Adding a wood deck to existing cement slab


  #1  
Old 06-12-03, 06:13 PM
stroric
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Question Adding a wood deck to existing cement slab

I would like to build a small wood deck aprox. 12' X 14' with railings, a bench seat and grow boxes. My question is can I build this on top of my existing cement slab (called a patio)? This slab is connect to the house and carport on two sides, The other two sides have small footings of about 10"sq. The cement slab has been there for 15 years and still has the same small grade for drainage. but the surface is flaking and looks like ------!

If this is posible I would like to keep the floor of the new deck as low as posible. What would be the min. additional height I would need for the new wood floor.
Richard
 
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Old 06-12-03, 07:10 PM
L
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Assuming that you leave this slab inplace, how much height do you have to work with? Are there doors coming out of the house or the carports that you need to stay under?

Done properly, the existing slab should have about 1" fall for every 10' that it projects out from the house. You will (or should be) building the deck level, so you will need to compensate for that -- very easy thing to do.
 
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Old 06-12-03, 08:23 PM
stroric
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Theres only enough slope for water not to pool. I guess it would be around 1" per 10' The entrance to the deck would be thru the breeze way of my home and carport shed. So a small step of around 6"to 8" would be no problem. I would like to ask about securing the decks beams and joists to the cement slab. Or would I need to secure to my homes foundation which would only be on the the side connected to my home.
 
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Old 06-14-03, 05:40 PM
L
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At 12' wide and projecting 14' out from the house, with about 6" of height to play with, here's how I'd do it.

Use 2X4X14's for the joists. How far you space them apart will be determined by what you are using for decking. I wouldn't attach a ledger to the house -- let the deck be free standing. Use Simpson standoff bases (ABA, ABE, ABU) and place one every 3' under each 2X4 joist. (You'll need 5 bases per joist, set at 1', 4', 7', 10', and 13' from the house. Let the 2X4's cantilever a foot on each end.) Anchor the 4 bases at the corners to the slab, and maybe 6 or 8 others. Attach EVERY base to the joist. Let the deck follow the slope of the existing slab. Put some end blocks and mid-span 2X4 blocks between the joists to ensure that they stay vertical. Use a 2X4 for your outside facia. Use the same bases to anchor 4X4 posts for the railing, and place them so they are attached to both a joist and the outside facia.

There's your substructure -- now deck it. Then finish the rails,add your seat, and the grow boxes.
 
 

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