Building on top of a slab


Old 08-12-16, 01:15 PM
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Question Building on top of a slab

when building ontop of slabs what must be placed down first in order to make everything level and safe.

thank you.

this is for decking. Cheers
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Old 08-12-16, 01:42 PM
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Welcome to the forums.

Sorry, need a whole lot more information and details to understand what you're asking.
Old 08-12-16, 02:37 PM
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Deck on Slab

If you talking about deck joists directly on the slab, then you need to locate the highest point of the slab and shim all joists to be level with the joist(s) located at the highest point.
Old 08-12-16, 02:45 PM
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..... but it isn't a great idea to build a deck just over a slab as rain water can get it but lack of ventilation prevents it from drying out in a timely manner = short life for the deck
Old 08-12-16, 02:58 PM
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Just a really bad idea!
What's wrong with the slab now?
There's been hundreds of people showing what happens when this has been tried on this and any DIY web sites.
Joist and decking rot out, decking is so high water gets in under the threshold and takes out the flooring or more inside the home.
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