Old house- 'damp' patches on walls

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chabsey

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I'm attempting to fix / renovate an old farmhouse (about 100 - 150 yrs old) that has a mix of rubble/stone/brick walls. It's a typical old farmhouse like many others, no DPC in the walls. There's also minimal ventilation as none of the UPVC windows have vent slots in them.

Now, I'm getting quotes for fixing a problem with the walls in three rooms, two rooms on one end of the house and one at the other end, all exhibiting the same problem.

To give a bit of background, the house is now rarely used, it is a holiday home and so can easily go quite a few months with no one in it and with little to no heating on (storage heaters). It was renovated about 10 years ago, all worked well. However, the interior end walls started showing signs of dampness pretty quickly, although it progressed to a point and didn't get any worse. It has never smelled of damp and there was no mould present on these walls.

The patches are light brown in colour and are concentrated in the areas where the chimney stack is. From reading online these correspond to stains caused by hygroscopic salts present as a result of years of fossil fuel burning, it appears to be quite common.

We've recently removed the plaster from one wall as you can see from the pictures it looks slightly damp-ish but not mouldy, not smelling of damp, but I'm not a damp expert.

The photos are of the upstairs bedroom.

My issue is with getting a builder who knows how to deal with this stuff. I'm fairly convinced it's not caused by water ingress, but rather by lack of heating, lack of ventilation and long periods of no-one using the house. The rooms get damp, the water is drawn to these salts and gets drawn out through the plaster in spots.

We've had builders contend that it's rising damp, (this photo is the second floor, and while it's the same on the ground floor it's not marked near the bottom of the wall) or just be generally vague.

It's frustrating as we've discovered what we know about these salts after a few hours reading on line, it's not hard to find this info and it's annoying that we can't seem to get a straight answer from any builders.

I'm loathe to spend a fortune on some supposed cure when all that might be required is something more basic.

We are in the process of putting in central heating (previously only has storage heaters) and hopefully going to get someone to live there full time which will help hugely.

The question is though, is anyone familiar with this type of damp on these kinds of walls, and if so what should we do to fix it and not have it re-occur in a year of re-plastering.


UPDATE - I can't post the pictures as apparently I've not posted enough topics! Anyone know how I can add a photo?
 
chabsey said:
UPDATE - I can't post the pictures as apparently I've not posted enough topics! Anyone know how I can add a photo?
Click to expand...

AAM doesn't support uploading photos. Upload them to an online service such as picasa and link to them there.
 
Ah right, if you want, PM me the links and I'll add them to your post. Posting links is disabled for new members to stop the spammers.
 
Damp

Hi Chabsey,

There are many issues that can cause moisture within the building. A site survey by a chartered builder or experienced restoration/renovation building company or architect should be carried out first before any heating system is fitted or works carried out. There are people who have experience with these buildings and there are many techniques for retro-fitting pre-1900 stone buildings. There are many builders in Ireland who will claim they know how to fix the problem. But due to a lot of bad regulation in Ireland anybody can be a builder.
A survey could save you a lot of money for now and the future. Your house if the work is carried out correctly should have no moisture issues.
 
chabsey where in the country are you, and maybe we can get some recommendations to you. as the poster above suggests its relavitively straight forward for an arch or surveyor to offer an opinion and remedial options
 
Dry lining over damp walls.

I'm getting quotes for the renovation of an old property that has bad damp in the walls. I'm putting in central heating and have previously had chemical injection to stop rising damp although to be honest chemical injection in old stone rubble walls is questionable in its efficacy.

Anyway, the walls are pretty damp still from the top down, I'm looking into possibly replacing the roof barges as they might be cracked. I'm also getting the attic vented as it's not currently and there's very high levels of condensation up there (dripping down off the old bitumen felt).

So, all that considered what I'm thinking of getting done is putting two vents in each wall (these are gable walls) that has the damp problem. Dry lining with insulation over each using PT timber for the frame and attaching in a few places with blocks backed with a plastic layer between the block and the wall. The vents would then essentially be venting this cavity between the insulated wall and the damp wall. I'd also add vent tiles to the roof and possibly replace the barges.

Would also be adding trickle vents in the upvc windows, using the house more (previously it would go months without any use, and with no heat on) and insulating the floor by digging it up, hardcore base put down and a new DPC put in.

The main area of concern is that the proposed solution of dry lining the damp wall (albeit with plenty of venting) is a problem waiting to happen.

What do people think? I'm essentially hiding the problem initially *but* I am treating it by venting and the wall and then hopefully finding out how the walls are getting damp from above and treating that as well.

Viable solution or madness?
 
Hi

Have updated this with the proposed solution a builder has provided me with. Please see the thread called 'Dry lining over damp walls'. Might make more sense to merge them both but I couldn't get the site to do that, presumably it's a moderator-only function.
 
lowCO2design said:
chabsey where in the country are you, and maybe we can get some recommendations to you. as the poster above suggests its relavitively straight forward for an arch or surveyor to offer an opinion and remedial options
Click to expand...

Based in Dublin but the house is in Wexford. I'm trying to find a list of registered / recommended heritage surveyors in Wexford and am not getting anything.

Any idea of the cost of one of these surveys? It's a 3 bed old farmhouse, nothing huge, not a listed building or anything.
 
There are other on here far more qualified than I to comment, but I believe covering up a damp problem can only lead to disaster down the line.

chabsey said:
Might make more sense to merge them both but I couldn't get the site to do that, presumably it's a moderator-only function.
Click to expand...

Done.
 
Hi chabsey,

About 3 years ago, I installed internal insulation in my own house (a 3 bed semi with cavity block).

There was no problem with damp as you have, but I was aware that one potential problem was warm humid air seeping into the area behind the internal insulation and causing interstitial condensation and other attendant problems.

In order to reduce this risk, I came up with exactly the same solution as you - ie to mount the internal insulation on treated battens and vent the resulting cavity.

I pressed ahead with the job and in hindsight I think that venting the cavity past obstacles like floors and windows is not a practical proposal. You might get some venting but you will also get significant dead spots on the wall and for sure at the window/door reveals. You will also have to consider fire issues and make sure that mice and the like do not get access to the cavity area.

In my case, I abandoned efforts to vent the cavity. The internal insulation has worked well for me but I put this down to very very meticulous attention to sealing the vapour barrier on the warm side of the insulation.

I would suggest that you do not do any internal insulation until you have found the source of any dampness and addressed it.

It sounds like your walls are solid masonry walls. I would seriously look at external insulation for such a case and it may sort out your damp problems at the same time.

If your walls are big thick traditional 2 ft walls, you might find that most of your heat loss is through other avenues like windows and chimneys etc. Maybe the walls should not be top of your hit list.

Also, maybe live in the house with a reasonable amount of heating for a while to see if the damp problem is just due to lack of use before you assume the problem is a leak.

Regards,

3CC
 
3CC said:
Hi chabsey,

...
In my case, I abandoned efforts to vent the cavity. The internal insulation has worked well for me but I put this down to very very meticulous attention to sealing the vapour barrier on the warm side of the insulation.
...
Click to expand...

The walls are indeed those 2-3ft thick type you mention, old style stone walls. Just to get this straight as you sound like you'd had a very similar issue, are you happy with the solution or have you had problems?

In terms of the venting they would presumably be (builder will put them in) vents quite high up and outside they would be covered with a plastic or metal louvre which would stop mice getting in I'd hope.

Also, you mention very meticulous detail in sealing the vapour barrier - I'm not sure the builder has mentioned a vapour barrier at all. As far as I know he talked of doing what I describe above and then plastering over the drylined walls. Did you add an extra vapour barrier?

Unfortunately living in the property for any length of time isn't an option as it's primarily a holiday home although that may change.
 
My situation was different in that the wall was constructed of cavity blocks (about 200m overall wall thickness). And I am happy with the outcome.

Just to be clear on the ventilation issue, in my post I was referring to ventilation of the cavity between the existing wall and the proposed internal insulation. I think you are talking about installing vents to ventilate the rooms within the house which is also important but a different issue.

I have no experience of old masonry walls but in researching my own situation, I did come across some information that may be useful.

As far as I can recall, the structure of masonry walls tends to degrade with time if they are damp. Modern blockwork walls are much more resistant to being damp due to improved mortars etc. Without internal insulation, heating in the house has a drying effect on the walls but internal insulation removes this effect. For this reason, if internal insulation were used on a masonry wall, moisture would tend to ingress from the outside without any heat from the inside to counteract it and dampness would probably increase. For this reason, I would not use internal insulation in your situation.

External insulation would have opposite effect, would heat up and dry out the walls and so may be preferable.

The u value of a 2 foot wall is not that bad so you might be better to look at other sources of heat loss first as I said above.

In conclusion, if your aim is to make the house more efficient, I suggest looking at the other sources of heat loss first and then look at external insulation if there is still an issue. However, if your aim is to prevent dampness forming while the house is not in use for long periods in winter - I am not aware of a solution. I suspect there isn't one other than to leave some nominal heating on.
 
chabsey said:
The walls are indeed those 2-3ft thick type you mention, old style stone walls. Just to get this straight as you sound like you'd had a very similar issue, are you happy with the solution or have you had problems?

In terms of the venting they would presumably be (builder will put them in) vents quite high up and outside they would be covered with a plastic or metal louvre which would stop mice getting in I'd hope.

Also, you mention very meticulous detail in sealing the vapour barrier - I'm not sure the builder has mentioned a vapour barrier at all. As far as I know he talked of doing what I describe above and then plastering over the drylined walls. Did you add an extra vapour barrier?

Unfortunately living in the property for any length of time isn't an option as it's primarily a holiday home although that may change.
Click to expand...
id question whether your house is suitable for drylining. could you call in an experienced architect used to dealing with old buildings or at least get a specialist contractor to assess the walls and construction before going ahead.

the old builders company springs to mind as a contractor worth having a chat with (NO connection), did you tell us where in the country you are in? and maybe more specific help can be offered

I dont agree with dry-lining old buildings and venting the cavity seems retarded to me.

have you considered hemplime insulation?
is your attic vented?
have you considered demand control mechanical extract ventilation DCMEV to deal with internally generated condensation?
have you dug a trench around the house to ensure water can exit the footings?
 
chabsey said:
Based in Dublin but the house is in Wexford. I'm trying to find a list of registered / recommended heritage surveyors in Wexford and am not getting anything.

Any idea of the cost of one of these surveys? It's a 3 bed old farmhouse, nothing huge, not a listed building or anything.
Click to expand...
only saw this now

[broken link removed]

my preferred method is hemplime followed by one those calcium type boards at a push, but get an on-site opinion,all dampness should be solved first!.
 
I have a problem with rising damp in an old apartment building, built in 1962, in a warm climate.
Each year we scrape off the plaster, which rises about 6" up the wall and redecorate, the problem keeps coming back.
I am having some renovations done on the apartment shortly and the builders have said they will remove the plaster as much as is reasonably possible under walls and put in damp proof course.
They said this will improve the problem for a few years but it will come back again. They are removing the tiles throughout the apartment which will allow some access to the problem.
I have been told I should ask them to use Tanking and get this put up walls about 1' and 1.5m up shower enclosure.
I would welcome any advice. Browtal
 
browtal,
- i assume that your apartment is on the ground floor of the block?
- are you sure the water isn't coming from leaks from bathrooms of an adjoining apartment?
- tanking will stop the damp from reaching the interior of the property, but it will not get rid of the water, a properly fitted damp proof should work for a long time and will stop the water at source.
- a shower room should be tanked or water resistant concrete/plaster applied to the walls to contain the water in this area and make sure it ends up in the drains where it belongs.

www.studioplustwo.com
 
browtal said:
I have a problem with rising damp in an old apartment building, built in 1962, in a warm climate.
Click to expand...
where you living?

what is the external ground level relative to the internal?

where are the water/ waste pipes near this wall? have they ever been surveyed?
 
Hi Threebedsemi and lowC02design,
many thanks for taking the time to help. The damp is on adjoining walls to next apartment and one outside wall.
I think you may have hit the nail on the head, the piping is old probably gun-barrell, giving its age. I think I should replace the piping when the floor is up. There is also damp on a dividing wall between bedroom and living room - which is not near the pipe area, can you suggest a solution to this. Perhaps water is escaping under ground and spreading.
If you have any further suggestions I would be most grateful.
Regards Browtal
 
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