penetrating damp form neighbours house

[Spat]

I live in a victorian terrace on a steep hill, my neighbours house is about 2ft above mine and I have a damp problem (plaster falling off) on the party wall (from floor to about 2ft high!) where my wall is below their floor. Presumably it's their damp cellar below the DPC. Can anyone help with a diy solution or is this a professional job? I had thought about removing the plaster back to brickwork, putting in some kind of plastic membrane (glue onto the wall?) and plastering over the top. Is that possible or even sensible? Thanks for any advice

[Phil L]

no it's neither sensible nor possible - plaster won't stick to it. If you take the plaster off and drill holes in the brickwork level with your floor and inject it with DPC fluid, this will stop any rising damp coming up, but after you've done the inside brick, you'll have to drill right through the existing holes and inject the corresponding row of bricks on their side, this is assuming they won't let you into their cellar to do it from there, which they almost certainly won't.

The drill and the DPC fluid and pump are available from hire shops

Expect replies concerning the 'party wall act' and how you may be able to use it to your benefit etc, my only advice WRT this is that you will have damp walls for a long time yet as it will drag out for years if you decide to go down this road.

[Cash]

Presuming that the wall is of stone or a 9" or 13" brick wall, the only possible, permanent cure to this (if there really is one) is to inject the party wall with a chemical DPC *OR* tank the wall in the neighbours cellar

*OR* both [1] - as the method that you have suggested is unlikely to last.

---------------------

[1]

(A) If there really is a sizeable and useable cellar next door, then the problem is more likely to be rising damp due to a faulty or missing DPC rather than water penetrating through the wall (at or near the base of the party wall).

(B) Or if there is only a small 'void' between an earth floor and the floorboards of the next door property, then it could simply be a build up of rubbish or soil against their side of the party wall causing the problem - and simply removing this will be the cure.

(These are only guesses based on the information supplied).

Cash

[Spat]

Thanks for the replies. My neighbours are very reasonable so drilling from their side may be possible. The wall has a DPC of engineering bricks at floor level my side above a 1m void onto earth, Guess I go next door and see if earth has built up against the wall,clear it is necessary and then sort out injecting fluid into the brick wall if that doesn't cure it. Is a single horizontal line of injection holes ok (spaced correctly of course) or would the wall need to be injected vertically to their floor level too, covering the whole 2ft wide section? Prersumably they have a DPC at floor level. Thanks again for the advice.

[dave]

On Mon, 1 Dec 2008 14:54:36 -0800 (PST), Spat wrote: ...

Have had similar problems although out neibours are on the same level. Our party wall is in fact two thicknesses of brick with no cavity. (No idea if that is usually the case). What I can tell you with certainty (much detail omitted here) is that the damp in this case is rising

*through the mortar* itself and absolutely *not* through the eng. blue brick layers. Problem is, neigborgh is elderly lady and not interested in sorting this out. It will have to be fixed from both sides obviously as the two vertical layers of brick are in contact with each other. Having said that I knocked out a test section some 3 bricks long, replaced the mortar with appropriate additives and there's no sign of damp in that area now.

Good luck fixing your house.

[BigWallop]

Just a thought, but have to ask. Is the damp spot on your wall anywhere near where the neighbours bathroom would be? I have known a bath or shower seal to leak without being noticed, and causing a damp patch to form on the next door neighbours wall.

My brothers house was a middle terrace, with each house on a different level. His neighbour's bathroom was on the ground floor and the bath was against the party wall. The sealant around the bath had cracked and opened slightly, but opened more with the weight of someone using it.

The dribbling water through the gap in the seal kept attacking the wall and wasn't being allowed to fully dry out between uses. It eventually showed through into brothers house, as a damp patch from the floor to the height of the bath on the other side of the party wall.

Just a thought, but thought it might be worth you looking into.

[chudford]

I used Dryzone on my son's victorian house and it worked really well. You can see a distinct line on the brickwork above the injected line which is now completely dry, before the treatment the wall, on the north side, was very damp. It is very easy to use and the whole house only took about 2 hours to complete.

[Steve Firth]

It's both possible and sensible, but needs to be undertaken as part of a programme of eliminating damp. The plastic membrane is designed to have an air pocket for circulation of damp and it has a plastic mesh on the outer side which is plastered over. It needs to be installed and plastered by a professional since it's really not a DIY job.

However the first step in damp-proofing should be to eliminate the source of the damp and that probably means having a word with the neighbour to see if the source of the problem can be identified. It may be that debris has piled up bridging the DPC on their side, or that they have a leak flooding the cellar.

It's in both your interests to sort it out, so having a polite word, explaining the problem and starting from there is your best option. Their cellar may well need "tanking" and IMO the best way to do that is with Delta membrane products which are relatively cheap and are used to waterproof underground tunnels. They really do work but need careful installation and the provision of adequate drainage.

Start here:

the MD of the company has a holiday home near mine and has offered me advice in the past on waterproofing a room which had soil piled against the external wall. It has been extremely sucessful and the room has gone from (literally) dripping water to a dry useful bedroom.

[Steve Firth]

[The Real Doctor]

It's reasonable to assume that (a) this problem is less than a hundred years old and (b) the Victorians were not stupid. In other words, the original design must have prevented this happening, and it's some damage or alteration which is causing it now. So forget - for the moment - expensive elastoplast like tanking or silicone injections. Check both sides of the wall for whatever is wicking the water up (piled up rubbish and grot is my guess) and make sure that the underfloor spaces are properly ventilated.

Ian

[Phil L]

congratulations.

[Steve Firth]

Plastering over a plastic membrane applied to damp walls has been a recognised way of dealing with damp for at least a decade. You must enlighten me about where your revelatory insight that this is not possible came from sometime.

[Phil L]

He asked could he glue plastic to the bricks and plaster over this, when you find an adhesive that can hold a sheet of polythene + plaster + decorations etc to wet brickwork, please send details.

He could affix polythene to the wall, batten over and board and skim, but this too is asking for trouble, given that the screws will be into wet brickwork and will rust away in no time, not to mention the timber rotting and the damp not being cured, plus it's likely the whole wall would need to be done.

He was looking for a quick, and I assume, cheap fix, hence my advice WRT silicone injection for both sides of the wall, paying to have next door's cellar tanked is a bit OTT IMV.

[Steve Firth]

[snip]

He didn't say "polythene" he said plastic. He didn't state he wanted to glue the plastic to the wall he indicated, using a question mark, that he wanted an answer and was guessing that glue may be one way to do this. He made no mention of "decorations".

It would be stupid "solution" but he didn't ask for that as a solution either.

Silicone may help, but in my experience it rarely does anything worthwhile. Tracking down the source of the damp is the best idea, mucking about with silicone usually make things worse. If the neighbour won't play along and work to a fix that is to the benefit of both parties then going solo and tanking the wall in question is a possibility. This is, IMO, best done by applying a plastic drainage/ventilation/vapour barrier to the wall and plastering over the barrier. The barrier is attached to the wall using plastic clips, not glue.

[ConfusedCarbuyer]

Determine if it is lateral penetration of damp or rising damp. (by going next door and taking levels and drawing a section for both sides)

2 If it is all 150 mm above ground level on both sides (ie they have a cellar or void below your bottom timber floor level - unless it is solid) you have a rising damp problem and need a damp-proof course to be inserted chemically into the MORTAR of the brick such that there is a miniumum of 150mm between the lowest of the floors (your side) and the ground 3 remove all plaster that it contaminated with hygroscopic salts on both sides of the wall (likely to be 300mm to 1.5 m max if at all) Determine if it is hygroscopic by drying it out with a dry air electric heater (not gas) and see if it comes back at times of high humidity (not a fool proof method and only good over time) or test for contaminant salts (chlorides and nitrates etc with a bog standard chemistry set) If no contaminant salts just allow to dry over a couple of years 4 If salts present such as to make plaster unusable remove it 5 rake out mortar joints 20 mm 6 render with 3:1 sand cement with additive 7 If lateral penetration is found due to high ground levels next door then install dpc (Safeguard Dryzone recd) 150 mm above NEXT DOOR ground level and Tanking render your side using Sika No 1 to what ever height needed and to spec

Chris

[Phil L]

Which is why I said it's not possible, gluing something to wet brickwork isn't possible, to which you replied 'complete c*ck'

And it's unlikely that he is intending leaving it bare plaster.

He didn't ask for anything as a solution, he asked for suggestions

even though it's the cheapest option and is usually guaranteed for 25 years?

he asked for a DIY solution

very tight ones...based on the wording of the OP, I offered clear, practical advice and above all a fairly cheap option.

Yes it would be nice if we could all have the best, and most expensive thing available, but the vast majority can't.

[ConfusedCarbuyer]

If you accept Newtonite lathing as such a membrane you can increase this to nearly 50 years! Chris

[stuart noble]

Proof I suppose that plaster will indeed stick to plastic, providing the plastic is rigid and isn't dead smooth. It certainly sticks to plastic buckets quite well

[Steve Firth]

No I replied "complete c*ck" to the statement that you made, not the "it's neither sensible nor possible - plaster won't stick to it."

No mention of glue in your response and as previously indicated the OP did not state that glueing was essential, required, they asked if it was the right thing to do.

You may want to put down that shovel and back away from the hole.