Can you actually get rid of damp??

C

claire32

Guest
Hi, just hoping to get some advice on a property my partner & I are considering buying.

It's c.125 years old and needs updating, has a new roof and double glazing but needs repair in a lot of areas. We have serious concerns re: damp. The sellers have a survey by an architect which indicates 'rising damp to rear of property' and to the front of the property on one side. Lateral moisture penetration particularly at rear wall and limited ingress at chimney breasts.

I have done some research, and there are issues which can be addressed to fix some problems like reducing the yard level at the rear which is much higher than it should be, replacing guttering, blocking up unused chimneys etc. ie looking at the cause of damp: [broken link removed]

Then there is the issue of insulating without perpetuating damp problems, which is how I came upon this info:
http://www.buildingscience.com/docu...ng-masonry-walls-in-cold-climates?full_view=1
but I don't know if any Irish company would know how to insulate solid masonry walls without restricting the walls ability to 'breathe'?? Anyone know of any company who does this as a speciality?

Has anyone ever completely eradicated damp in an old house by addressing the causes and using proper insulation?? Or if there is damp, is it a lost cause?

We really need to decide on this soon, and given that I already know about the damp, I'm not gonna get my own survey in case I don't want to buy anyway... Any advice really appreciated, thanks...

Claire
 
It depends if its ecomomical to put the money in to fix the dampness.

Why buy a building with problems in the first place?
 
Stay away from any old house with rising damp cheaply.

Damp on the floors can be fixed, but rising damp is a money pit.
 
You can stop it affecting you, the decoration and your bank balance. I assume the floor is all right. If not, dig out and lay a new slab as per good practice. The following day, while the concrete is still green, dig out 9"x1" deep channel all around. Following day remove infected timbers, hack off all affected plaster plus two feet extra. Rake out the joints. Give a double scud coat 1:1 sand/cement all around, wait for the first to set before applying second. Use a 2:1 sand/cement plus waterproofer mix for the first coat of plaster and try to get it reasonably level. Clean out the 9"x1" channel, moisten and plaster, just as the wall. Instead of using a conventional float for cutting in the angle, use something round like a small bottle. This will give a slightly bull-nosed finish. This is important so as the trowel doesn't cause a butt joint. Do not scratch the wall but when set give another scud coat 2.25:1 for adhesion. If the walls are really bad you may have to apply another coat of plaster. Make sure to scud between any extra coats. Apply the final 1/2" coat of 3:1 plus waterproof render. Clean out the 9"x1" channel, apply Ronofix and fill with the final coat mix. The plasterer has to be fully experienced in this type of work and the total thickness of plaster plus scuds will be about 1.25" deep at the highest point. Fix electric conduit and boxes onto render coat without puncturing it. This can be done with an epoxy resin. Drop the ground levels outside to at least 6" below the level of the floor. Again rake out, scud and plaster using 3:1 mix plus waterproofer. The final coat being 4:1. If necessary fit a plinth. Back inside again, STICK battens onto wall at 24" centres. Fix polystyrene slabs in between. Screw on the appropriate polyurathane insulation board. Skim. This method I've used successfully on several houses/cottages over the past 12 years. It does work. I wish you the best.
 
I've just read the heritage link that you gave above. Heritage aesthetics rarely come in to practical comfortable living. Let's face it, our real heritage was living in caves. Walls breathing, water passing in and out, Roman cement. Give me a break. People just want to live in nice comfy houses. Freezing in a 'beautiful' old house that has 11' - 14' ceilings and cold walls is not my cup of tea.
 

Yeah, not my cup of tea either... but worried about using modern insulation etc if the building wont work well with it. Thanks for your replies, esp such detail. I don't think the sellers are going to sell at a price that would justify buying and then doing so much work, so I think we'll steer clear and buy a comfy new house with insulation and solar panels )

Thanks for helping us make up our minds...
Claire
 
Hi claire32,
I know you have made up your mind but do not ever regret your decision.
When I was in my mid 20's we bought a similar house and I am a qualified tradesman(Not builder) but knew I could tackle a lot of work myself.
I spent 10 years fighting damp and ripping down walls again to try another solution.
Also they made it a heritage class building which led to a nightmare with what I could do with it.
The charm of an old house is appealing but I would not swap back from my insulated ,damp free house for anything.
Also with any old house(mine was 1896) there are always new problems cropping up to empty your pocket.
I wish you all the best in your new house.
 



Thanks Martin68,
I definitely feel more at ease about my decision now, as this would be my worst fear with buying the house!

So it's definitely a new house for me!

Thanks again for replies guys,

Claire
 


Capt. Beaky, I listened to several experts at Plan Expo 2009.
They deal with problems in lime mortar solid masonry construction.
I seem to recall they suggested that cement-based products seal it the damp.
Sealing the walls may see damp reappearing, and it may continue to affect the building fabric.
Have you followed up your work to gather some empirical evidence that it works over an extended period?

Your suggestion to lower the ground levels outside seems sound and may prove useful in fighting the rising damp.
Laying a new slab with a new DPM/Radon barrier/Collector box will deal effectively with any damp coming up through the floor.
A more sensible treatment for the walls however would be to hack off all the old plaster/render and allow them to thoroughly dry out.
Then apply some calcium silicate board: [broken link removed]
Too much insulation internally will keep the walls too cold: external insulation could also be considered but the whole building needs to be allowed to breathe.

Whatever is done, though, there is a long and costly road to follow to put things right.

FWIW

ONQ
 

Capt Beaky, given your experience, how much on average would this cost to do? Also, where are you based?
 
You need to solve the issue that is causing the damp first, Then when that is done it depends on how bad the damp is, ie if on plasterboard might be better replacing for eg if on a solid wall then you would maybe only have option to treat,
 
Hi ONQ. Just spent three days in a cottage in Co Kerry that I renovated about 12 years ago. Warm and damp free.
The damp may be trapped in the stone between the two layers of waterproof render but it does not affect the decoration or people living in the house. Remember, a concrete slab keeps the moisture under the membrane without ill effects to the hardcore, 2" down or sand! No tide marks, efflorescence, peeling paint or silver fish. Lots of granolas that seem to live permanently in heritage sites spin myths, both urban and rural, about the downside of modern buildings/workmanship. One of the reasons given for the increase in longevity is in the advancement of comfortable housing. Say no more.
alana said:
Capt Beaky, given your experience, how much on average would this cost to do? Also, where are you based?
Click to expand...
Hi alana. Hacking off both inside and out, preparing background, plastering and insulating as mentioned would cost in the region of €70psm. I've just had a look at old work sheets giving prices then and tried to relate them to today's prices. Living in Dublin but spiritual home is in Kerry
 

Aha, fair enough. This is good to know and thanks for the reply and for not taking offence. I've become a big fan of empirical research over the past few years because buildings don't always behave in the way we expect them to.

Just on the off chance, have you used any sand/lime products as insulation anywhere and, if so, what were the results?


I take it the by "granolas" you mean meusli-bar and cereal munching Greens with conservation agendas? I take your point.
However my point was that cement based products will tend to seal this moisture into construction that requires by its nature to breath it out. It stands to reason that cement-based products by their nature are not affected by it.


Can I also clarify that this €70PSM price refers to the area of the walls actually treated and not the average price in relation to the floor area?

Finally, are you still doing this work?
[apologies if Ive missed it if you said this earlier]

ONQ.
 
Back to basics. Modern houses have cavity walls (insulated) and a damp course. Old houses have stone/rock inner and outer wall with a rubble filling, and sometime use slate as a damp course, which can crack. Some people try to cover damp up with plastic, battens and lining the wall, this just puts off the problem. Sealing it in by any method leaves a cold wall, and damp will find its way out some other way.
Chemical injection could stop the rising damp but in my opinion is hit or miss on a rubble filled wall. They do give a 20 yr guarantee. Rendering the walls like "Cap.Beaky" say is essential. Hydroscopic salt is brought up from the ground into the plaster, this plaster must be removed.
Rising damp can rise several feet up the wall, If it reaches wood, the constant damp can turn to dry rot, which is very serious, you can smell this mould in a house.
Just to clarify, Black mould is not always an indication of rising damp, hydroscopic salt in the plaster is.
 
onq, in London during the 70s - 80s, lime render was used on top of s/c render which was applied on top of NEWTONITE in cellars, coal bunkers and basements. While it was good for dampproofing I'd say the thermal insulation was rather less. Lots of these places were being turned into restaurants, toilets and wine bars.
The price mentioned is approx per square metre.
I'm still involved in the building game. Mostly damp and insulation. And looking forward to retiring in 2014
The granolas are as you had anticipated
What really is problematic in this field is the amount of scientific data being tossed about. Get your damp, cold bridgeing and insulation sorted and you're there. Some granolas can talk 'til they're blue (green!) in the face about the incidentals but living in a nice warm house is what it's all about. The rest is scientific semantics.
 

Let's not run down the fact that at long last we are seeing some empirical data [such as your own anecdotal confirmation above] replacing old wives tales.

Unfortunately we're not seeing all of it - there is considerable evidence calling into question the whole Global warming scenario on which all this Greening of the Earth is being based. But that's for another thread.

ONQ.
 
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