Penetrating damp - how to dry it out

[zunetunes]

Been in this house in West Cumbria for 3 months its mid victorian, detached, part used to be the village shop, has a "barn" on the back. The majority of walls are about 18" thick and I think rubble filled. They are rendered and painted.

The house was in very poor condition up till 3 years ago. The then owner did a lot if superficial stuff to make it look nice but failed to deal with some fundamentals like penetrating damp! This is severe. Have taken the paint finish off the fairly modern plaster coating in the downstairs shop area and it's very damp. The whole house smells dampGetting the guttering and downpipes dealt with - a source but possibly not the only source of problems. Some exterior plaster/render is cracked and has blown. Am getting a local builder to do a patch repair.

So that's the background, now the question.
Once the gutters/downpipes/flashings are dealt with and the exterior effectively sealed to new incoming damp, how will the damp get out of the wall? Interior walls are either painted with modern paint or dry lined with plasterboard. Any further advice appreciated.

 

[Nemesis]

Well if the walls are sealed, it won't!

I presume that the walls are cement rendered, and painted with a modern paint?

The poor building is probably being suffocated.

http://www.spab.org.uk/publications_Q&A_renders.html

 

[Penners]

The cracked exterior rendering sounds like the clue to the dampness - assuming that the rendering is cement and not lime. The damp is getting in through the cracks and the cement is preventing it from getting out again.

The ideal solution would be to strip off all the cement rendering. The decision whether to re-render or leave the stone unrendered would depend on what you find under the rendering. However, assuming you do need to re-render, then this should be done with lime and painted with limewash. The building will then be able to give off its damp.

Again ideally - it would be a good plan to get the cement rendering off in spring/early summer, and leave the bare stone unrendered for as long as possible in the warm weather, but re-render well before winter. This will accelerate the drying out process.

Needless to say, you also need to be looking at all other possible sources of damp - dodgy gutters, poor flashing, leaks, and so on.

Of course, all this is the ideal. You may not be in a position to carry out such radical surgery to the building. In which case I think your only solution is to make good the cracked external rendering, do all the other checks and repairs mentioned above, and then try to dry out the inner skin of the walls as best you can (you should do this regardless of whether you strip the exterior). This would best be done by hacking off the gypsum plaster and leaving the walls unplastered for a few months, while heating and ventilating the interior, or in warm summer weather, leaving all doors and windows open. You could use a dehumidifier to accelerate the process - I know others on this forum have recommended this - I have no experience of it.

Once the interior walls have dried out, replaster them with lime and paint with a breathable paint (see lots of other past threads on this).

You might also like to use the link on Nemesis's thread called "Lime" to read some very useful information provided by the Lime Centre.

 

[middi]

Nemesis is right, when these walls were originally bulit, usually with lots of lime mortar and reasonably well pointed between the joints, much of the surface rain water ran straight off with a small amount penetrating the walls which was just as quickly expelled by evaporation and good ventilation.

Homo sapiens MK II came along and decided to cover the whole lot up with mostly non breatheable materials coupled with less air circulation suffocating the poor things to death, any water finding its way through cracks, joints etc... will have difficulty in evaporating and gets trapped for longer than normal behind these " hard renders" or unbreatheable coverings. And that includes most modern paints.

It has proved that if we wish to destroy the "breathing" balance of the original construction, we either do the job properly by allowing no water at all to penetrate the walls from iside or out and enclosing it in a lead coffing, or revert to repairs in the manner which it was originally constructed.

The problem which you are decribing can only be evaluated by a close inpection by someone that really understands these buildings and decide what is the best course of action to take.

Gervase may have a few well learned comments to make on this subject, amongst other contributers on this site of course.

 

[Nemesis]

It is very wet in West Cumbria.

I assume the building is stone, not clay?

I suspect the barn at the back was partly for the horse and cart for deliveries, with storage space above? Sounds very interesting!

This is Bog Farm Aldoth - and although it looked as though it was stone with brick additions, removal of a sheltering outer building revealed an older core of clay dabbin - which collapsed. It had been extended upwards with stone.

Somebuildings are older in pats than they seem at firts.

Poor old Bog Farm - I took this pic for the SAVE Buildings at Risk Register. It's listed grade II. There were plans to 'develop' but they were rather inappropriate - must find out what happened to it.

 

[middi]

Penners advise is exellent.

 

[Nemesis]

http://www.spab.org.uk/publications_Q&A_rain_penetration.html

Another useful piece of reading.

 

[Penners]

This is Bog Farm Aldoth

You certainly know how to give places charming names oop there!

 

[Nemesis]

Descriptive though!

May be a ggod place to point out

Traditional Buildings of Cumbria

by
Prof. R.W Brunskill

Cassell


Brilliant!

This little gem is also in Cumbria - I took the picture last year, and according to the CO there were plans for rescue.

I'm scared to go back in case it's the uPVC window sort of rescue...

 

[zunetunes]

Thanks for replies so far. The house is surrounded on all sides by roads so any building work requiring scaffolding requires roads to be shut off etc. As a detached 3 story buiding the scaffolding costs are quite high. To scaffold, hack off, leave for a few months then re-scaffold would be less than desirable. To seal the outside and then hack off inside plaster to let the walls dry out from the inside also sounds less than desirable. I'm in a quandry!

Here are some exterior pics http://www.coolblue.org.uk/GreatBroughton.htm

 

[Moo]

I see what you mean (and I know what you mean about scaffolding - we're in exactly the same situation, and it don't come cheap) !!

However, would it be possible to do some of it yourself, with the aid of a hired scaffold platform, at the back where the barn is? At least one wall of the house seems to be a possibility, and might give you a clue about what you're dealing with.

 

[bournonite]

I will probably be jumped upon from a great height here - but the solution we have found works brilliantly in this situation is to steel frame the interior walls - hack off plaster, and frame with 50mm steel studding - insulation batts go in betrween the studs, and plasterboard on that. It lets the walls breathe as there is then an air gap between the outer wall and the plasterboard, and you have not in any way changed or altered the original structure of the building. Its totally non-invasive. At the same time, the steel stud allows you to run any new wiring, pipes etc you need, so you get the benefits of modern insulation with the ability to let the building dry out and breathe. This lets you leave the outer layers as they are - dont even bother with the render - the wall breathes through the inside. Its not ideal, but its better than having to hack render and damage the outside walls in the process.,,,

I'll await the howls of outrage....

Pete

 

[Nemesis]

Not to be contemplated if you have original lime plaster, or indeed if you like a bit of original character to be left really. Can be very difficult where architraves and cornices are involved.

May be used in cases of real damp instead of the even worse tanking along with breathable membrane but...

 

[bournonite]

I knew there'd be a growl - but I agree your comments - most of the places we have used it have no cornices, and most times the lime plaster is falling off anyway... I did say it was a partial solution, and I agree you end up with less character - but some people actually want to be warm and dry!

 

[NT]

I'm not a scaffolder, but have occasionally seen scaffolding with the bottom floor of the scaffolding missing, which would probably be workable on a 3 storey with roads. I gather scaff can be supported on poles to the ground right next to the building only, or with more difficulty supported entirely off the bulding higher up.

The key may well be partial render removal, ie just to pull off what comes off easily quickly, and lime patch it if necessary. The plus is you only need a very short work window, eg working off the top of a truck or van parked outside overnight, using non-power tools.


NT

 

[zunetunes]

So is it okay to have a wall part cement rendered and part lime rendered?

 

[Gervase]

So is it okay to have a wall part cement rendered and part lime rendered?

It's not ideal, but any lime render's better than none. The less cement the better, however.
As far as scaffolding goes, you may find it cheaper to use a cherry-picker. Scaff costs for two erections on a blooming great pile like that would be in the region of £3k and above, and you could probably pick up a tatty but safe towable cherry-picker with 24-foot lift for less than half that. And at the end of the job you can sell it.