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Groundwork & Foundations

Thickness of suspended concrete slab under flat

Anonymous user 09/03/2024 - 3.02 PM

Hello – I live in a purpose built ground floor 1960’s flat with concrete floors. My concrete floors are damp in places in the bedroom and lounge. I have high humidity and a strong smell of damp in the lounge especially when it is cold and rains. I also get some black mould and as it is such a cold flat I will be drylining the walls eventually. The floors are suspended concrete and an inspection by an engineer recently when the foundations were exposed revealed that the suspended concrete floor under my flat was between 27 to 30cm and showed a surface crack and eventual chip in the surface of the slab. His inspection showed that the other flats had a concrete slab of 35.5 to 40.5cm. However he didn’t go on to comment as to whether my flat would be more affected by damp as a result of a thinner concrete slab. None of the other flats gets problems with damp concrete or high humidity. There is not a damp proof membrane under the concrete slab. Can anyone tell me please whether I am getting these problems because of the thinner concrete slab and no DPM. I know that nothing can be done about the size of the concrete slab but I am hoping that the management company might agree to do something internally for me on the floor. Thanks very much.

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4 Answers

KDR LANDSCAPES AND PAVING

Rating: 5 out of 5
Bury
All internal concrete slabs should have membrane under, if not some would get damp some may not .The thickness of concrete is not really the issue no membrane is .Also high humidity could be many factors such as bad circulation, no air bricks not opening windows no extractor fans in bathroom or kitchen broken drainage above or below ground roofs leaking in to cavity no cavity trays .Should start by resolving this issue with cheapest options first such as window on venting installing air bricks then possibly extractor fans and see how this works . Karl
Answered16 June 2019
3

Prestige cellar and joiner services

Rating: 5 out of 5
Tranent
No membranes under the slab no matter how thick will give you those problem ,a thin surface membrane or epoxy resin to stop dampness coming through to begin ,then have a look at air circulation/ humidity in the property
Answered16 June 2019
0

Anonymous user

If you have a sufficiently high ceiling the solution would be to lay a DPC membrane and cover with a screed layer of at least 40mm then to damp proof the walls Upto 450mm with damp proof spray then stud the walls using moisture resistant plasterboard. PVA these and skim. Also air ventilation is essential so ensure that air can escape at the higher levels of the property.
Answered16 June 2019
0

Anonymous user

Your problem stems from not having a DPM in place And not from the slab size
Answered17 June 2019
0