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DIYfamilyman
Composite deck over concrete patio?

My threshold from the house to the concrete patio slab is 3". I want to put a Trex like deck over the slab. The slab is approximatly 16'x16'. I have read that adding a deck with such low cleareance is a bad idea due to mold. I live in Orange county, Ca and it is pretty dry. Little rain and less humidity. I was thinking of running treated 2x4's flat for and inch and a half height then adding the 7/8" Compostite on top with hidden t-fasteners. What do you think? Tearing up the concrete is really not an option.
Could I put some kind of 1/2" or 1/4" blocking under the 2x4 joists if you will to help with air movement?

With the 1.5" 2x4 flat and the 7/8" composite deck I only have about 1/2" left over before I get to the level of the house threshold.

MLB Construction
Re: Composite deck over concrete patio?

sounds like a good plan to me. no need to put anything under the 2x4's as long as they're pressure treated

DIYfamilyman
Re: Composite deck over concrete patio?

How would you suggest I fasten the 2x4's to the patio?

MLB Construction
Re: Composite deck over concrete patio?

build a framework with sleepers 16" on center and screw or nail it together. use a ramset or concrete anchors to secure the sleepers to the concrete after you have your frame all together and squared up.

A. Spruce
Re: Composite deck over concrete patio?

I have done this very thing, though I wouldn't use PT 2x4, I would use solid Trex. While Trex is not structural, it doesn't have to be in this instance, you're getting all that from the concrete patio.

dj1
Re: Composite deck over concrete patio?

I would use composite too and seal the outside so no unwanted/nonpaying tenants move in under the deck.

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