Damp floor boards

[DIYdampbusting]

We've recently moved into a 1870 Victorian terrace and have been struggling to resolve some damp issues in our living room.

The symptom of the damp is wet floor boards around the edges of the room where the wood touches the wall after heavy rain. The wood is dampest on the outside wall, but we've also got wet floor boards on internal walls.

The construction of the house is sandstone, with a suspended wooden floor over the dirt. There's a gap of around 1.5m between the floor and the dirt. The air bricks are all clear; ventilation is good at the front of the house but poor at the back. The soil under the floor is dampish to the touch.

On the advice of our surveyor we had a chemical damp proof course, but didn't seem to do much to improve things. We eventually found a drain at the front of the house was blocked, and after that was cleared things improved. But we're still getting damp where wooden floor boards touch the wall. Any ideas what's causing it?

My theories so far

Rising damp- the chemical damp proof course should have fixed this issue...

Penetrating damp- unlikely because we're also getting damp floorboards on internal walls

Condensation?

My plan is to cut back the floor boards that touch walls and then fix some damp proof material between the all round the room between the floor boards and the wall. And also to improve underfloor ventilation with extra air bricks. How does this sound?

Any advice would be very much appreciated.

 

[gregers]

My plan is to cut back the floor boards that touch walls.
And also to improve underfloor ventilation with extra air bricks. How does this sound?

thats what i would do.then wait and see if it cures it.

 

[DIYdampbusting]

Thanks for the help. Do you think this is most likely to be condensation?

 

[gregers]

couldnt tell you m8,as i havnt seen the job.but introducing more sub floor ventilation should help the situation and hopefully help to solve it???

 

[pinenot]

Think about this for a moment, the house has stood for over a hundred years, obviously without any great deal of damp, otherwise the floors/walls would have rotted or worse. So you need to identify the real problem - whats new - you have already mentioned the injection of a chemical damp proof(sometimes a bigger problem than left alone) a blocked drain (albeit cleared) what else is there, regardless how insignificant it may sound??

Have the external walls had any work done to them - has any cement/concrete been used nearby, or any rainwater rhones/downpipes bean fixed/replaced ?

 

[DIYdampbusting]

To try to eradicate the damp, we've done the following:

Replace leaking down pipe
Cleared block drain (in January)
Chemical damp proof course
Stone work repointed


The differences in the house compared to when it was first built are

Double glazing
Extension to the back (possibly early 1990s build but not newer) when this was carried out I believe 1 airbrick was removed from the back of the house.

I'm pretty vexed by what's causing it

 

[pinenot]

Can you broaden out "stone repointing" was this done with cement mortar by any chance?