DIY Doctor

DPC above or below concrete slab??

Postby old stilly » Mon Feb 02, 2009 9:36 pm


We are currently renovating an old brick built house and have so far stripped it bare, dug out the floors, stripped all plaster off etc.

the house is sitting on sand and gravel and hasn't moved/cracked in the last 300 years. We need to underpin certain walls but the rest seem not too bad.

We'd like to pour our concrete slab direct onto the floor to allow the concrete to go into all the remaining nooks and crannies at the bottom of the walls.

then we'll blind it off with sand, DPC, insulation and finish off with screed/ water UFH. Can anyone advise me whether we're doing the right thing - our architect doesn't seem fussed either way!!

many thanks :)
old stilly
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Simply Build It

Postby stoneyboy » Wed Feb 04, 2009 10:12 pm

old stilly,
Shoot the architect.
Old houses depend on a large amount of flexibility in their walls, I doubt that cementing the lower part of the wall to a concrete slab will be beneficial. Without seeing the subsoil composition it is difficult to recommend a suitable floor structure. At least I would have expected you to get a recommendation for compacted hardcore, sand blinding, DPM (lapped up walls), concrete slab, insulation and floor finish.
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