How to support a free standing 24 x 21 foot roof over existing concrete deck.?
Question:We want to span the 21 foot width without supports in the middle. We've placed (8) 6x6 posts in existing concrete using (4) 3/8 1.5" concrete screws in metal post holders. We can't use longer 5/8 inch bolts, we're hitting rebar in the concrete.
4 posts are 11' tall and 4 are 6' tall (12/3 pitch) on the 24' sides (8' apart). We pre-built two 28' beams with 1/2 plywood in between 2x10s. We plan on placing these on top of the 2 sets of posts with hangers.
We then pre-built four 24' beams with 1/2 plywood in between 2x12s. We plan to span the 21' opening every 8' directly on the 2x10 beams. We will then use 2x12s every 2' in between the beams. I was told by a contractor that using 2x12s to span 21' would sag without the help of the "sandwich" beams every 8'. We are going to put 2x4s across the joists & beams with a metal roof.
Any flaws in my plans? I'm worried about the weight of the roof, use of small screws in the post holders and the 21' span. Thank you!!
Answers:
This is going to fall down in the first good wind. This has so many flaws that a few suggestions would not be enough.
Your beam and rafter plans seem sound.
The only potential issue I see is the method of anchoring your posts to the concrete. What will keep a strong wind from pushing this roof over? Your posts need to be anchored more securely.
Must find a way to have better anchored support posts. These posts need to be much deeper than the rebar. And the roof sounds too heavy for that much middle space.
I didn't check but maybe you will find additional help in
www.hgtv.com AND check with another contractor.
If you don't, I truly believe you will be sorry & have a big redo.
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