[Miller]

We are about to build a kitchen extension with a pitched internal ceiling. To comply with building regs, the voids between the joists are to be filled with two layers of Celotex insulation.

We wanted to install downlighters in the pitched ceiling, but there is obviously a fire risk or lamp failure because of the insulation. Now I know you can get fire retardent downlighters, but there is obviously an issue with heat loss, and I don't think the building inspector will allow me to cut away the celotex around the downlighter. I've done some research and there is a standard called 'IC Housings' (Insulation Contact), but I can't see of many fittings complying with this standard (except this one CS5-IC - Photonstar Lighting - Performance Ecolighting). Has anyone had this problem or knows of a solution?

[stevelup]

It's not just heat loss - you break the vapour barrier as well.

Really, the best advice would be to either check with your BCO, or whoever drew up your original plans.

It really depends how flexible your BCO is though. You can get some pretty funky looking surface mounted stuff which may prove to be less hassle...

[DaveChester]

If you did decide to go surface mount I would look at track lighting. Its an extremely flexible solution and can look superb.

[hornydragon]

normally you drop the plaster board down to allow clearence for flush fitted items without touching the celotex.

[Miller]

Thats an idea, I'll speak to the builder.

[davee]

You would normally fit the Celotex between the rafters or above and between the rafters depending on the u value you require and the size of the rafters.
This should leave you space for running cables at least and possibly fitting lights if there is space.
Just to bang on about it if you fit fire rated downlights you must fit the correct lamps. These throw the heat forward wheras the standard diachroic lamps throw the heat back and will lead to overheating