Homebuyers Report: Dampness

[meow2222]

If you want to solve it try

NT

[Maris]

I'm not sure I saw any obvious clues as to how to solve it but lots of comments backing up my thesis. Thanks anyway for a very useful website. My only strategy will be to lower the ground level ouside, which is above the level of the inside floor level.

Maris

[Ed_Zep]

Does anyone agree that living near the bottom of the hill can make rising damp much more likely?

[Stuart Noble]

On clay soil quite probably

[Grimly Curmudgeon]

We were somewhere around Barstow, on the edge of the desert, when the drugs began to take hold. I remember Maris saying something like:

That'll be it. I'd be surprised if it's anything more than that.

[meow2222]

Lowering the ground level is a good move. Re the website, have to try a bit harder if you want results.

NT

[Maris]

Unfortunately that can't be applied to the party wall, which also has the problem.

Maris

[John Rumm]

I would have thought there is less chance of it raining in the neighbours front room though...

[Stuart Noble]

This is where the argument against rising damp comes unstuck. On an internal wall you can eliminate condensation as the source by increasing heating and ventilation but, if that doesn't work, what are you left with?

[Dave Plowman (News)]

Installing a damp course to a party wall would involve disruption to both parties since there's little point in providing a new one of any type if it is bridged at one side by porous plaster.

Before accepting it *is* rising damp the obvious check is if it is showing on the 'other' side.

[Maris]

Unfortunately, my neighbour is not very au fait with building methods but he seems to think it has been tanked on his side after he had lots of problems with damp too. That would, of course, ensure that all of the damp emerges on my side. Not sure about the legal situation there! In any case, I have stripped back the hard render to allow the wall to breathe and dry out.

Maris

[Grimly Curmudgeon]

We were somewhere around Barstow, on the edge of the desert, when the drugs began to take hold. I remember Maris saying something like:

Ask your neighbours to stop using it as a urinal.

[Dave Plowman (News)]

What's the construction of the party wall? How much of it is below floor level?

[Maris]

It's a 13 and a half inch brick wall, built of mainly multi stocks. It is, like most Victorian houses in London, built on brick spreaders, which may extend to about 50 cms deep below lower ground floor level.

Maris

[meow2222]

That may well turn out to be enough, though it can take a long time to dry right out. If it works, using a porous finish will enable it to evaporate any traces of damp and keep dry.

NT

[meow2222]

thats not a very satisfactory approach, and may or may not be adequate

In 99% of cases, reducing RH to stop the condensation. In the last 1%, salt contamination or rising damp.

NT

[Stuart Noble]

And how do you reduce RH other than by heat and ventilation?

[Maris]

In my previous house I used something called Limelite renovating plaster for the first metre of brickwork that is usually hard rendered by the damp proofing companies. It was lightweight and therefore there was no condensation. It was also non-hygrospcopic unlike Carlite. Sadly,the company don't seem to be around any more, although there are similar products on the market, I believe.

Maris

[Andrew Gabriel]

I have areas where the outside ground level is too high, and it's not realistic to drop it. I removed the damp plaster back to the brickwork. For scratch coat, I used 1:1:6 (cement:lime:sand) with a waterproofer additive. This can breath, but won't wick moisture through. For finish coat, I used regular gypsum finish coat, and it's stayed bone dry for years now, in spite of the brickwork behind still remaining slightly damp. Decorative finish must allow wall to breath though (e.g. matt emulsion paint or paper-based wallpaper).

[meow2222]

Limelite is cement based, and should be avoided in these situations. Whats needed is porous, so any damp can evaporate away. This means lime plaster.

very little, you've got tanking there really.

NT