Damp

[mmcmahon]

I live in a flat, I've just removed the old plaster walls in the living room as I'm about to get the room skimmed and the walls were a bit crumbly. I can now see why, the wood holding them in place was rotten and soaking wet, the inside of the exterior walls is also wet (sandstone) before I replace the walls I obviously want to sort this. Any advice on what I should do? Is this a DIY job or do I need a pro?

Many thanks

 

[oilman]

First, beware the damp surveyor, their remit is to get your money into their bank account and if it happens to fix your problem thats a bonus. I've been caught!!

Second take care of your building, it will be worth it in the end to do it properly, so don't rush to effect a cure. You could try the forum here . I suggest this as your house sounds as though it must be quite old if the walls are sandstone. How old is it? I wonder if the lining was original or if it was put up to deal with the problem you have. Also where abouts in the country is it?

Modern plaster finishes do not like damp at all, and cannot survive it. Lime plaster copes much better, it sounds old fashioned, but don't dismiss it, it does very well in many buildings dating from at least the middle ages. It is possible to do the lime plaster yourself, but plastering is always a major job if you're not a plasterer.

The damp does need dealing with, but it might be adequate ventilation thats needed, if you can provide more information this will help.

 

[mmcmahon]

Thanks, I'm in Scotland (Paisley) and the flat in approx 100 years old.

 

[aussiemike]

a problem like this needs step by step answers to basic questions, eliminating guess work, so that the true cause of the dampness can be identified. 1) ground floor flat? 2) external or internal wall? 3) fireplace/chimney stack?. you need to determine if it is rising damp or horizontal damp- ingress from outside, finally if an external wall- check outside for any sign off leaking gutters, rainwater pipes,etc. the wall will have saturation evidence..
you may have to tank the wall if it is rising damp and the wall is of solid construction ( you dont live in a basement i assume?)

 

[aussiemike]

to add, you could hire test equipment and check yourself the extent of the water saturation, it sounds worse than condensation- for which ventilation would suffice. try a protometer - which checks damp levels in plaster,or a speedy test, by which you take core samples using a drill, of both the mortar and stone- a small measured quantity is mixed in the test flask with gunpowder. this gives off a gas, which under pressure within the flask, tells you via the meter reading on the flask- the water content in the sample. normally anything reading over 5% indicates definite physical damp-be it rising damp or ingress. ventilation alone will not solve it, you need to eliminate the root cause.

 

[oilman]

I'd agree with using the speedy test, but I've got a couple of protimeters, and I would be very sceptical using them for moisture measurements in plaster, as any salts can affect the readings significantly.