Another damp question

[charlied]

I have looked at the Damp FAQ and now I have a couple of questions of my own.

I have a Victorian mid terraced house. The main part of the house has suspended floors and the kitchen extension at the back has concrete floors.

We have been having damp problems in the corner of the breakfast room, at the base of an external wall. The wall has one airbrick in it and I am currently installing a second now.

The outside ground level is not 6" below the internal floor level - the outside garden area has been concreted and therefore the ground height has been raised.
I have readjusted the guttering on the outside so that is not a problem.

I have had the floorboards up whilst I put in the second airbrick and after all the heavy rain for the past couple of days, I have noticed that the ground under the suspended floor is wet - is this a problem or will it be fine to assume that with the extra airbrick it will just dry out?
If it is a problem, what can I do about it?

Would it be recommended to lower the external ground level? If so, would a small trench alongside the house be adequate? or would it be beneficial to lower the whole area?

Any ideas on the damp in the corner of the room? (There is no furniture or anything up against it)

I hope this all makes sense!
Any help or advice would be great since we don't believe that it is rising damp as the surveyor suggested, but are a bit stuck on where to go next.
Thanks

 

[PC]

Can you discribe what the damp looks like.

Is there a damp stain / is the plaster deteriorating?

Is there mould on the wall?

When did it appear?

Is it a cavity wall or solid ?

This may help with diagnosis.

If you dont believe the damp surveyor.......what did he say it was?

PC

 

[Moo]

This all sounds like the situation our son had in his SE London terrace. We solved it by hiring a skip and filling it with all the concrete (several layers!) from outside the breakfast room (a most gratifying process) and making sure that the soil was at the right level. We also had the guttering and drainpipe sorted.

The result was a dry breakfast-room wall but a sea of mud to negotiate when washing had to be hung out. Because of the strange levels involved we solved that problem by building a stepped deck down the side return passage.

 

[Lime]

I have looked at the Damp FAQ and now I have a couple of questions of my own.

I have a Victorian mid terraced house. The main part of the house has suspended floors and the kitchen extension at the back has concrete floors.

We have been having damp problems in the corner of the breakfast room, at the base of an external wall. The wall has one airbrick in it and I am currently installing a second now.

The more air circulates under your suspended floors the better. Make sure the "extra" air from your new airbrick has somewhere to go! Another airbrick on the other side of the house would improve ventilation a lot.

The outside ground level is not 6" below the internal floor level - the outside garden area has been concreted and therefore the ground height has been raised.

That is a problem.
The outside ground level needs to be as low as possible.
If concrete is needed to combat mud etc then the soil needs to be removed before the concrete is poured so that the level is no higher than the original ground level. Remember rain splash is increased when it falls onto a hard surface. Also the concrete needs to be sloping away from the house so that water is taken away from the house and the underfloor.

I have readjusted the guttering on the outside so that is not a problem.

Ensuring that the guttering, downpipes and drains are not contributing to your damp problem is most important.

I have had the floorboards up whilst I put in the second airbrick and after all the heavy rain for the past couple of days, I have noticed that the ground under the suspended floor is wet - is this a problem or will it be fine to assume that with the extra airbrick it will just dry out?
If it is a problem, what can I do about it?

Yes it is a problem.
The water must be coming from somewhere.
If it is from outside then making sure rain is taken away from the house should sort out the problem.
Are you sure it is not flooding in through any air brick?
Are you certain it is not a leaking water, drain or sewer pipe?

If you make sure that a good draught is blowing under the floor it will dry the underfloor subsoil but it is better to prevent it's ingress if possible.

Would it be recommended to lower the external ground level?

Yes.

If so, would a small trench alongside the house be adequate? or would it be beneficial to lower the whole area?

I would lower the whole area if you can. A trench is used where it is not practical to do otherwise.

Any ideas on the damp in the corner of the room? (There is no furniture or anything up against it)

It is too early to say as the problems of high outside ground levels, concrete leading water under the house and poor ventilation need to be dealt with first.
It will need time to dry out properly.

I hope this all makes sense!
Any help or advice would be great since we don't believe that it is rising damp as the surveyor suggested, but are a bit stuck on where to go next.
Thanks

Yes, it sounds as though you know what you are doing and what you have to do.

 

[NT]

Wet soil underfloor is normal, the problem is if it has standing water. If so, probably water is draining into there somehow. Either that or youre living in a bog!


NT