basement moisture barrier or polystyrene to fix rising damp

Filed under Damp and Mould, Ventilation and Air Quality, Ground Moisture.

March 23rd, 2009

We have a house built on very damp ground and springs emerge from the bank under the house now and then. We are installing more drains to drain a pool of water. Once this is completed should we install a polythene moisture barrier and line the underfloor with polystyrene, or can we just seal the basement concrete ring wall and line the underfloor with polystrene?

2 Comments

editor, March 23rd, 2009 on 9:07 pm

Our advice is that as long as there is no risk of water ponding on the surface of the polythene, the polythene vapour barrier is a high priority. Reducing the humidity under the floor can be achieved reasonably cheaply with polythene (assure that it is taped to the piles and runs up the concrete walls by 50mm). If there is any way to improve the ventilation under the floor, by clearing the ventilation grates or cutting new ones, this will also help. Reducing the moisture content of the subfloor will enable the house to be heated more easily. This combined with underfloor insulation (polystyrene, polyester, fiberglass etc) will give the best solution.

Phil Squire

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Peter Jackson, October 11th, 2010 on 10:35 am

Hi,

I also suggest you that as long as there is no risk, you can go with the polythene treatment and if it is not working, you have to change the treatment style. To treat the rising damp, the first and foremost thing you have to do is to detect the leakage sources. If the is water penetrating you need to treat this and sometimes it has very bad affects on the walls. There will be signs of salt on the wall and the results are so bad that the paint and the plaster began to fall. You can install the DPC (damp proof course) as a remedies so that the problem will not appear again.

Good Luck

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