build a deck on top of a concrete patio?


Old 05-16-01, 02:59 PM
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I am looking to build a deck in my backyard where a concrete patio currently exists.

The patio is in great shape and is about 7 feet by 9 feet. The deck I would like to build will extend beyond the patio by about 1-2 feet in one direction and 4-5 in the other direction.

I am thinking that I can attach my joists directly to the deck and forego the use of vertical posts. Where the deck extends beyond the patio I figure that I can simply cantilever the joists and again forego the use of posts, or if that isn't feasible, use posts only here where the deck extends beyond the patio.

Does anyone have any advice or suggestions? Is this feasible or am I way off base here?

By the way, we only plan to live in this house for another 2-4 years, so I am not really concerned with building a deck that will last for decades. I am more concerned with how good the deck looks.
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Old 05-16-01, 08:27 PM
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building a deck over a concrete patio sounds feasible to me

i do not know cantiliver specs but i think its something like 2 max with 2x6 joists but i'm sure its dependant on joist spacing and sizing

once you decide the size of joists snap chalk layout lines on concrete and fasten anchors into the concrete
i do not know of any 2x anchors that can be shot into concrete so you may have to use a 4x4 post base and double your joists with plywood for spacing

if you are aversed or unqualified ( in some place you need to have a liscense to use a concrete fired nailer) you can predrill into the concrete and use cut steel nails but personally ive never had any luck without the use of the powder actuated gun and you dont need a liscense to purchase one where i live

you will most likely only need to anchor the joists on either end of the patio could do it in center but up to you

the rest of the construction should go pretty smoothly

if you go with the double 2x6 joists with 1/2 x type outdoor plywood between you might be able to get your 4-5 foot cantiliver -someone else could advise better than myself

hope this helps---------josh
Old 05-17-01, 06:59 AM
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deck on concrete patio - more questions

Josh1 - Thanks for the detailed reply. That really helps.

I have a few more questions.

One thing I just thought of is that I will likely not use 2x6 joists because that would raise the deck too high above the patio, and thus above the threshold of the door to the patio. Therefore I'll probably use something much thinner like a 2x2. With this in mind I don't think I will be cantilevering the deck. I'll go ahead and use vertical posts where needed. Once again, does this approach sound OK?

You mentioned that you don't know of any 2x anchors and that I should use a 4x4 post base and double my joists with plywood for spacing. Can you elaborate on what you mean by this? I am having trouble picturing in mind what this would look like.

Thanks for any help,
Old 05-17-01, 07:23 AM
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Josh is recommending that you anchor your joists to the slab.

A 4x4 post base is 3 1/2" x 3 1/2" and two 2x's are only 3". You need an additional 1/2" to make up the filler.


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