Lowering external ground level 6" due to damp

[DIY Novice]

I've been told I need to do this due to damp in an area of the house at the rear which has a concrete floor. The external area currently has paving slabs. I could take all of these up and re-lay them having removed 6" of soil but as the whole paved area is about 25M sq this would be quite a lot of work and require serveral skips to remove the soil. I'm thinking about lifting the slab nearest the wall, remove the soil close to the wall and replace with bricks (but leaving a gap of 1" or

2" between the bricks and the wall for ventilation purposes), then replace the slab.

Will this work and has anybody done anything similar?

[Peter Taylor]

You don't say where your paving level is in relation to the dpc, but I assume they are about level. In new build situations the Building Regs require the ground level to be 6" below dpc - the reasoning for this is that rainwater can splash up that far, especially from a hard paved surface. So if you plan on keeping the paving slabs at the existing level and having only a 1" gap between them and the wall this won't help at all.

The normal way of getting over this is to form a channel or trench against the house wall, at least 6" wide although 8" or more would be better. The bottom of the channel must be at least 6" below dpc level. A bed of gravel or shingle can then be laid in the channel up to say minimum 2" below dpc. This allows rainwater to drain away below dpc level and does not cause the splashing problem.

HTH Peter

[Christian McArdle]

Should work fine, particularly if you have gravel soil. If you have clay, you might find it just acts like a pond and you need to supply proper drainage to prevent puddling. This is frequently not difficult to supply, as a gutter downpipe is likely to run nearby which might be suitable.

Christian.

[Victoria Clare]

[e-mail] (DIY Novice) wrote in news:83554807.0406010342.58d96114 @posting.google.com:

My house's back wall is separated from my garden by such a gap. The wall is a bit damp, because over time dust, leaves etc have washed/fallen into the gap (about 4 feet deep, but less than 1" wide!).

A gap only 6" deep & 2" wide would be easier to keep clear, but you may want to make it a bit wider so you can get a trowel into it.

[Christian McArdle]

I've used a old wooden mop handle to clear out such spaces. It would probably be even more effective if the rounded end was shaped into a scoop.

Christian.

[Ian Stirling]

A cacuum cleaner set on blow, with an appropriate crevice tool (made from whatever pipe is handy and will fit into the hole) ma be ver handy.

[Andrew Gabriel]

I had pretty much the same situation. Actually I still do, but the damp has gone without doing anything to the outside at all.

I did two things, and I'm not sure which cured the problem. Firstly, I installed central heating. Previously the heating in the house was uneven and it was the colder areas which got damp, so it could have been condensation in part.

Secondly, I replastered the damp areas using a sand/cement/lime/waterproofer scratch (base) coat, and the damp will not penetrate that even if the wall itself is still slightly damp.

The other thing is to keep a careful eye on the external pointing where the water splashes up the outside wall. It will likely need more frequent attention than the rest of the pointing, and if it is allowed to deteriorate for long, the bricks could become damaged. However, seek advice here or elsewhere before slapping just any old mortar mix in, as the wrong mix could damage the bricks even faster.

[Jerry Built]

Don't forget that the DPC may be bridged internally as well as externally.

J.B.