damp in loft

[sm_jamieson]

Just been in the loft to get some baby clothes (wife was convinced it was g oing to be a boy ...) and I noticed there was *some* damp. Just a bit of co ndensation on the angle iron shelving, plastic boxes, etc. Nothing dripping , mineral wool does not feel damp, but there is some condensation. And its not that cold at the moment.

The roof is rosemary tiles, no sarking or felt, no eves vents (no real dept h of soffits). It was always bone dry before, but I have recently added a good depth of wo ol insulation so its a lot colder in there. At present we have no extractor in the bathroom so maybe some of the humidi ty from there is making it into the loft. The bathroom ceiling is skimmed p lasterboard without an vapour membrane. I had assumed that the gappy tiles would vent sufficiently, but perhaps I n eed a bit more up there. What type of vents are suitable to use in with rosemary tiles (ideally fitt ed from inside)?

I could also fit some vents in the 9" gable wall if required. And perhaps paint the top of the plasterboard with an oil based paint. Ideally I need to sort this before the winter arrives !

Cheers, Simon.

[sm_jamieson]

going to be a boy ...) and I noticed there was *some* damp. Just a bit of condensation on the angle iron shelving, plastic boxes, etc. Nothing drippi ng, mineral wool does not feel damp, but there is some condensation. And it s not that cold at the moment.

pth of soffits).

wool insulation so its a lot colder in there.

dity from there is making it into the loft. The bathroom ceiling is skimmed plasterboard without an vapour membrane.

need a bit more up there.

tted from inside)?

Oh yes, there is an unused grille in the bathroom ceiling that is stuffed w ith insulation but might not be moisture-tight, and there is a light in the ceiling that almost certainly is not. The loft hatch fits pretty well and has draft exclusion strips.

Simon.

[Another John]

Personally I wouldn't worry just yet: it's a pain in the neck, but I'd just check quite regularly for the next few weeks.

My point being that at this time of year there are quite sweeping changes in the atmosphere (cold air, warm air, damp air, dry air...) and you might have been up there just after a change had happened.

Like you, I'd have thought that 'naked' tiles would ventilate better than anything else!

2p John

[Edgar]

I wouldn't worry yet. Watch it for a while and see if it dries out.

You say you have gappy tiles. They will let in damp air from outside. At this time of year we have very high levels of humidity. So the loft gets full of very damp air. Then overnight there's a clear sky and the temperature of the tiles falls dramatically. Condensation on the underside is the result. Next morning the sun shines and the tiles warm up driving the moisture into the air again. A less humid day arrives and all is well.

I recently went into the loft of a house with just that kind of roof. It had gaps you could see through between the tiles. In winter the owner told me that snow lightly covered the things in the loft. The things included lots of books and papers which I'd have expected to be ruined. They weren't. Old curtains had been thrown over them loosely and these had soaked up dripping moisture and dried out again.

What you really don't want is for the fabric to get wet and stay wet. If there are no gaps in the tiles then that's when loft ventilation has to be introduced in case moisture does get in.

One thing you can do is make sure water vapour isn't getting through the ceilings. Light fittings and pipes sometimes have big holes through the ceiling. The top of the airing cupboard is one place to look. Seal these.

If it doesn't dry out I'd think again.

I remember that at this time of year Land Rover carburettors (Solex) had a tendency to ice up on cold days. (Other cars with Solex carbs suffered too.)

Edgar

[harryagain]

The roof is rosemary tiles, no sarking or felt, no eves vents (no real depth of soffits). It was always bone dry before, but I have recently added a good depth of wool insulation so its a lot colder in there. At present we have no extractor in the bathroom so maybe some of the humidity from there is making it into the loft. The bathroom ceiling is skimmed plasterboard without an vapour membrane.

I had assumed that the gappy tiles would vent sufficiently, but perhaps I need a bit more up there. What type of vents are suitable to use in with rosemary tiles (ideally fitted from inside)?

I could also fit some vents in the 9" gable wall if required. And perhaps paint the top of the plasterboard with an oil based paint. Ideally I need to sort this before the winter arrives !

Cheers, Simon.

The first thing to check is your trapdoor which needs to be airtight to keep warm moist air from leaking from the house into the loft. Also anything else that might be allowing air to pass. Including from next door if appropiate.

[Tim Lamb]

In message , Another John writes

Classic time for cast iron workshop machinery to rust. Two or three days low temperatures followed by high humidity leads to condensation on metal surfaces. Foggy here, yesterday morning.

[Roger Mills]

Are there any water tanks in the loft - e.g. cold header tank for DHW and/or Fill & Expansion tank for vented CH system?

If so, are they covered? Could the CH be pumping over and making the water in the F&E tank hot?

[sm_jamieson]

as going to be a boy ...) and I noticed there was *some* damp. Just a bit o f condensation on the angle iron shelving, plastic boxes, etc. Nothing drip ping, mineral wool does not feel damp, but there is some condensation. And its not that cold at the moment.

depth of soffits).

f wool insulation so its a lot colder in there.

midity from there is making it into the loft. The bathroom ceiling is skimm ed plasterboard without an vapour membrane.

I need a bit more up there.

fitted from inside)?

No tanks any more, we just have a combi - for better or worse ! Simon.

[Roger Mills]

OK, it ain't that then! It was just a thought because we got a lot of condensation in our loft some years ago (probably 20!) when the system was pumping over.

[Andrew Gabriel]

I suspect it's just temperature/humidity changes dropping some dew on the high heat capacity items.

I would periodically check the timber with a damp meter, until you have enough confidence it's not getting too damp.

[Martin Bonner]

It's worth going round making sure there is no way for warm, moist air leak into the loft - not so much to prevent damp (the gaps under the tiles will do that), but to keep the house warm.