Room smells of damp plaster after rain?

[dododoing]

We've recently taken up the carpet in a downstairs room and took the skirting boards up at the same time. Had the room replastered, and put down a foil backed underlay & engineered wood floor. The skirting boards haven't gone back yet, and the plaster doesn't go all the way down to the floor around the edge of the room (where the old skirting board was). Now every time it rains we get a really really strong smell of damp plaster in the room. There's no obvious damp anywhere in the room, we're not getting any mould, just this really strong smell - although I haven't checked with a meter, just felt the walls.

The room has a concrete slab, it's brick and block wall construction, with no cavity wall insulation. Immediately outside this room the previous owner has raised the level of the patio so there's probably about 10cm clearance for the DPC.

I guess my question is, is what we're smelling possibly plaster or brick in the outside wall/cavity getting wet? And if we go around the edges of the room making sure there are no gaps for air from the cavity to get through, will be solve this problem? Or should we be investigating more? And if filling is a good idea, what would be the best thing to fill it with? Just more plaster, polyfiller, foam? Anyone got any ideas?

I think if there was water ingress, the lack of skirting board would make it obvious. Are all the windows closed when it is raining? The plaster could merely be absorbing consensation within the room?

My initial reaction, given what you have said & subsequent to you checking the situation with a damp meter, is to get a big tin of Thomson waterseal ultra & apply it to the exposed brickwork under the plaster before the skirting boards go back on & on a couple of courses of bricks above the patio level.

The windows are closed when it's raining. I can feel a draft coming from the bottom of the wall where the plaster doesn't go all the way down, if you see what I mean, which is why I thought it might be a smell coming in from the cavity. No signs of water coming in.

Will definitely get a damp meter - if the plaster is absorbing condensation, is there anything we can do about that? And why would that be just when it rains? Surely we'll be producing a fairly consistent amount of water vapour inside the house?

Hadn't considered something like waterseal, so thanks for that.

Now pondering whether a drain survey would be a good idea too - as far as I know, the drain runs past this room and that could explain why this is more of a problem when it rains?

Its a pity the new floor is already down, I'd be interested to know if it is damp under the floor. If it has a downpipe or gulley by the wall it may be cracked.

Building regs require at least 15cm clearance between ground level and DPC. We had this problem in our current house. they'd also covered the air bricks that ventilate our suspended wood floors, so we decided the best option was to return the patio to its original level.

There were vinyl tiles under the carpet, PigletJohn - we presumed they were asbestos so left them be as the floor was pretty level, but there weren't any signs of damp under the carpet/under the tiles (some around the edges of the room were cracked where the carpet gripper had gone in).

We had a lot of rain yesterday and the smell was really bad - had the window open today and no rain, and it's gone again.

I've ordered a CCTV of the drains for a couple of weeks time. Shouldn't be any problems with the gutters (no downpipe near this room) as we renewed them last year, but I guess that's something to check again next time it rains.

Will think about taking up the patio slabs too then!

Brownsauce, did you have just this problem - the smell of wet plaster after rain?