How can i cure condensation in my boarded loft. I have some insulation under the boarding but I suspect not enough. It condenses on the underside of the non permeable roofing felt and is worse above the bathroom (the source of most moist warm air). Do I just need to provide ventilation in the loft and if so how or should I stop the moist warm area getting in. How do I do this...would a polythene vapour barrier under the boards work and better insulation..do I need to provide a gap between the top of the insulation and the bottom of the boarding. I have spots recessed in the ceiling which is probably where some moist air is getting in..shoud I enclose these within the roof or will this create a fire risk. If I wanted to keep the loft as a warm area how would I deal with the warm air..I could provide a vapour barrier behind new boarding fixed to the eaves but how would I vent the warm air at the top of the roof.

George, December 2009

An even cheaper solution may be to cut a few holes in the roof felt.

Contrary to popular belief, roof-felt is there for one reason only - to allow protection from rain whilst the roofers are putting on the roof. Year ago, they only replaced a few tiles at a time, leaving it watertight each night. Then someone thought of putting a felt down so the thing was watertight, then do the whole roof over several days.

Once the roof is on, it should be watertight, and if it isn't you want to know a.s.a.p., so the felt is no longer required, and often reduces the ventilation previously afforded on older rooves built without it.

Eric Davey, March 2010

Hi George
The bigest reason you have condensation is the loft is because of a couple of thing. I have written this article for people use and hopefully understand why.

Here is the link.
http://www.projects.toolvolt.co.uk/listing.php?id=1
This is my new site that I am writing to give info on topics like this and will be writing more soon.

My loft is the same as yours, fully boarded and with minimal insualtion. My boards were condensating on the underside to, so now have topped up the insulation and that stopped that problem.

But soffit vents are the best answer, apart from replacing all your roofing felt with new breathable type, and this job most people can do themselves.

Now with your inset lights, all I done was to cut out the insulation around them and drill 3 25mm holes over then in the board. If you have a transformer with yours, like mine, feed this through the hole and leave on the board, this will make sure it does not over heat. Don't worry about more warm air escaping, as this will be so little that the vents will take care of cooling it down and most important is keeping the air moving.

If you wanted to keep the loft space a little warmer then you can fit a product called Thermawrap Loft Insulation.
Here is the link
http://tidd.ly/fbbc12cf
This can be stapled to the under side of your rafters.

I hope you found my article of use to you. I f you have any Q's please do let me know and will try to answer them.

www.toolvolt.co.uk

Joe S Dybowski, December 2009