Damp underlay

Jenferdog

Hi, hoping someone can advise on this. We recently bought a 1970's bungalow which has asphalt flooring. We are currently decorating one of the bedrooms and lifted the carpet and underlay to paint skirting boards to find that the underlay along the outside wall is very damp, not wringing wet but wet enough to leave damp patches on trousers when you kneel on it. The carpet itself was dry and didn't feel wet to walk on with bare feet, and there is no mould or damp on the walls but sometimes there is a definite musty smell. The radiator used to be under the window on that wall but we had it moved. I am hopefully suspicious that there has been a leak at some point there from the old radiator but also is it normal for condensation to form on top of asphalt? There is a lot of condensation on the new double glazed windows every morning. TIA 

stuart45

It can form on top of the asphalt as it won't soak into the floor.

Apodemus

stuart45 said:

It can form on top of the asphalt as it won't soak into the floor.

...and often can't "breathe" through the underlay.