well constructed sub frame is the key to any successful deck build. A well constructed sub frame is the key to any successful deck build.
Whenever possible I use a minimum 6” x 2” treated timber to construct the framework. The use of thinner 4” x 2” timber is not advised and the result is an inferior standard framework on which to lay the deck boards.
The main advantages of specifying 6” x 2” timber are:-
It is less likely to warp or bend giving a “truer” surface onto which to attach your decking boards.
Around the perimeter of the deck it provides a greater depth of fixing for any handrail posts. The greater fixing depth allows a more robust and hence safer attachment of handrails to these posts.
Apart from the use of 6” x 2” timbers three other items require mention;-
I only use a propriety brand of decking screws to assemble my decking framework, the joists are screwed together not nailed As discussed later I do not use nails for fixing anywhere on my decks
Apart from the main joists I also install cross bracing at regular intervals this has the effect of stiffening up the supporting framework resulting in a stronger deck.
Finally, and perhaps more importantly I always seal the cut end of any joists. I use Thompson’s End Seal Preserver but there are a number of other proprietary products on the market which would do equally as well. The use of end seal has the effect of reinstating the treated coating applied to the timber joists and thus helps to extend the life of the joists.