Damp At Back Of House - Expensive to Fix??

[MrHappyChap]

I recently had a look at a house which is for sale, and apparently there is damp at the back of the house.

I didn't actually notice it myself, the estate agent later told me on the phone that it had been mentioned in a survey which someone had done. The sale was agreed, but the sale fell through because of this.

The damp is in the kitchen extension which looks as if it was built in the '70's. The back garden consists of a very steep hill which I expect runs the rain down to the kitchen.

Does anyone know if getting this type of problem is difficult and/or expensive; and what work would usually have to be done to solve the problem?

[BillR]

There was a similar problem welsh house on the Property ladder TV program recently. They were told the back would have to be "tanked" to keep out the water, which they didn't have done. Later water started forcing itself up through the new floors in the rest of the downstairs rooms, after they had replastered! Basically the house had been built where a spring would be in wet weather. Struck me a situation to avoid at all costs.

[David W.E. Roberts]

Terrace, semi, or detached?

One solution could be to dig out at the back, and install drainage which carries water round the house and away at the front. Easier to do with a semi or detached than with a terrace!

Cheers Dave R

[MrHappyChap]

It's a terraced house, though there is a private alley-way at the side of the house which unfortunately belongs to the house next door.

[MrHappyChap]

Do you remember did it cost a lot to get the work done?

btw, what is meant by having the back "tanked"?

[Michael Mcneil]

It would be a straight forward job to get a JCB in there and clear it all for the terrace if they all agreed and if you could get a machine in there. I doubt that the others would want it done as they would have sorted it by now. Tanking or waterproofing just one part of the terrace wouldn't do the job.

My advice is walk away from it. You may find that it is one of those never ending jobs keeping it dry no matter what you do. You don't want to saddle yourself with that for the next 20 or 30 years do you?

The worst case scenario is that you fall out with all your neighbours, spend a fortune having a drain dug that has to channel through your house and spend a few thousand lining the walls with fibreglass or whatever, then find that it is coming in from your neighbours' houses too.

[N. Thornton]

First thing is to find out if you actually do have damp. Most damp surveys tell you almost nothing of any use.

Regards, NT

[BigWallop]

Tanked, is to have the outside or inside of the walls damped proofed by building it in like a water storage tank. In your example, the tanking method would be created most effectively on the outside of the walls. The earth would be dug out to just below the foundation and then a water proof material would literally be wrapped around the outside to form a skin. This skin would be around the depth from the bottom of the foundation works up to the third or fourth row of brickwork or at least 500 to 600 mm above ground level.

With the skin in place around the outside of the walls and soil back filled to its original level, any water in the soil is then forced to wrapped around the outside of the damp proofed skin and so isn't allowed to actually touch any porous stone or brick. This stops the dampness from rising up inside the material of the wall is made from.

The description above sounds rather an easy method of making the whole thing work, but it needs to done properly to make sure water isn't getting between the damp proofing skin and stone, so the damp proofing is best done with either chemical injection or spraying then a solid barrier coat placed on the top of it. Or it can be done with heavy bitumen coatings applied with thinners to allow the mixture to be absorbed on the first layers and then thicker layers applied over them to build up a barrier that is going to last in the conditions found in these types of site.

A good builder or damp proofing company would be able to sit down with you and explain the different methods which could be used in your situation.

[stuart noble]

has quite a lot of useful info about tanking. I think SBR has generally replaced bitumen for these applications.

[BigWallop]

"stuart noble" actually

Another great link for the ever growing favourites list. Thanks Stuart. :-))

[MrHappyChap]

So how would I know for certain? If I got a builder to come round to the house, do you think they would have a fair idea what is wrong and how serious (or not serious) any problem is?

Or would the extent of any "problem" only be known once someone dug the place up?

[Richard Faulkner]

In message , MrHappyChap writes

Apparently there is damp - I didnt notice it myself - it was mentioned in someone elses survey -

As a result of the above, a chunk of this forum is telling you that the house is suspect, will probably flood, and you shouldn't go near it.

Some of the forum is telling you that a surveyors damp comments dont mean a thing.

Have you seen the previous survey? If not, and you like the house, get your own survey and ask the surveyor to comment on the potential for flooding due to the steep garden. Also ask for details of experts who will be able to advise more specifically.

Then form your own opinion.

[MrHappyChap]

I suppose a good thing to do would be to have a look at the house 1 or

2 days after a very rainy day, and bring one of those gadgets for measuring dampness?

I'd guess this might give me some idea of the extent of any problem?

If I ask a builder to come out and have a look at the house with me, would they usually be prepared to do this even though I do not own the house, and there's always the possibility that at the end of the day I won't either...?

[BigWallop]

A damp meter is not really very reliable because it will say it is detecting dampness if it is pushed harder into the wall than is really needed. The best inspection is carried out with your eyes. If you can see wallpaper peeling or if it is as bad as having mould growing on the walls, then you know for sure there is a problem.

One test I was told about involves trying to stick a single ply of cheap toilet paper to the wall in various areas, especially near the bottom. If it soaks quickly, then the wall is near collapse. If it just sticks, then the wall is only damp. When the loo paper doesn't stick it is more than likely the wall is dry enough to live with.

[N. Thornton]

Hi. I'm inclined to think we dont have anything like the necessary information, I have the impression the OP doesn't either. A survey could be anything, from a charlatan with a damp meter to a proper structural survey with core samples taken to confrim diagnosis. Sitting here I have no clue, and dont see how one could advise you on this one, other than to say you need some proper reilable information to move forward with.

A minimal cost starting point would be to read up on all the signs of damp and go have a look.

Regards, NT

[stuart noble]

...and your nose. Get down and sniff. The smell of damp is pretty unmistakeable. The palm of your hand also. Find a good bit, then switch to the suspect bit. It'll feel cooler, clammier.