I am planning a deck with dimensions of 14' x 20', where that is 14' out from the house, and 20' along the house wall. This will be an elevated deck with 2' of that outward span cantilevered. The plan calls for 16" OC joists and blocking at the halfway point of the span.
My question is about creating the stiffest feeling for the deck. Basically, is it better to do more blocking or 12" OC joists? I don't want that "springy" feeling at all. Nice and solid.
Best Answer
Deeper Joists
I assume that you've spec'd at least 2x10s for a 14' span. Bump to 2x12s on the same 16" centers for a noticeable improvement in stiffness.
More Joists
Taller joists offer a greater stiffness gain, but if height is a concern you could use more joists (say at 12" centers). The main drawbacks are cost and appearance, as you'll use more materials and have more screw stripes across your deck.
Thicker Decking
By tying the joists together more robustly you split load between joists better. 2x6 lumber is much stiffer than 5/4. The main drawbacks (aside from cost) are that you'll need longer screws and the appearance won't be as polished (edges are typically sharper and not as uniform).
More Joist Blocking
More blocking will have a similar effect to using thicker decking, spreading load among more joists, with none of the appearance compromise. Install two or three runs. It's more work, and you do need to fit them well. You'll use many more screws and quite a bit more lumber