damp floor

juraj.kecso

Hi All,

I have a slight problem,which I was hoping I could get some advice on.

We are currently in the process of renovating our small dining room. It's a 3 bed semi built in the 50's.

After removing laminate flooring I discovered that floorboard in one corner were a bit dodgy. I pulled them up and discovered the wall was quite damp (it hasn't rained in a while). This has obviously affected the joists, which are slightly damp to touch and also the wooden part of the sleeper wall supporting the joists, which is actually starting to crumble around edges.

I called in my local builder, who said that this may be down to the cavity below DPC blocked, which causes water to seep through to the inner leaf.

I am not sure what to do. He suggested that he could cut a trench around the building to stop further water runoff from a concrete path around the building saturating the brickwork.

Is there anything else I can do? Is there any way to clear the cavity? He did say that houses built in that era often have cavities filled by debris left after lazy builders and such.

What about the damp flooring joists and sleeper wall? The builder mentioned dehumidifier from plant hire companies, but that that will only dry the walls and woodwork for now, not solve the problem.

I was planning to lay down new engineered wood flooring this weekend. Now I really don't know what to do. The last thing I want is for the floor to cave in one day.

I can deal with some small diy stuff, but this kind of problem is just beyond my capability and
comprehension of where to even begin.

stuart45

juraj.kecso wrote: »

I called in my local builder, who said that this may be down to the cavity below DPC blocked, which causes water to seep through to the inner leaf.

Are you sure he didn't say the cavity might be blocked above DPC. The cavity is normally filled about 225mm below DPC(used to be 150mm in the 50's)

troffasky

Where to begin, is with stopping the water at source. No point attempting anything else [other than shoring up anything that looks like it's about to give way] until you've done that.



How is your guttering? Any signs of damp on the outside of the wall [eg moss/green on the wall? Where does your water supply run? Waste pipes?


Do you own the concrete path? How certain was the builder about that being the source of the problem? Does the path fall towards your wall?

markin

Need lots of photos inside and out.

FreeBear

stuart45 wrote: »

Are you sure he didn't say the cavity might be blocked above DPC. The cavity is normally filled about 225mm below DPC(used to be 150mm in the 50's)

Admittedly, my house is a little older, but... The walls below the DPC are solid, and the cavity only starts at the DPC. So any debris that falls in to the cavity will bridge the DPC.

For the OP, short of removing a brick or two, the only way of checking the cavity is to drill a hole and insert an endoscope - You can get some very cheap little cameras to plug in to a phone or laptop that could do the job. The source of the damp needs to be fixed, then the joists & floor repaired, then you can lay the flooring.

stuart45

FreeBear wrote: »

Admittedly, my house is a little older, but... The walls below the DPC are solid, and the cavity only starts at the DPC. So any debris that falls in to the cavity will bridge the DPC.

That's why the cavity is normally left clear 3 brick courses below DPC. It used to be 2, but by the time the brickwork was plate high it was often found that the mortar droppings were above DPC. Using cavity battens during the build, or leaving out coring holes and a end of day clean out was sometimes used to stop the problem.

juraj.kecso

He may have said above blocked above DPC, I am not sure now.

I almost started crying when I saw it.

He was fairly certain that outside bricks are saturated due to concrete slightly sloping towards the wall. It ends right at the wall. He mentioned that cutting a trench around should then stop more water saturating the wall. He also mentioned clearing the cavity by removing bricks and using a dehumidifier whilst I wait for the trench to be cut.

I suppose the problem with the floor was caused by some of the woodword touching the damp wall and sucking in the moisture.

Why can't they manufacture joists from plastic?

Would I be able to claim some of the costs on my home insurance?

FreeBear

juraj.kecso wrote: »

Why can't they manufacture joists from plastic?

Would I be able to claim some of the costs on my home insurance?

Wood is by far the best material for joists. Cheap, recyclable, green. Plastic is none of those.

As this is a maintenance issue, your house insurance would (quite rightly) refuse to pay. Do as your builder suggests - Remove concrete 200mm away from the house, install a French drain, check the cavity, and repair the floor. Sounds like this builder has some idea about fixing damp problems rather than flogging snake oil solutions. Take head of his advice.