Damp after building work

hjc1985

Hello,

So I’ve just had an extension built and currently in the final stages. We’ve painted this weekend and noticed small areas of damp in the concrete floor only in the corners of the room.

The plaster and concrete floor took a long while to dry out due to snow and the heating has just gone back on.
Wondering if this is likely to be damp left over from the walls and floors drying out ( perhaps moisture deep within the structure working its way out) or if it’s a sign of something more sinister. Can anyone help?

The damp changes shape slightly throughout the day, is only in the corners of the floor where there are outside walls and is clear (no brown staining etc)

Other things to mention is that the outside render is yet to be completed and the damp patches aren’t close to any plumbing etc.

New to this forum...I do have pics but unsure how to attach them 😣

DaftyDuck

Just had? I reckon it takes a month for a walk to dry, two to four months for a reliably dry floor.

That would be with good weather. Just ball-park figures, but I'm guessing they aren't the same as "just"....

kev25v6

I bet the insulation in the walls got soaked while building and will be working it’s way out at the bottom.

hjc1985

Thanks both to comments. Yes, this is all very recent and the builders are still not finished...they’re still in the house and due back after xmas to finish the render.

Trying to decide whether we need to start a negotiation with them so this is helpful

DaftyDuck

So, how long since the plaster was put on the wall, and how long since the floor was laid?

If the render isn't finished, it's possible (but unlikely) that the wall is not fully sealed.


You may wish to discuss the causes with the builders, but it's not time yet to stamp your feet (too) loudly.

hjc1985

Thank you.

Plaster has only fully dried in the last few days because of the snow and wet weather. Flooring was laid 1st December but again took ages to dry.

It is lined and insulated underneath the slab and we know this because we saw it before the concrete went in. The kingspan was left in the rain and is in the floor and walls so maybe only just drying out?

betsie

Screed takes ages to dry fully depending in the thickness but can be 2-3 months and longer in the winter. So defo don't start moaning at the builders.