Damp patches on concrete floor?

[tj]

Hi

I have a problem for the lateral thinkers out there, Gluestick, I think your among that number!

A room, that has as its rear wall, an adjoining barn which more often than not has a damp earth floor, since the roof does leak a little, the oneside wall of the room adjoins a small house which suffers the same damp earth floor problem as the barn. The house has a 4m x 1m space to the rear bounded on all sides by stone walls of the neighbouring building and of course its own. the ground level in that space is approx 60 cm higher than the interior floor level.

keeping up with this !

At one time, given the above situation, some hours after heavy rainfall damp patches would appear on the concrete floor of the room in question, no surprise I guess.

One problem that fuelled this problem was an old disconnected rainwater pipe, after repair the problem seemed to have been solved.

So the problem today, bearing in mind the last rain the house saw was saturday night and nothing much really, damp patches started to appear in the room yesterday and have got worse over the last 24 hrs, not pools of water but glistening patches her and there, and not all connected to eachother.

My question, since the temperatures have soared over the past few days, could the raise in temperature be actually drawing moisture upward, and that previously it didnt suffer the same damp patches for the opposite reason that it was not so hot?

any comments welcome

ps, in general the house interior floor level is 2 steps below outside ground level.

 

 

 

 

[Dick Smith]

Could well be water coming up from beneath the floor. We had the same on a concrete floor (above ground level by a few inches), and when it was lifted it was found to be no more than a thin screed over stone rubble. It seems likely that the water was drawn up between the stones by a sort of capillary action. We cured it by having a proper floor laid. This never happened in hot weather, but did appear a few hours after rain or in very cold, damp weather.

[trees 2]

The short answer is yes, the water could be being dawn up by both Dick's capillary action and the temperature in the room above. The warmer the air in that room, the more moisture it can hold.

[WJT]

TJ, this is currently being discussed on another forum and in fact I have just tried this and it worked! To find out if it is condensation or rising damp put down a polythene sheet and if it becomes wet underneath it is rising damp and if it becomes wet on top it is condensation. I used black plastic bags with pieces of tiles to hold them in place and they were wet on top so confirmed to me that it is condensation.

[thunderhorse]

With the past couple of days being so hot and humid, and the cement floor at the back being a lot cooler, we can see the moisture condensing out. The neighbour next door has suddenly seen his new wallpaper glistening. Very humid indeed.

But I'm going to try the plastic sheet trick anyway.