Need help planning deck


Old 07-02-16, 01:30 PM
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Need help planning deck

I want to build a deck over an existing 10'x10' concrete patio, and extend it so it is 18' wide. The area I want to extend it to is sloped down (19"). I also have to contend with a basement egress area.

I have designed a deck using an online tool, with a notch to accommodate the egress window, but the fact that it will be partially on concrete is confusing me with regard to the placement of posts.

I have attached two pictures. 1 is the deck plan without the placement of the existing concrete patio. The second picture shows where the concrete patio is (Ignore the writing "house", the online tool I used didn't have anything I could use to mark the area other than a house graphic).

How would I build this deck, considering the placement of the concrete patio?

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Old 07-02-16, 01:52 PM
Join Date: Jan 2011
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Got a real picture of the outside where you plan on building this?
Just a bad idea to try and build a deck over an old slab for several reasons.
The joist are not direct contact rated and will rot out.
Not enough air flow under the decking to dry out.
A slab moves, a deck should not.
There may be more reasons with a real picture, one being that decking needs to be at least 6" below any door openings
Old 07-02-16, 05:53 PM
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As Joe mentioned, putting a deck on top of a concrete slab is a bad idea unless sufficient clearance allowed for air movement. Even if you take the slab out you want to make sure you have sufficient air clearance between the deck in the ground. If you have sufficient clearance you may be able to just cut a hole through the slab to put in footers for the posts that will support the slab.
Old 07-02-16, 07:14 PM
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Here is all things Deck related as far as your codes are concerned - These codes are printed for the US, but should pertain to Canada or at least prove to be a good guide to reference. Check your local code office for more specifics. Sometimes they have printouts of these codes for you at the permit office.

How high is the deck off the ground? You talk basement so it is confusing. Do not attempt to use he concrete patio in anyway to anchor the deck. The patio is only 4" thick and not structural to hold up a deck. You need to dig footers to the proper depth to get below the frost line.

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