I am designing a deck that will off the back of a home on the first floor. The ground drops away however, so it will be the equivallent of a 2nd story deck. The length against the building is 16′, out 12′. The outer two corners are cut 45 degrees at 4′ back from the corners. The house owners want the deck cantilievered on the outer side. They also want a 16’/10’concrete pad under the deck as free of posts as possible to maximize space.
The question I have is what is the best way to go about it. I was thinking about placing the posts and footings on the outer edge of the pad (10′ out, 10′ apart), and then building a 4x beam out of 2×12″s to to carry the 2′ cantilever. Joists would be 2×8″s, or 2×10″s.
Is my thinking on target? (Sorry this is so exhaustive)
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I'd run two 4x8x16 girders with three posts on each for a total of six posts. The joists would be 2x4x8's on 24" centers. I usually overbuild decks to some extent because it saves a lot of headaches trying to fix squeaky boards. You might mention to the home owner that minimizing posts can lead to unwanted flex as the deck ages. That flex can cause squeaks and poped nails or cracked boards if screwed.
I think no-ones framing ideas are moving the opposite dirtection from solving your design situation.
I won't do the detail work for you but I think you've got the right concept with this critique, Your beam is slightly undersized for all that cantileverage and I try to have it solid or engineered. The built up will trap water between pieces and encourage rot. PT should solve a lot of that tho' and all deck work should be framed with PT
As you describe it, the beam would not support the perimeter so as I was thinking about it I scetched this up as a possible alternative..
With all the discussion about decks falling off houses, wouldn't it be preferable to have two more columns at the house ends of the beams? Even if that end were fastened to the house for rigidity, the additional posts would carry most (all?) of the load.
sure, but like I said, I'm not doing his detail work for him. Where are the windows and doors leading out onto the slab underneath? Could be doggoned inconvenient to have a post right there when you try to open the storm door.Excellence is its own reward!