Damp walls but only when it's sunny !!

[owentaylor]

Did someone mention dry lining ?? there should be no plasterboard in whatever shape or form on the ground floor of a property this old.

Why is this?
Are you saying that in a property this old that damp is unavoidable?

 

[mac391]

No, not at all,,
Theres lots of reasons why an old house either suffers with damp or gets away with it. Not every old property has damp problems. I was pointing out that quick fixes such as dot n dab plasterboard can exaggerate damp problems and restoring it in a more traditional manner will probably work better.

 

[wwwebber]

The house has solid walls and solid floors so the lifting of floorboards etc is not possible. The interior of all external walls have been insulated / vapour checked with 50mm Gyproc Thermaline Plus to help with insulation & energy saving. All of the old plaster was removed due to it's age & condition. There was also alot of damage from salts which was a result of previous / current damp problems.

I'm leaning towards the cause being residual damp being retained in the walls from when the house was cold and very damp (those plasterers make a hell of a watery mess !!) or the high ground levels outside or finally it could be down to summer condensation.

It could be a combination of them all as the moisture has to come from somewhere to create condensation and I'm hoping it is coming from the already damp walls in conjunction with high ground levels and that when I've lowered the ground level outside and then filled with gravel that the moisture will gradually disappear.

Just to make things clear - it has been raining for the last few days, we haven't had any heating on and it's been quite cool inside - at no point have I seen any condensation or damp patches internally or behind the vapour check whatsoever. I will however be keeping a very close eye on things if we have another hot spell.

 

[JohnD]

how do you feel about increasing the ventilation now?

 

[wwwebber]

how do you feel about increasing the ventilation now?

I think most if not all of the moisture originates from the wall itself. The room now has no exposure to the wall except a 1cm gap at the bottom which will be covered by underlay and carpet anyway. And as such I don't see any point increasing ventilation to the room.

 

[mac391]

http://www.british-gypsum.com/pdf/PDS-022-01 Gyproc ThermaLine PLUS.pdf

Above is the pdf file on Gyproc thermaline plus. You say you have "vapour checked" your walls with it when in fact it sounds like you have just "isolated" the damp problem which the pdf file says "you must not do" There's also some scant info on not installing it whilst you have condensation issues.

You can download the "white book" with more info from the Gyproc website.

From what i understand, this is just a thermal insulation board and has no "anti-damp properties.
Have the installers fitted a seperate membrane at all ? And how was the gyproc installed ...?

P.S You definately need ventilation !!!! and no further work should be carried out until you have altered the high ground.....

 

[wwwebber]

http://www.british-gypsum.com/pdf/PDS-022-01%20Gyproc%20ThermaLine%20PLUS.pdf

Above is the pdf file on Gyproc thermaline plus. You say you have "vapour checked" your walls with it when in fact it sounds like you have just "isolated" the damp problem which the pdf file says "you must not do" There's also some scant info on not installing it whilst you have condensation issues.

You can download the "white book" with more info from the Gyproc website.

From what i understand, this is just a thermal insulation board and has no "anti-damp properties.
Have the installers fitted a seperate membrane at all ? And how was the gyproc installed ...?

P.S You definately need ventilation !!!! and no further work should be carried out until you have altered the high ground.....

Well, the boards are up now throughout the entire house using dob and dab straight onto the walls with no other liner as the vapour check is built in. The whole house was damp whilst they were doing this as it was winter , there was no heating and plastering by nature is wet and creates lots of humidity. I'm hoping that by lowering the ground outside the walls will dry out naturally and thus prevent any further condensation - summer or otherwise.

Thanks for the info - I'll read through it.

 

[wwwebber]

P.S You definately need ventilation !!!! and no further work should be carried out until you have altered the high ground.....

I suppose I could do with ventilating the small gap between the wall and the thermaline plus as this is where the condensation occurrs but this will compromise the thermal advantages. I also dont get any condensation at all in the actual room - unless of course you are suggesting that the condensation between wall and board originates from the room itself ?? - so can moisture from the room cause this much condensation via such a small gap ?. Please remember that it's been very cool & wet outside lately , I havent had the heating on and I havent seen any issues as a result.

 

[mointainwalker]

@mac391

re"Thermaline plus". Not sure what you understand by anti-damp properties but polystyrene is considered impervious to moisture under normal circumstances.

I recall reading research that stated that after 30 days total immersion in water , an expanded polystyrene panel had absorbed 0.2% of its total weight of water.

Ssound pretty good to me on the damp-proof front. Only weak point being the joins.

 

[mac391]

@mac391

re"Thermaline plus". Not sure what you understand by anti-damp properties but polystyrene is considered impervious to moisture under normal circumstances.

I recall reading research that stated that after 30 days total immersion in water , an expanded polystyrene panel had absorbed 0.2% of its total weight of water.

Ssound pretty good to me on the damp-proof front. Only weak point being the joins.

If it sounds pretty good to you mountain, why do think the installation manual says "must not" be used to isolate damp or moisture ?

 

[mointainwalker]

@mac 391

I have absolutely no idea why they write that

All I can tell you is that I read MI with, as far as i can say, the intelligence I think i have, and when their ideas become ridiculous I have to pull the comunications cord.

I think we are are all aware that that MI's are becoming more and more stupid., requiring you to wear full-body chemical warfare suits to use white -spirit etc and that users have to decide what they wish to do and what they feel is reasonable.

 

[chadfieldpropertyservices]

The fact that you have worse damp in sunny weather suggests condensation, especially if there has been no heating for some time, the air on warm sunny days actually contains more water vapour than on cold days and just as peoples glasses steam up when they come into a warm pub on a cold night, the same is happening to your house. are the solid floors original withour damp membrane or are they modern with a membrane? you can sometimes see the membrane around the edge of the slab, either way the floor needs a dpm between the concrete and the covering.
Expanded polystyrene is ineffective as a vapour barrier as there are many voids between the particles than damp air can permeate. personaly I never ever use eps as an insulant, cheap n nasty stuff, kingspan of similar pu board with its aluminium foil coating is vapour proof and a better insulator. we have used expanding foam to dot n dab 25mm pu boards and plasterboard onto 9" brick and 20" stone walls, the buildings are now both warm and dry which is something they would not have been if the brainless tart of a conservation officer had had her way with lime plaster.