What Size of Decking Should You Use?

1x6 & 5/4x6
vs.
1x4 & 5/4x4

Why do customers prefer 6” decking widths over 4” widths? Ease of installation would seem to be the only explanation. While that may be true, there are several reasons why 4” decking should always be preferred over 6” decking.

FACT: Wood deck boards shrink and expand as they lose and take on moisture.

FACT: 6” boards are 50% wider than 4” boards; 5-1/2” vs. 3-1/2”.

In close to ground applications, the deck boards will absorb moisture off the ground, and they will dry out from the top. This creates cupping, and 4” boards will always perform better than 6” boards in this application.

With 4” deck boards fastened with 2 screws per joist, the screws are spaced approximately 1-1/2” closer together than with 6” boards. The movement when 4” deck boards expand and shrink will put less side to side stress on the deck boards, and therefore 4” decking is less likely to break fasteners.

While it is true that more fasteners are required to install 4” boards than 6” boards, 4” boards have the advantage of superior long term performance.

4” width deck boards are also easier to install in terms of alignment. They are more flexible and it is easier to achieve the ideal spacing between boards. More importantly, because they move less, 4” boards are less likely to close up during wet weather and they are less likely to show large gaps during dry weather.