Loft insulation with recessed halogen bulbs, condensation!!!

25 Jan 2010
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United Kingdom
Hi there, we are having problems with mildew around our halogen lamps (on our ceilings), I checked in the attic and found that the old lagging had been pulled away from the recessed halogen bulbs. I quick check on the internet and I found that this was sound advice. I decided to replace the insulation in our loft as it was very old and then board over the top (to increase storage space). I was hoping that the boards would trap the air and act as insulation. I have now discovered that mould is forming underneath the boards in the attic, above the halogen lamps. Would laying additional fibre glass insulation solve this problem? Would I need to construct a wooden framework for this, or just lay it over the top? Or is getting rid of the halogen lamps an easier, cheaper method? Please help?
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lofts are cold

houses are warm and moist

when warm moist air gets into a cold space condensation occurs

Cutting holes in the ceiling allows warm moist air from the house to rise into the loft

Hence downlighters are a cause of loft condensation, especially if they are in a bathroom.

You can buy fireproof hoods for downlighters to enclose them and cut the airflow. You could even make your own as boxes of plasterboard (non-flammable) and seal the joints with plaster. The temperature inside the enclosure will be high, so any cables entering it should be heat-resistant.

The boarding prevents ventilation and traps the moisture.

You also need to improve ventilation of the loft, and the underside of any boarding, so that moisture can escape. I suppose you could drill plenty of holes in teh boards above the lamps, or fitr a grille. The lamps will get very hot so if you want boards above them I think they need at least a plasterboard barrier (plasterboard is fireproof, chipboard is not)

Many people (including me) dislike holes in the ceiling and dislike downlighters. Filling the holes and fitting ordinary lamps would prevent this moist air getting up.

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