We've got a 13.5' square deck on a concrete slab and are going to put a SD Optima on it. I was tidying up the deck boards when I realised the joists just aren't going to cut it.
The joists are at 20" centres. They're 1x4" (laid flat) and are supported by 4x4 feet at 20" centres. The good news is that the joists are only 1" off the ground, so those feet won't be bowing! Oh, and the slab is sloping on all sides towards a drain in the middle, so it'll be really difficult to use concrete feet.
I'm guessing that all this framing has to come out and be replaced by something more solid. I was planning to use 2x4" joists (laid flat) supported by ~1" high 4x4" 'feet' every 16", but everything I'm reading about decks for spas indicates those joists need to be 2x8" (laid tall) and that the joist centres need to be 16".
Does that sound right, or would I be okay with smaller timbers (2x4" laid flat or 4x4"). And is the 16" 'feet' spacing right?
