Having taken steps to add extra insulation in the loft floor, put chip board flooring down , add extra sofet vents ( every 2-3ft) I still get condensation on the roof felt when the temp drops below 2-3 degree Celsius.
I note the comments that water vapor can seep through plaster but when the condensation occurs it takes 4-5 bath towels to remove it. That is a lot of vapor each day.
I thought removing the hot and cold tanks from the loft would help. A couple of builders have been in giving me quote to put airbricks in or roof tiles with vents in but I'm not convinced they will generate enough circulation of air to solve the problem.
A colleague at work who got a a metal shed had load of condensation (almost like rain inside!) , he tried to improve the air flow - no change, and was advised to put insulation actually on the sloping part of the roof so the air filled with vapor would not hit such a cold surface and condense .
What do you reckon?
You need to find out why there is so much condensation in the loft.
When the central heating is running go and have a look at the small header tank and see if the water is hot (it should be cold).
If this is OK buy a cheap hygrometer and put it in the rooms directly under the loft, you should get readings at about 50% - if they are a lot higher investigate.
So no longer have any tanks in the loft.
I did think that removing the tanks would help but it has not.
In fact it is probably worse but that could be because we had a much colder snap before Christmas in 2009.
Will try the hydrometer suggestion out. Many thanks
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