Damp patch in middle of solid floor

[RzB]

During some refurbishment work we have removed all the floor coverings from the kitchen, dining room and hall, in preparation for latex self levelling (All solid floor). The hall was covered with carpet under which were small wooden blocks (parquet flooring). These were stuck down with black bitumen like adhesive.

Over the weeks of refurbishment the tackiness of this black glue has been annulled by the copious amounts of dust that have been produced. However this dust layer has show up a worrying patch of what appears to be damp.

The weird thing is that it's right in the middle of the floor. It has slowly grown to about 3 inches in diameter. No sign of damp anywhere else. There are no buried pipes in the floor.

Nice pictureof the damp patch here... :-)

have a suspicion that when the house was built in 1963 there was no damp proof membrane laid below the solid floor. Some years ago I dug a hole through the dining room floor and found no membrane.

What should I do? Ignore it - it's not been a problem in the last

18 years :-) Or perhaps dig up the offending area and fill with an SBR & concrete mixture? Or what... ?

Thanks, Roy

[The Natural Philosopher]

Then either its not damp. or there is one below the floor..think..soil under a house is dry except where the rain gradually seeps under it In which case the edges would be damp if its lack of DPM.

The only think it might be is a hole in the DPM.. or a leak.

I'd probably ignore it., but if it worries you dig it up and see.

[Ian Middleton]

A friends house built in 1971 had corroded central heating pipes causing a damp patch in the concrete and mould on carpet. He cut pipes out using angle grinder and replaced with 15mm copper sleeved in 22mm plastic pipe, PVA'ed and concreted over and problem solved apart from the concrete dust falling our of lounge furniture for ever more !!!!!