Hi, i have read the previoue loft condersation advice given, my loft on the left of the roof there is felt which has wet batched on the lower section of the roof and on the right side of the roof there is a black plastic type of material under the roof tile which is full of condersation, you can see the water droplet on all of the surface area, now and again you can hear water droplets, i have a bathroom under the right side of the loft whitch does have an extracor fan, and we leave the window open about 2inched. the loft is insulated and i was putter extra lolft insulation at each end of the loft because it has an old pink type of inulation, in the middle of the loft i have a good quatity 200 thick insulation 3 yrs old now. and today i have put the same insulation on the right side of the loft, havent had time to do the left side yet or the loft hatch.
the joist on the right side of the loft which touches the roof is wet in looking dont know if this is just due to condersation, and of course there is a lot of snow on the roof could this the problem. there in no ventilation in the roof, but i can feel cold brease in the loft coming from both sides.