Dry lining/insulation/condensation problem

[ban-all-sheds]

My house (typical 3-bed semi) has solid walls, and the side wall not only faces north but is only a single drive-way width away from the next house (we have shared driveways here). So it gets no sun, and is always very cold in winter.

It's never caused any problems though, but we noticed recently that the section where we hang coats in the hall was very damp, and one of the coats had got some mildew spots. There was a noticeable film of condensation on the wall, which is papered and painted. The coats have been removed, and now (a week later), no sign of damp, so I'm pretty sure it was just condensation - cold wall, lack of air circulating there, damp coats now & then, and typical tightly sealed house with people breathing, cooking etc.

We don't have a general problem with condensation in the house, and I suspect the reason we've never had trouble on this wall before is that up until now there was a radiator on it, running along under where the coats hang, but earlier this year we removed that and installed a vertical panel to one side of this area.

I plan to insulate & dry-line it with battens/polystyrene slabs/plasterboard, and I have a few questions.

1) Should I first strip off the painted paper and take the wall back to bare plaster to allow it to breathe better?

2) Should I either tack a sheet of polythene over the battens or use foil-backed plasterboard?

 

[KonradFischer]

I would recommend to forget this ideas. All inner insulations I've seen got damp after a while, mold attack follows. They will suck condensate and never dry it out again. If you will cover it with a sheet of polythene there the condensation will first happen, after ageing of this awful material it will condesate behind.

My tip: If you will use your cold hall 'as a laundry', look that enough IR radiation will heat up the cold walls, this hinders condensation. Permanent heating!, otherwise your walls will cool off every night and suck up all the humidity of the warmer air of your hall. And air out the humidity as quick as possible. More details here: Wrong heating, wrong insulation and mold attack

Good luck!

Konrad

 

[oilman]

............... and typical tightly sealed house with people breathing, cooking etc.

.......................

I think this has most effect. Warm, draught proofed houses suffer this, our cold draughty house does not.

It's interesting that we have been instructed that a "warm cosy" house is a better and healthier place to live, where it is probably just the opposite.

 

[ban-all-sheds]

Konrad, thanks for he advice, even if it is very disappointing

Firstly, we don't use the hall as a laundry - we just hang coats there. We don't hang them up if they are soaking wet, but inevitably they will sometimes be a little damp, from mist/fog, or just from condensation from being cold on the outside.

Secondly, the hall, and the house are perfectly warm. True we have the heating a few degrees lower at night, but not off. It really wouldn't be possible to raise the internal air temperature of the house to the level where that wall would actually be warm, because it is insulated from the air by a layer of coats hanging there.... And, of course, the warmer the air in the house the more moisture it will hold, so it's likely to make things worse....

Hence my desire to provide a surface insulated from the outside wall that would be warm to the touch and this not get condensation. I had hoped that this would not lead to condensation behind the drywall, on the house wall, if I prevented warm moist air reaching it by use of a dpm or foil-backed board. But thinking about it, by the time I'd papered and painted the boards, it'd be well sealed anyway....

 

[KonradFischer]

Pardon, I won't disappoint you, maybe my post was too easy to misunderstand. With 'laundry' I mean a room where warm air with a lot of damp will reach colder walls and must condensate - as it mostly is in a laundry room. Perhaps bad joke regarding your hall, I do commit.

So I will give some remarks to better heating:

1st don't let cool off the walls by night. With permanent heating after some days and nights the walls will be warmer and you will use less heat energy to let them be warm. So maybe you can create a situation, where the walls are permanently warmer than the air - and then condensation is not more possible.

2nd let enough fresh dry air coming in by permanent airing. Then your humidity will not climb the rate to condensate at the walls. Opening the windows sometimes will not have this effect, because before opening the condensation happens and only additional big heat will force the fluid condensate water out again from the wall pores. So better you should take out the upper rubber from the windows, if there are some. If not:

3rd take away the double pane from one window or more (if there are some). You will get a 'must' condensate surface, which will take nearly all condensate out from the air and can safeguard your walls from condensation. Reason: Your pane(s) will offer the coldest surface, what the humidity will prefer to condensate instead the warmer surfaces of the walls.

Good luck!

Konrad

Much more details here: Better heating by IR radiation (only in german, sorry)

 

[oilman]

BAS, what may happen is the air gets out of your warmed rooms and into the hall. If you could arrange for the air to come into the hall and then go into the warm rooms, and then out (like up a chimney), you will be keeping the moisture in the air until you throw it out.

 

[ban-all-sheds]

The hall is heated, just like the rest of the house.

Most internal doors are open in the day and evening, and people in/out of various rooms....