Condensation in old stone house (Ed.)

[Citadelle]

Hello, I need some advice as to what to do about condensation due to high humidity.
We have a 600yr old building with granite and stone walls, granite stairs, they are all wet due to the rise in humid now, we have taken old wet wallpaper off, also some plaster, what should we do to stop this, thank you

 

[JohnD]

Improve ventilation

Find out where the water is coming from and remove the cause.

In UK the commonest cause is wet washing hung inside the house or draped over radiators.

Sometimes it is a steamy bathroom with no extractor

Sometimes it is a water leak from roof or plumbing, including hidden pipes under floors

Sometimes it is a wet wall due to guttering or brickwork defects.

Heat does not remove water, but it can evaporate it so that ventilation will remove the vapour. In your case water vapour will just condense on the stone walls, so you must remove it.

If you have plenty of money you can use dehumidifiers but they will not repair the cause.

Do not allow anyone who sells silicone injections into your house.

 

[Burnerman]

Try to reduce the ground level outside, if it's been built up over time, and Google French Drains.......they work very well.
John

 

[Citadelle]

We do have to reduce the ground level at the back of the old kitchen. Also, there is this grey stuff painted on the walls, about 2 or 3ft high, is this a waterproofing?
We have sorted the drain outside the tower wall, but as soon as the humidity rises, the granite steps have surface water on, we don't have any heating either yet, we try to keep the doors open during the day.

 

[Burnerman]

Clearly the water has been coming in big time, hence the crackpot idea of painting the first few feet of stonework.
For sure you'll need some help here but my first thought would be the floor, if stone flagged - probably without any type of DPC.
John

 

[Citadelle]

I was nearly crying today, thought I'd open all the doors and windows, big mistake, all the humidity came in, everything was wet, everything! Been trying to dry it out all day.
Went outside to the barn, which is attached to the tower. We sorted the downpipe out last year as it was split and water running down the wall. But when I looked today, the wall is totally wet, the barn roof is at an angel to the tower and the water runs straight off the roof and down the wall in the corner. They have infilled under the granite staircase, need to get a structural engineer to see if we can take the rubble out but worried it's supporting the stairs!

 

[Mike13]

I am guessing that the grey stuff is cement render, it may just move the moisture to where it is not meant to go.

go to https://www.thelimecentre.co.uk/ https://www.heritagecobandlime.com/lime-products and other similar sites to find out how the building was originally meant to be kept habitable.

 

[JohnD]

Photos of the defect causing rainwater to run down the wall will help.

It is presumably the gutter and/or roof at fault.

 

[Citadelle]

The grey stuff is like a kind of paint, if you try and paint over it the, the new paint peels off as your rolling it!

 

[Burnerman]

The paint is probably a rubberised coating, applied to try and prevent what is happening naturally - to no avail.
Don't allow any water to cascade down the wall, so attend to the roofing and guttering.......often French buildings have steep roofs which are sensible and are there for a reason!
Do consider french drains - they work well and the effect is seen after not too long.
I guess it depends on the size of the piggy bank, but reducing ground level outside is sensible, and floor excavation seems desirable too.
John