Riding damp - is it treatable?

[roobyred]

If you have had experience of rising damp, could you advise would you buy a property that has it?

A property has come up that needs revamped, but two of the rooms have rising damp along the exterior wall which has two blocked up chimneys. There's a quote of 4K to get it treated. I'm just wondering how successful these treatments are. The quote is to install a dry wall membrane and plaster over the wall. The survey notes that the existing damp proof membrane is bitumen.

The house has potential and is within budget but this damp aspect does not appeal.

There's a theory there's no such thing as rising damp. Are you sure it's not lack of ventilation due to the blocked chimneys?

www.heritage-house.org/damp-and-condensation/types-of-damp-what-have-i-got/what-is-rising-damp.html#google_vignette

Thanks. The report acknowledges that it could be the chimneys, so would you just drill vent holes in them to let the air circulate?

Unfortunate typo in the title!

Did a 'damp proofing' company quote you that? Treating the damp should be finding the cause, not just sticking some special membrane on to cover it up.

What's the ground like on the outside of the external wall? If the ground is too high or too close to the house it could be bridging the damp proof course. We've just bought a house with a damp.problem in the front corner, but someone previously poured concrete in the front yard and a path along the side of the house right up to the wall. Solution to dig out a channel and fill with gravel so that wet ground isn't right up against the house.

Your chimney could also be contributing but I think that would be penetrating damp rather than 'rising damp'

Also what were the readings and is it actually causing any issues and is it an old house? (I.e peeling or Blown plaster) Older single skin houses are susceptible to 'a bit of damp' especially on external walls. We had high Ish readings in our old house shown by the buyers survey, but they sent round a damp guy to investigate who said it was basically normal. It had never caused us any issues we didn't even know about it!

Long story short, if it was a great house, in budget that needed doing up anyway (so replastering wouldn't bother me) then it definitely wouldn't put me off. But make sure you find the source and fix that rather than just putting a barrier up.

@Dramallama91 unfortunately it's a flat, so the wall with the damp is accessed in the neighbouring property. I can't tell if the DPC has been bridged- how would you know?
That flat has had its garden landscaped so there is a flower bed running along the house wall and a path has been laid which is right against the house. Sounds like that could be causing the issues. They are old houses.

If it's a flat I would steer clear. Trying to get others to agree to (and possibly pay for) various works is a nightmare. Even just coordinating things that they don't have to pay for but might need access etc.
Damp is such a tricky issue and usually requires a few attempts to figure out what's causing it, never mind how to fix it. If you can't access various bits of the property easily (or have no control over what others do with their bits of the property) I think it will be very tricky to solve.
Don't get any chemical treatments though.
Your Old House UK - Repair and Conservation on Facebook has excellent (slightly cultish) advice. Maybe ask on there what they all think?
Just my thoughts!

Ah so when you said external you meant external to the flat rather than external to the building?

Just to be ultra clear, for the damp wall, the other side of it is someone else's flat rather than the outside of the building?

In which case I agree with PP unfortunately

No it's the outside of the building. The flat for sale is the lower flat. I live in a large city and don't have the luxury of affording a house, but this is a flat with garden so is appealing.

I would still be mindful of a flat with damp.
The cause of damp can be remote from the actual damp patch. If you don't own the whole building then you rely on other cooperating.
Having said that, all properties have some kind of issue and I'd rather a trivial patch of damp than a cladding issue!

You’ve mentioned membrane, bitumen, and finally lower flat.
Is the flat partially below the external ground level? Like a basement flat?

No it's a block of 4 flats. A ground level flat. The selling agent has included a quote for treating a damp problem which is along the south facing wall - the external side of that wall is in the upper flat's garden.

I've lived in flats for years and have no issue with arranging communal repairs. This would only be liaising with one other property, if the outcome is that their paving has bridged the DPM. But I don't want to invest in a property if damp is going to be an ongoing issue and am just wondering if others have treated rising damp successfully.

should be very easy to see if the ground level is too high and has bridged the DPC.
Does the RM advert even show it in the photos?
Is the building cavity or solid wall?

Sounds like the garden his higher than the damp course and has breached it

your relying on the neighbour to sort that it’s a risk

It's stone - about 100 years old.

Is it the level of the path on left that could be causing it? The right side is a flower bed.

So it appears like the dpc would be between the large course of stones and then the thinner layer, so about level with the base of that utilities box. Is the floor level in the ground floor flat level with that top step? Is it solid floors? And also, does the survey say if there is a cavity or not?
What exactly does the survey say about the dpc?
Anyway, chimneys. They are supposed to be capped/cowled and vented in each fireplace. That basically involves just knocking a hole through and putting a cover over it.
Coming to your question. I would not have complete faith that an injected dpc and the membrane will fix anything. In effect you are just hoping the damp doesn’t rise a meter up the wall.

Floor on ground flat is probably level with the third step. Floors are wooden suspended floorboards. There will be a small cavity underneath. Oddly, survey says nothing about damp but the agent has drawn attention to the supplementary report with recommended treatment. It says there's rising damp but notes the chimney stacks are not ventilated. The stacks are on either side of the stairs into the top flat.

So, you can probably confirm the height of the dpc by just having a close look and seeing if you can spot a some bitumen.
However it looks like the dpc and ground level are fine, and if the dpc is where I think it is, the floor joists sit on top of it. So if all of that is correct, we can probably dismiss the dpc as an issue. Also, the survey did not mention it.
Which leaves the unventilated chimneys. I can’t be sure, but they should be easy to ventilate. Usually the opening is bricked up with a single skin of bricks. You just get a vent put in towards the bottom. Just a bit of drilling and chiselling.
You need to look at the top. The rain should be prevented from entering. Usual methods are a ventilated cap or cowl, or even the pots are removed but an air brick is put in the stack. Is there a photo?
You could/should try and use the report to get the 4K off, but I don’t see ventilating the chimneys as a deal breaker. It would take months to gradually dry out though.

Thanks very much @HellsBalls
No photo of chimneys but sounds like an easier job to remedy.

Stand back and take a much wider pic of the damp wall. Indicate where the damp patch is. The picture needs to show all the drains, pipes and manhole covers, and one going all the way up to the roof and gutters, and any overflow pipes.

What is on the inside of the damp wall? Anything containing water, such as a kitchen, a bathroom or a radiator pipe?

If the damp is on the chimneybreasts, please photograph them.

In old houses that have had fireplaces bricked up, it is quite common for builders to have shovelled rubble into the hole to hide it and save them the effort of carrying it away. The rubble tends to hold damp, and to absorb it from under the hearth, which does not have a DPC.

Is the flat you are buying ground floor from your recent pic or is it a basement flat? And maybe ground level at the back of the property?

If it's ground floor and there is a suspended floor then the damp should be fixable with improved ventilation and/lor identifying the source of the damp. Below ground and it will involve tanking and drainage and all sorts and will be expensive.

It's only bedrooms on that side of the building - upper and lower flats. No downpipes which are all at front and back of the house and situated centrally. Radiators are more internal so doubt the pipes go close to that wall.

@PigletJohn

No evidence of extreme damp. Fireplaces completely bricked up. Signs of damp in one bedroom. But it has cavity wall insulation. Is that the issue?

Difficult to say. How old is it? And what type is it?
Is that the weather side of the house that gets the driving rain? And how is the condition of the pointing?

How old is the insulation? No detail about it. House is 100 years old.

No it's the south/south east facing side with damp.

Pointing looked ok.

So their solution is to hide it with a false wall that's dry enough to plaster?! Yeh, that'll help... not. Their "solution" won't address the cause or the resulting mould spores that will inevitably be in the air/building and will worsen the problem by reducing airflow.

No I wouldn't go anywhere near a property with rising damp. Maybe if it was very very cheap for what it is and I was able to live elsewhere until the issue was permanently fixed.