Planning on laying my own concrete floor

11 Oct 2005
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United Kingdom
Hi i have recently ripped out my old concrete floor in the bathroom and replaced the soil pipe. i plan to hire a mixer and lay down the floor myself. I just have a couple of quick questions.

1) Should the soil pipe be placed under the damp proof membrane and then cut through the membrane to rise up for the toilet and othe waste pipes. Or on top of the membrane and in between the insulation. This also applies to the ater pipes.

2) i plan to use a damp proof membrane then 100mm insulation and at least 70 mm concrete. What is the best sand and concrete for this type of application?

thanks guys

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The decision is entirely circumstancial - there's no right or wrong.

If you can avoid cutting the membrane then it's better, but do what's best for the plumbing and drainage first and worry about the DPC second.

If you have to bring the soil pipe through the membrane then I would make a "skirt" that fits around it, coat the skirt liberally with Aquaseal bitumen paint where it touches the soil pipe, then lap the skirt over the membrane, using the Aquaseal to glue the two layers together. Then more Aquaseal on top.

| | soil | |
| | pipe | |
______/ | | \_____ skirt
________ | | ______ membrane
| |
| |

Any doubts, consult your LABC - they'll have some help to offer.

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