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tripitaka888
12th January 2008, 11:42 PM
Hello

my kitchen/bathroom were completely rebuilt on a new concrete slab about 3 years ago. I don't know what kind of slab it is (raft slab/waffle slab?) It is basically a large slab of formed concrete on black plastic with reinforcement inside the concrete. The slab is about 10 inches high/thick (from the ground) when viewed from the outside.

Where exactly should the earth/dirt/gound level be near the slab? I can dig it out if need be - I have adjacent neigbours on a standard 400m sq block.

Should it be on the same level of the black plastic - ie. to decrease the amount of moisture that may 'seep' sideways into the slab?

Or should be be a few inches up the side of the slab - ie. a few inches ABOVE the black plastic, yet a few inches below where the bricks start?

Or should it be on the same level as where the bricks start - ie. the foundation completely "under" the level of the ground?

I certainly would appreciate any advice as I want the longevity of the slab to be as long as possible.

With thanks

AC

Dirty Doogie
13th January 2008, 12:39 AM
All will fine if your finished ground level (including mulch) is about 100mm below the top of the slab. This is so you can see if insects or termites try crawling up the side of the slab and into the house.

It sounds like you have a pod slab. I wouldnt be worried about water entering sideways through the concrete but you could always put a strip of fibrous cement sheet against the side of the slab.