We have a roughly 10×30 elevated wood deck off the pack of our house. The joists are all 2×6 16oc. The posts are 4×4 and are holding up a beam that the joists hang off of with joist hangers. I feel this deck is under built, though I will say it feels very solid for what it is.
I plan on doing the following:
- add a beam under the joists a foot or so in (to lessen the initial span).
- use 6×6 posts.
The big question: Do I need to replace the 2×6 joists and make them larger?
I'm finding mixed answers out there on the internet. Some span tables include 2×6 and claim about a 9'6" span when 16OC. Others simply say "don't use 2×6 joists.
If I do have to replace the joists, we're probably looking at a full tear down and starting from scratch. I can live with that, but if I can save the time, money, and extra waste going to the dump by keeping the 2x6s, I'd be certainly for it.
Best Answer
According to the table in the 2012 IRC code a exterior deck needs to handle a 60lb per sq ft (40 lb live + 20lb dead load). Most treated lumber that I am aware of is #2 southern yellow pine, using that criteria on the table in the code book, your joists can carry a 10'-9" span.
The biggest failure in deck construction has not been the posts or the joists, but the connection to the house. I believe code now requires through bolts into the band joist, or the joist of the house, or posts at the house is cool too.
The length of the post will dictate whether they need to be 4X4 or 4X6. Its a deflection (bowing) thing. IMO 4X4 for a 10' span is not overloading the post, a 16' span may...