Reducing condensation in the loft

TuppenceHapenny

Am I correct to think that running a fan in the loft for long periods should dry the loft and reduce any condensation that may form up there?

Also, there's no down side to this given the fan is very cheap to run?

P933alilli

Very interested in this as i had a leak from the chimney which needed repointing and flashing, the job was done but a stain on my living room ceiling prior to getting it done still hasnt gone and the roofer blames condensation on the insulation up in the loft!

Albermarle

TuppenceHapenny said:

Am I correct to think that running a fan in the loft for long periods should dry the loft and reduce any condensation that may form up there?

Also, there's no down side to this given the fan is very cheap to run?

Condensation is usually caused by poor ventilation, so if the loft is poorly ventilated, not sure just moving the same air around will help that much. It is not going to do any harm though and may help, but the bottom line is that there should be no condensation in the first place. 

MysteryMe

P933alilli said:

Very interested in this as i had a leak from the chimney which needed repointing and flashing, the job was done but a stain on my living room ceiling prior to getting it done still hasnt gone and the roofer blames condensation on the insulation up in the loft!

A stain from pre repair is not going to disappear. You need to use something like Zinsser Cover Stain and then re paint the area.

Lorian

High relative humidity is pretty hard to avoid in the loft this time of the year, even if well ventilated. If you are trying to stop it condensing on surfaces avoid leaving the loft hatch open and sending lots of warm moisture laden air up through the hatch.

ThisIsWeird

Yes, we need more info from TH - what is the actual issue, and is it just an occasional 'winter' one?

P933, is this stain still actually damp to the touch? How long ago was the leak repaired? 
It shouldn't be prolonged by 'condensation' - the loft insulation should help prevent this - but the presence of insulation may be slowing down the drying time as the top surface isn't being directly ventilated - not helped by it being winter, and darned cold up there.
Just give it some time. If you wish to temporarily lift the insulation away from that area in order to 'air' it better, then fine, but barely worth it. In warmer climes, this would dry in a few days.
If it is actually dry, but still stained, then it needs a good clean followed by a stain block to seal it.

P933alilli

ThisIsWeird said:

Yes, we need more info from TH - what is the actual issue, and is it just an occasional 'winter' one?

P933, is this stain still actually damp to the touch? How long ago was the leak repaired? 
It shouldn't be prolonged by 'condensation' - the loft insulation should help prevent this - but the presence of insulation may be slowing down the drying time as the top surface isn't being directly ventilated - not helped by it being winter, and darned cold up there.
Just give it some time. If you wish to temporarily lift the insulation away from that area in order to 'air' it better, then fine, but barely worth it. In warmer climes, this would dry in a few days.
If it is actually dry, but still stained, then it needs a good clean followed by a stain block to seal it.

Thanks for the reply!

            The stain feels cold to the touch. When i rub my fingers across the area  some emulsion comes off, so i end up with slightly white finger tips. The chimney was repointed in June and fresh cement put in plus some flashing but then in October i thought the stain on the living room ceiling had expanded. The original roofer was busy so i contacted another who, on inspection, said that there was a small gap near the lead soaker and this was letting water pass through. That was done mid- November. The damp stain hasnt got worse but isnt drying up fully. The roofer went in the loft again, early december, and the insulation was damp near the chimney. He lifted it slightly and put some pan underneath and said he was pretty sure it was condensation which, as you suggested, would probably dry out in summer. He reckoned some of the insulation had been pulled back probably from when a plumber put the new combi boiler in 4 years ago. The boiler is at the other end of the bungalow. At one point he asked could i not go up with a dehumidifier.

   He said that some of the old insulation could be taken out and a couple of new rolls put in but hasnt got back to me yet ( that was just before christmas and he said the person dealing with loft insulation would be back in 1st week in january. I dont want to spend anymore. First roofer charged £360 and the second charged £425! Maybe its simply a matter of needing more time as alluded to and putting two new rolls of insulation down? I dont think i should be spending more on a job where ive paid nearly £800 already and been asked could i take a dehumidifier up myself for the privilege of the original problem not been fixed?

FreeBear

Putting a dehumidifier in a loft will be a waste of time. There will be loads of damp air being drawn in from outside that would overwhelm the dehumidifier.

If you are reasonable fit & active, putting down loft insulation isn't very difficult. It doesn't require any real skill or specialist tools. A dust mask, gloves, and perhaps disposable overalls is all that is required. Oh, and if the loft isn't boarded, you do need to be very careful about where you put your feet.

Or just leave it to dry out during the summer months - Even during a miserable summer, there will be enough days when it is baking up there to dry everything out.

P933alilli

FreeBear said:

Putting a dehumidifier in a loft will be a waste of time. There will be loads of damp air being drawn in from outside that would overwhelm the dehumidifier.

If you are reasonable fit & active, putting down loft insulation isn't very difficult. It doesn't require any real skill or specialist tools. A dust mask, gloves, and perhaps disposable overalls is all that is required. Oh, and if the loft isn't boarded, you do need to be very careful about where you put your feet.

Or just leave it to dry out during the summer months - Even during a miserable summer, there will be enough days when it is baking up there to dry everything out.

Thanks! No, i'm not fit enough to be doing the job myself as i have wear & tear in my lower back and knee. Also, there are no walking boards towards the chimney breast area so i'd be balancing on the loft beams.  I may just hang on until summer and see if it dries out, as long as it doesnt expand anymore!

TuppenceHapenny

ThisIsWeird said:

Yes, we need more info from TH - what is the actual issue, and is it just an occasional 'winter' one?

The house isn't always heated properly in winter and the loft hatch is sometimes left partly open to allow heat from the house into the loft (to help prevent a frozen pipe), so there will be more moisture than normal entering the loft, though only in very cold weather.

I wonder if using a fan to circulate air around the loft will also induce air to flow in and out via the soffit vents, therefore helping to remove any moisture that the circulating air has evaporated?

FreeBear

TuppenceHapenny said:

ThisIsWeird said:

Yes, we need more info from TH - what is the actual issue, and is it just an occasional 'winter' one?

The house isn't always heated properly in winter and the loft hatch is sometimes left partly open to allow heat from the house into the loft (to help prevent a frozen pipe), so there will be more moisture than normal entering the loft, though only in very cold weather.

Lag the pipes. And if you still think they might freeze, put a trace heater under the lagging. Connected to a thermostat that only switches on when the temperature falls below say 4°C, it shouldn't consume too much electricity.