damp patch

[gas01]

I have taken up my old floor in my extension - which has a concrete base and in the corner of the room there is a damp patch, near the outside wall on the floor. Not on the wall just the floor.

I have noticed it after some heavy rain and am waiting for more rain to see if i can see where it comes from. it looks to come from outside rather than underneath, as it grows slowly and spread out about 8 inches.

The is a damp proof membrane i can see under the floor from outside.
The exterior is covered by tiles and under that wooden frame with some kind of felt covering. The felt covering at the bottom is torn and worn away so i'm thinkng maybe its from there.

Does anyone know what this felt might be so i can buy some and replace it or go over the top of it.

I'd also like to buy some kind of damp seal to paint over the damp patch as a secondary caution, just to be on the safe side. Any ideas on best one from b&q

I will also put a damp proof membraine down before i put my underlay down for my laminate, just to be on the safe side !!

Thanks for any advice given.

 

[JohnD]

If your outside wall is clad, and the cladding is damaged, it may be that water is running down it and dripping onto the top of the dwarf wall, then moving into the floor.

If you are mending the felt and tile, see if you can kick out the bottom a bit so that drips tend to fall outside.

If the wind is blowing rain against cladding then quite a lot of water runs off it.