Damp Wall

[Wingedharpy]

I think I probably know the answer to this but thought I'd see if anyone can give me advice.
We have an internal wall in our Victorian terraced house that has started to show signs of rising damp.
Several months ago,- maybe as long ago as 2 years, we got a damp-proofing firm in to look at it and advise and the guy said that he thought we had caught the problem early and that we would get away without the need to re-plaster the wall (just what I wanted to hear).
The firm then removed the skirting and injected the full length of the wall with some damp-proofing cream stuff in a trigger gun (after drilling holes in the wall obviously) and they replaced the skirting.
He said that the wall may take a long time to dry out and that we should be patient.
The wall is not showing signs of drying out. The problem is no worse but after heavy rain it is more noticable than if we have had a long dry spell.
Does my wall need replastered or could I get away with some sort of heavy duty covering eg. Wallrock thermal lining or wooden panelling?
Advice please.

The wall is probably contaminated with hydroscopic salts which are the reason the wall is permanently damp. If this is not the case the wall would have dried out. Stripping and replastering is the only long term answer.

Covering up the problem will only make things worse in the long term.

More worrying is the fact that the damp on an internal wall appears worse after rain - could indicate a broken drain?

I think you need to have a look at the cause of damp- injecting it may not have done anything. I'd second the broken drain theory.... Sorry op! Did the original tradesman suggest why it was damp at all?

You're scaring me now!!
The damp just looks like a dark stain which starts at the height of the skirting board and goes up approx 12 inches at it's highest. It has no odour and is not getting any higher or spreading out more width-wise - it doesn't stretch the full length of the room.
I can't think that it would be a broken drain as we have no drains on that side of the house - all drainage is on opposite, external wall which is perfectly dry (as are adjoining neighbours drains ie their drains are not situated against our damp wall ). When it first appeared we asked neighbours if they had a washing machine or a dishwasher against that wall but they assured us they didn't.
Original damp-proofing man didn't give any explanation as to what may have caused the damp other than in very old houses such as ours, the damp-course often consists of just a layer of slate and with shifting soil due to water, tree roots, earth tremours (which we have had 2 of in the 25 years we've lived here - and yes, we are in the UK) movement can cause this slate to crack and render the damp-course ineffective.
Is there any way that I could check my own drains? - or is this a stupid question?
Thank-you, by the way, for taking the time to respond - I truly appreciate it.

what's the floor made of? concrete or wood? Is it near the kitchen or a radiator - there may be a leaking pipe. If wood, have a look underneath.

Have a look at your incoming water main and decide if it is copper, steel or lead. It probably runs under the floor from where the forgotten buried stopcock is, next to where the front gate used to be, to where the kitchen sink used to be

if the floor is concrete, decide if it was original, or poured later to replace a rotten timber floor.

If the damp is on a party wall, the neighbours might or might not be aware of any leaks.

If the damp patch is semi-circular, the source is probably in the centre. It will be behind the skirting board as well, you just can't see it.

If you call in a damp-proofing company, you can rely on them to say you need damp-proofing.

And... if there are hydroscopic salts in the plaster, would these not attract more moisture anyway when it rains given that the atmosphere then would be wet?

The floor is concrete and I think, original. It is now covered with laminate flooring.
Neighbours are not aware of any leaks - it was the first thing we thought of given that in that room there is absolutely nothing on that wall - no radiator, drainage - nothing.
It's not a semi-circular damp patch but rather a long fairly uneven patch - almost like a graph with peaks and troughs but no regular pattern.
The incoming water main is at the front of the house, as is the stop-cock, and looks to be copper to me. There is absolutely no sign of damp anywhere near this.
The damp wall in question is at the rear of the house - it used to be the old coal-house, I believe but was extended many, many years ago before we moved here.
The kitchen is sited next door to this room but the drainage for the sink etc is all on the external wall which is the opposite wall to the one which is damp.
Who else would be good to have a look at this for us?
As you say, damp people would just say we needed more stuff injected or whatever and as we've already done this, and I wasn't really impressed with that company, I'm reluctant to go down that route again.

Somebody needs to look at that concrete floor, and probably dig it up. Start by removing the skirting to see if the pattern of damp gives any clues of the cause.

If you really have got an original Victorian Concrete floor (unlikely) then it will not have a DPM. However this would cause the whole floor to be damp, not just one section of adjoining wall. I think it's a leaking pipe. More water comes out of a leaking pipe because it is under pressure. Leaking drains tend to wash away the foundations and soil and make a big cavity going downwards. If it's bad enough, the house eventually falls into the cavity.

Plumbers and electricians just love people who have laminated floors that "can't" come up.

Well that's reassuring!!!
The whole floor is not original - just the first couple of feet of it from the kitchen (old coal house).
The rest of it is a modern extension so presumably has a dpc in that bit.
I'm off to get my spade and dig a hole!

Just a thought, but did the company which did the damp-proofing work provide you with a guarantee? If so, and the problem hasn't been fixed, you might be able to get them to come and sort it out at no further cost to you given they should have got it right in the first place

damp-proofing guarantees are fundamentally worthless. It will probably say that it will prevent rising damp coming up in that particular spot. They will say it must be hydroscopic salts in the plaster which you did not pay to have stripped off and re-rendered. Then they will say you must have a leaking pipe which is not covered. If all else fails they wil offer to repeat the same injection in the same place under their guarantee. And it didn't work the first time.

"... It's not a semi-circular damp patch but rather a long fairly uneven patch - almost like a graph with peaks and troughs but no regular pattern. ..."

From that description it sounds like classic rising damp.

If self-help fails then I suggest these (choose Chartered Building Surveyor option) are the experts but you would have to pay a fee for their advice.

Thanks very much Pendeen.
I used a Chartered Building Surveyor once before to look at some wall cracks for me and I found him to be excellent, even though he could not be specific about what caused the cracks.
Someone who knows what they're talking about but with no vested interest is what I need and it sounds as if this will fit the bill.
I too think it's rising damp as there are no pipes in the vicinity and, if it was a pipe which was still leaking, surely it would be getting worse?

@Wingedharpy

Did you find the cause, in the end?

Good Lord @PigletJohn, almost 10 years on and we've only very recently got to the bottom of this!
You were right - aren't you always?!
It was caused by a combination of seeping, sewer - benching in main manhole, badly erroded at the base and excess water sloshing around under rear of property.
This, in addition to some other discovered drain cracks, combined with non-breathable laminate flooring laid over original quarry floor tiles led to excess moisture in ground finding outlet up the wall.
Seeping sewer now fixed.
Other leaky drain work in hand.
Laminate flooring, as yet, still in place.
Damp patch, no better as yet, but no worse.

thanks!

@Wingedharpy - who finally diagnosed the issue?
I have a prospective purchase - Victorian end-terrace - with a 20cm high damp patch in small hallway on the party wall from the survey (surveyor said don't worry about it just move in and then investigate) and can't find who would be the trade to contact - spoken to a damp surveyor who said no point surveying whole house for a small area, and a stonemason who said you need to live in it to see if weather is affecting it eg rain through facade.
Seems crazy to proceed with no expert view, especially now I've read your story and PG's input. But who?

I mean PJ's input. Soz PigletJohn

@daisyfraser : It sort of came to light, eventually, due to further developing issues (ceiling and wall cracks) which were investigated via house insurance, to exclude subsidence.
No subsidence, thankfully, but drain inspection recommended by a building surveyor (I could have saved a fortune if I'd just lifted the manhole cover myself) led to all the dots joining up.
Can the people selling your potential property not cast any light on the matter?

Thanks for the swift response. You mean you could then see leaking when you lifted the cover? (for info if I go forward and will have to maintain the place)
Surveyor has looked at that though and says all good.
This is a good point - vendors were there when he surveyed, he has said nothing about their thoughts on it. He put it down to the Victorian DPC ie slate, moving over the last 130 years, but I find from other research this is perhaps not a 'watertight' reason.
I can put it to vendors via solicitor though. Thanks for that.