Wet rafters and condensation

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We've just taken the decorations out of the loft and noticed condensation on the felt and the rafters are wet. I'm mortified as we've never seen this problem before and we've lived here for a few years.
We seem to have less frost on our roof than the neighbours so I wonder if our insulation isn't great, though our house is very warm. We have good ventilation up there I guess as you can feel a draught when you go up.
Is this because we've been up and down in the loft recently getting halloween decs and let the warm moist air up there?
I've read through some threads on here and it seems it could also be from not using the extractor fan in the bathroom. Our kids love long hot showers!
Will the rafters dry out? Is this a big problem? My husband says I'm worrying over nothing as usual.
 
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Does anybody hang wet washing around the house or on radiators?

Are there holes in any ceilings, especially the bathroom, e.g. for downlighters?

Are there any water tanks in the loft? Do they have lids? Are any warm?

Why don't you use the bathroom extractor?
 
Yes we dry washing in the bathroom and round the house when the weather is wet. We always forget the bathroom extractor but I have told the family they must use it from now on.
There is a large fluorescent light fitting in the ceiling of the bathroom. There is a large round hole cut in the ceiling and it sits in that.
Water tank in loft is a cold tank and insulated.
Sounds like there are a lot of things that could be making it worse
 
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Yes.

Water vapour is lighter than air so it will rise through the house until something stops it.

Does the loft tank have a lid? Is the water actually cold? Feel it.

You can get an electrician to wire the fan so it automatically comes on with the ceiling light. Photograph the fan please as it may be weak or noisy. If it seems OK you can leave it constantly on. Electricity cost of a fan is negligible.

Photograph the hole in the ceiling from above please.

Draping wet washing over radiators is no worse than throwing buckets of water at the walls.
 
Will get the kids to sort photos when they get home and will check the tank water in a minute. The fan is fairly new, put in when the bathroom was fitted about 4 years ago. It rotates by itself most of the time but when you pull the cord it goes really fast.
The washing is a big problem at this time of year
 
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Tank cold. I used to dry the washing in the downstairs shower room but this year I moved it upstairs to the bathroom as it dries quicker on the clothes horse upstairs. I wonder if this is the culprit? Will the rafters dry out if I can find the source of the damp air? It was dry as a bone up there until recently.
 
Do you have an extractor fan in the shower room? If powerful, it will suck the water vapour out through the wall, speeding drying and keeping the house drier.

If you ventilate the loft and stop adding water to it, it will dry out. On a sunny day with the heating off and no wet washing, open the loft hatch and the back door. There should be a strong draught through the hatch.
 
Yes, it comes on when you turn the light on. Would it be ok to leave the light and fan on all the time?
 
You have frost on your roof, your roof is freezing. It's pretty much inevitable that any warm air leaking will cause condensation.

Just keep an eye on it and see what it's like when it's warmer and check that it's not been so wet over a prolonged period that moisture has dripped into your insulation and soaked through to the bottom - that'll never dry out. If over the course of the year the rafters are dry and this is exceptional, then it's nothing to worry about.
 
when we see the ceiling hole, there will be a way to prevent steam rising through it. You probably won't need a fire hood, but they are quite cheap.

Modern energy saving, LED and fluorescent lamps run fairly cool (but old incandescent, and especially halogens, need extra care as they can get very hot and may cause scorching or fire, so should not be just covered).
 
Kids have gone out so can't get a photo. I've had a look at it and it is only a tiny hole, just large enough for the wires to fit through.
 
In that case, you can put loft insulation over it. look for any other holes, e.g. for pipes and you can stuff mineral wool round them. Plaster itself is permeable, and steam can pass through it unless it has a metal foil layer, but if you had big holes, they would have been a problem worth fixing. If the fan is near the ceiling, and fairly powerful, it will suck the worst of the water vapour out, over time.
 

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