Damp Proofing Question

Mould on carpet following laying of screed floor

In May/June we had repairs done to our property including brickwork repairs, laying of a screed floor on top of an existing concrete base and redecoration to our dining room.

Since that time we have noticed areas of mould (white, furry patches or darker dust like patches) on the carpet in this room. Since the work was completed the room has been empty of furniture, the curtains have been put back up and the room hasn't been used.

A fortnight ago I went in there to find these patches on the carpet. I immediately vacuumed them up, went on holiday for a fortnight, have come back and mould has regrown but not as extensively as it was a fortnight ago.

There isn't any evidence of mould anywhere else in the house and is only on the carpet in the room, and we haven't had this issue prior to the work being done. Logic tells me that it is to do with the floor. The screed was laid 18 days prior to the carpet and underlay being relaid. I don't know much about the screed other than it contained fibres and was like a dry cement substance.

Any advice?

Since this posting, we have now lifted the carpet and underlay and there isn't any sign of mould either on the back of the carpet, underlay or on the surface of the screed!

We have now a hygrometer and humidity in the room at the moment is around 67% and going up. As the only thing new is the floor, what should our next step be? There are obviously raised moisture levels in that room causing mould to grow on the surface of the carpet. As this work was done as part of an insurance claim, we are not sure what our next steps should be. The builder who the insurance company appointed arranged for the carpet to be lifted and is now happy that there is no obvious sign of moisture. However, from our part this problem has only arisen following the laying of the floor. Any further advice for me?

2 Answers

Best Answer

Could be damp from the screed.Depending on thickness of screed,type of cement used etc,18 days is probably not long enough to dry out properly.

Answered 22nd Aug 2012

Roc builders

Member since 25 Aug 2011


RHI 65 %

Screed on top of concrete

Is it a wool mix carpet

Was it a latex/ water based screed

Loads can effect the RHI. Get a profesional that knows what they are doing. Was the Hygrometer in situ on the sub floor for 72 hours. Not one in the room, if the floor levels are high, then that is your problem. Possilble liquid LDM could be used, but if already got a damp problem in a wool mix then !!! If the room 75% is high thats your problem, if that makes sense ? ?

Answered 7th Aug 2014


Member since 4 Aug 2014

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