Halogen ceiling lights, OK under insulation or not?

[RigidRaider]

Got 12v halogen lights in two bathrooms and the landing. Ceilings are very well insulated with about 350mm of glass wool. I've always taken care to leave a hole in the insulation above the bulbs to allow heat to escape, although I did come across some green plastic cylinders that were advertised as halogen light covers so I've tried these in one room and got them completely covered with glass wool. Over one light I've even tried a terracotta flowerpot! The hole in the bottom lets hot air out.

Is it OK to cover the bulbs or am I doing the right thing leaving them uncovered? They do get flippin' hot, although being bathrooms and landing they're not usually on for longer than half an hour at a time.

 

[mointainwalker]

You have to realise that air coming out of bathrooms is usually very moist.

If it is passing directly into the fibre-wool the moisture will eventually condense when it reaches its dew-point passing through the quilt.

This is terrible for insulation as wet insulation ( fibre-wool) type is useless when wet, just like your clothes if a bucket of water were thrown over you.

Solution is to fit a vapour-barrier ( plastic-sheet) between the ceiling and the wool to keep the moisture trapped on the warm-side of the insulation.

Sorry , don't know how to marrry this up with your down-lighters.

 

[RigidRaider]

Yes, I hadn't thought of that. Leaving them open would be best I guess because you'll have a column of hot damp air rising up the tube. Luckily our attic is very well ventilated so there's no sign of condensation anywhere.

 

[jeepster]

hi, have you considered making a box out of plasterboard then placing that over the down lighter, then butting the insulation against the box.
i know this is nt a perfect solution but will help to separate the insulation from the lamp.

 

[RigidRaider]

I've just realised that the lamps in the bathrooms are the "wet"sort, which are much better sealed against the ceiling than the regular sort so I doubt if there's any airflow.

There's still the excess heat issue though.

 

[jeepster]

hi, there is a product called a loft cap, you can fit these over the downlight fitting and then cover these with insulation.

google them, bc office aproved them for our extension but we have decided to go with low voltage ceiling lights.