Deck support questions...

[Scarpozzi]

Has anyone here used 4x4's as beams to support a deck? I'm going to build a 16' X 20' deck out of treated 2x8's and am going to run 16' + <4' boards as my joists (my supplier doesn't stock 20' dimensional treated, so I'm breaking it up)

My plan is to span 16' with the 4x4 beam, but will have piers every 5-6' directly under the beams... I'm only looking at 4x4's as beams because the deck is only a foot or so off the ground...

 

[mztykal]

Too skinny...4x6's at least...

 

[Scarpozzi]

Too skinny...4x6's at least...

If I have the space for it, definitely... I'm just talking worst-case. I don't really want to lower the grade if I can help it.

 

[Humpy]

Using joist hangers you wouldn't necessarily need a beam at all.

 

[Scarpozzi]

Using joist hangers you wouldn't necessarily need a beam at all.

Joist hangers will be used. I'll need posts to support the structure and have to break up the spans because I'm not using 2x12 lumber.

When I say beam, I was initially going to support the solid spans underneath by running a couple of support beams made out of 2x8's to avoid cutting. After going back and measuring, I'm going to be stuck breaking the spans down into 6' sections and by the time I double up on 2x8's with the 4x4 posts, that will work out...but ultimately, I'll need to do many more cuts and need 50% more hangers....

 

[Greenman]

I'm having trouble visualizing the framing you're describing, a line drawing would be helpful.
For the hangers and hardware, be sure it's ICQ rated or it will rust out very rapidly.

 

[Scarpozzi]

I'm having trouble visualizing the framing you're describing, a line drawing would be helpful.
For the hangers and hardware, be sure it's ICQ rated or it will rust out very rapidly.

I ended up using 2X8s. I connected a ledger to the house with tapcons on the block, then used that as a nailer for the first cross joist. The ledger will serve as a mounting point for j-channel for the bottom row of vinyl siding along the deck floor. Prior to that, I had a metal starter row 5" lower.

I basically made a few 10X16 boxes (spanning 115") with posts between them for support in the middle...then drove galvanized carriage bolts through them. On the outside edge of the deck, I used 4x4 posts and bolts as well.

I'm using metal hangers and galvanized hanger nails (1.5") and 12d galvanized 3 1/4" nails where I can for extra support. So far the deck has a little bit of bounce to it, but it will be better once I get the decking boards on it. I figure if I'm not happy after decking 25% of the top surface, I can always try sliding a few posts on their side underneath the center of the deck sections midway and block it to break the span...without too much extra work.... I just didn't want to do more permanent posts or break the spans up to require more cuts and materials. I should be able to finish this 16'X20' composite deck project under $2200 by the time I'm finished.

 

[Scarpozzi]

I finally got most of the work done and called the city office to get them to inspect it. They said, "Ok...we'll come out for your footer inspection..." I wasn't sure how to take that because I sort of have more than just footers in the ground at this point:

I suppose since the inspector wrote "PASS" on the inspection, I'm good to start adding my decking?