deck over raised concrete patio
#1
06-18-13, 06:01 AM
Join Date: Sep 2008
Location: ny
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deck over raised concrete patio
i have an existing raised concrete slab patio that i am considering putting some decking over. (stamped overlay prices were significantly more than i'm willing to spend on this)
i was planning on using PT 2x4's laying on the face as sleepers and then installing PT 5/4 deck boards over that. ideally i would like a bit more room for ventilation under the decking, but i'm somewhat limited here.
one of my biggest concerns is with how to fasten the railing posts. i was thinking of using PT 2x8's as skirting for the edge of the 4.5" thick slab. i'll use vertical 2x4's as furring strips on the sides of the slab to allow for drainage, but those would just be fastened with tapcons. is that too much load (skirting, 4x4 posts + railing + live load) for this type of connection?
any other tips/advice?
thanks!
i was planning on using PT 2x4's laying on the face as sleepers and then installing PT 5/4 deck boards over that. ideally i would like a bit more room for ventilation under the decking, but i'm somewhat limited here.
one of my biggest concerns is with how to fasten the railing posts. i was thinking of using PT 2x8's as skirting for the edge of the 4.5" thick slab. i'll use vertical 2x4's as furring strips on the sides of the slab to allow for drainage, but those would just be fastened with tapcons. is that too much load (skirting, 4x4 posts + railing + live load) for this type of connection?
any other tips/advice?
thanks!
#3
06-18-13, 12:31 PM
With a deck only <12" high, you won't need handrails, and quite frankly you won't have anything to attach them to, as the slab will crack and the 2x4's are too weak. Ventilation, as Joe says, is your largest nemesis. If you can figure a way to allow some spacing for that, I would build the deck without handrails.
#4
06-18-13, 01:32 PM
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thanks for the replies. the raised slab sits on a CMU foundation and is ~26" above finished grade. with the sleepers + decking, i'd still be below to 30" requirement for railings but was hoping to install one anyways.
i figured the slab would be able to support the skirting/railing. is that just too much weight?
would i be better off using post-base anchors directly on the slab if i did want to go with a railing?
i figured the slab would be able to support the skirting/railing. is that just too much weight?
would i be better off using post-base anchors directly on the slab if i did want to go with a railing?
#5
06-18-13, 01:52 PM
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here's a quick detail of what i was originally thinking for the slab/sleeper/furring layout - in case i'm not explaining this well.
#6
06-18-13, 04:23 PM
More information always trumps none 
Yes, I believe if you were to use post bases in the concrete face, spaced inward, drilled and lead anchors/lags used to secure it down, the added joisting and deck boards will give supplemental support.
A more stable way would be to incorporate longer railing posts in 6x6, then rabbet them in half for about a foot to 16", then use this tail to connect into the CMU with lags and anchors. The post would sit on top of your decking/framing, however, and would need to be fastened there as well.
Yes, I believe if you were to use post bases in the concrete face, spaced inward, drilled and lead anchors/lags used to secure it down, the added joisting and deck boards will give supplemental support.A more stable way would be to incorporate longer railing posts in 6x6, then rabbet them in half for about a foot to 16", then use this tail to connect into the CMU with lags and anchors. The post would sit on top of your decking/framing, however, and would need to be fastened there as well.
