Plasterboard tent

[middleagedriver]

Hi,
Recently moved into a new house build 1996. Sharp realised the walls are freezing. Went into the loft to check insulation and discovered we have gaps going’s down all external walls behind the dot and dab plasterboard. This coupled with lots of drafts and high humidity of 65% RH inside the house when foggy or raining (too much air ingress)

Seen a few post about putting expanding foaming in gaps and sealing them up. Is there anyone that had success with this? Just wouldn’t want to waste a few hours if if doesn’t work.

 

[JohnD]

Draughts from outdoors do not raise RH.

Assuming your house is heated, and warmer inside than out, fresh air will reduce humidity, even on a cold rainy day.

The most common cause of damp in UK homes is wet washing draped indoors or hung over radiators, and bathrooms lacking effective extractors.

Damp can also come from leaks, in the roof or plumbing.

A house of your age should not have faulty walls or DPC.

Which rooms are bad, and which part of the walls? Some photos would help (of the whole wall, not just the damp patch).
Go in the loft. Is the roofing felt wet on a cold morning? What about a sunny afternoon?

Is yours a timber-framed house with brick skin, or does it have cavity walls?