Hi
I've been asked to build a 15' x 12' wooden deck to hold a hot tub. Most of the joists can rest on a small retaining wall, a concrete slab and a wall plate fixed to the garage wall.
The tub holds 1300 + litres of water & up to 6 adults, so adding the (as yet unknown) weight of the tub itself I could be looking at 2 tonnes here.
Would I increase the strength much by spacing the joists at 12" rather than
16" or would extra noggins be a better bet?Cost isn't the major issue, I just want to make sure it's strong enough.