approved. They are either a ceramic coated screw or a stainless steel screw. Another important aspect is treating the cut ends with a high quality wood preservative (preferably a end-cut solution). Even though the pressure treatment is adsorbed into the wood fibres it doesn't typically reach the core. So if this step is missed the pressure treated decking can rot from the center out. There is a special type of pressure treated decking that has the chemicals adsorbed all the way into the core (more on this later).
"Pressure Treated Decking" Options
After the size and framing layout have been determined there a couple of more decisions that need to be made before the pressure treated decking can be installed. First off the decking layout should be decided upon. There are three common styles that are used, Diagonal Decking, Chevron Decking and Picture Framing. Another option is that we can install Diamond inlays to make the pressure treated decking stand out.
After that has been decided one of the last things to determine is the type of pressure treated decking you wish to use. There are three main styles 5/4 x 4",
5/4"x 6" and 5/4" x 6" FP Pressure Treated.
5/4"x 4" and 6" Pressure Treated Decking
This style of pressure treated decking comes in 3-1/2" and 5-1/2" widths. The edges are slightly rounded this adds a nice look to the deck. When ordering the material it is best if you can get the wood in full lengths to avoid having any joints in the field. Some decks are so wide that you can't avoid having joints in the decking. When this is the case the joist at the joints should be doubled or solid blocking installed to offer more support to the joints.
FP Pressure Treated Decking
This product has rounded edges and grooves on the top surface. Not only does this add to the over all look of the finished pressure treated decking, but the grooves add a lot of traction to the deck making it very slip resistant. One of the largest benefits of this product is that the FP stands for "full penetrations". So the ACQ is absorbed by the wood all the way to the core. So there is no need to treat the cut-ends with preservative.