Dampness on internal walls - ground floor. Please help

[tanveerym]

I am buying a new property for which the offer has been accepted and it is currently going through the purchase process. Its a 1930's end terraced property. I have had a detailed structural survey done on the property which has highlighted dampness on most walls (less than a metre high). This includes the wall on the end terrace side and the shared wall. At some places the dampness reading is quite high. The property has wallpaper on most walls.
The surveyor says "Our general observations and the measurements taken with a moisture meter indicated that the damp-proof course is ineffective in many places and that damage to plaster and decorations is occurring as a result of this."
I called in a local professional damp proof expert (has been in the business 30 years) and this is what they say "From the pattern of the readings obtained, it would appear, the damp proof course is being bridged by internal plaster which has been taken to the floor behind the narrow skirting board, so to overcome the problem, remove the skirting boards, along with the bottom 75mm of wall plaster and fit 5" new skirting boards. For the chimney breast area their recommendation is to go to bare wall, apply SBR, dry flex salt membrane and replaster"

Questions:

• Based on your experiences, do you think this should do the job to avoid the dampness in the future? If yes, do i need to re-plaster as the plaster will have been salt contaminated by now?

• The company has quoted £2k (i think its way too high) for the above work. I can remove the skirting boards and remove 75mm of plasterboard myself (using sharp chisel and hammer or a specific power tool). Any recommendations here?

I would appreciate any help received. Thanks in advance.

[dewaltdisney]

I hate to pee on your bonfire but this is not the best way to be starting out with a purchase. Every house needs a degree of maintenance all the time you live there and this might just be decoration and small repairs over time. When you are looking to buy somewhere you do not want to take on remedial tasks, this is the responsibility of the vendor to sell a property that is basically sound and not just sell the problems on. Now you could get the vendor to reduce the house by the cost of repairs but I would suggest walking away.

This is a brave step when you have done a load of money on surveys and legal fees but this might be the tip of the iceberg with other issues looming. A problem like that described sounds more like a defective damp course and do you trust the damp guy? If you are adamant that this is the house for you then negotiate a £5k reduction. It is not just the skirting it is all the remedial decoration as well after the damp guy has hacked it about and there is no guarantee this will sort the problem.

Have a good think.

DWD

[yartin]

If I really like the house, I will get proper builders to quote for the whole work including decoration and guarantee and ask this amount to be deducted from the purchase price.
Good luck

[tanveerym]

Thank you both for your replies

I have managed to negotiate £2k off the property and have already negotiated a really good price overall. Unfortunately due to the spend on legal fees and survey now I am kinda stuck with it. The skirting boards are really tiny and there is no doubt that the plaster will be connecting to the floor. My biggest concern is when I asked the local damp professional if they would guarantee that it will resolve all future issues, his exact words were "I have been doing this for lots of years (20-30 years) and this is based on my experience. We cannot guarantee anything"

A lot of other people on forums have highlighted similar issues and usually the fix has been to get rid of the touching plaster board which acts as a bridge. I understand there maybe decoration and re-plastering work required.

[dewaltdisney]

It is your choice and I can understand that the costs of walking away are a heavy loss. At least you are focused on the damp issue but the reassurance of Mr Damp would not be enough for me, I think I would get another quote just as belt and braces. Okay, if it is the DPC is letting through this can be solved by injecting in the affected areas with a chemical barrier where there is a breach. I just think you should be assured that Mr Damp's diagnosis is a bit more than a 30 years experience deduction.

DWD

[sammy.se]

Sorry if I'm stating the obvious here. Have you personally checked the following:

1/ The outside ground level is 150mm below the DPC?
2/ Vent bricks are all clear and allowing air to flow?
3/ ALL guttering is sound, and water is not dripping onto the ground, or falling against the walls where damp is?
4/ Externally, there is no cement (or other) render that covers the wall, and reaches the ground?

The bridging thing... that would only be true if the plaster is down below the DPC. is that the case? Can you see the DPC? (might be slate or bitumen)

keen to hear answers to the above.

Also, was there an extension built on the property, with a solid (cement) floor by any chance? this can cause air flow under the ground floor to be hampered, or causes a cold bridge upon which condensation can form, making it's way up the walls internally.

[tanveerym]

Thanks for your reply Sammy

The outside ground level is 150mm below the DPC?
I can see that ground level is only a brick from the DPC so roughly about 700-800mm.

The ground floor is of solid construction/cement and does not need air vents which may cause the condensation as you suggest. If I was t install a PIV (positive Input Ventialtion) in the property, do you think it would help?

Guttering is sound and there are no issues.

[sammy.se]

Thanks Tanveerym.

1 brick, presumably you meant 70-80mm. That will result in rain splash back above the DPC. It sounds like something innocuous but it actually does cause water ingress. Can you lower the ground by another 70-80mm around the wall, i.e. dig a trench, is it the public road, therefore not much you can do about it?

I'm afraid PIV are definitely out of my knowledge and experience range, so I couldn't give advice on that. But I would double check where the DPC is being bridged as a first step, and see if that can all be removed so that you have clear gaps between what is below and above the DPC.

Hopefully the ground floor cement has not been built upon over the years by previous owners, and is now higher than the DPC. That sounds like it could be a problem, but again - I'm not personally encountered that, so maybe others can advise on this specific situation.

[tanveerym]

Sorry I did mean to say 70-80mm :)

I will have a look into lowering the ground. What I still dont understand is the high dampness on the wall that is shared with next door neighbours. I suppose this is caused either due to the bridging of the plaster with the concrete floor or the condensation allowing it to settle on colder surfaces. Any advice?

[dewaltdisney]

Well, I thought from the outset that it was the DPC breached in areas but your damp guy seems to think not? Looking a bit deeper, do neighbouring properties have suspended wooden floors on the ground floor? It could be in the past that the wooden floor was taken out (wood worm, wet rot?) and a solid floor installed. Now when the screed layer is done it is laid on a damp proof membrane that is run around the edges and trimmed at skirting level. If this has not been done properly you can get a leech of damp transferred from under the slab into the walls as it bridges the DPC. Okay this might be a bit extreme and I do not want to fuel paranoia but I wanted to show you how wide an area of causes can present the damp issues.

I would really recommend getting a second opinion as that slim skirting is a strange issue, why?

DWD