Celotex In The Ceiling = Spotlights

[Too Late]

Hi,

We have to install Celotex in between the joists in the kitchen ceiling. We are looking at installing sportlights but i have been reading about the difficulties with this.

I have an idea of using 150mm in the ceilings but where spot lights will be installed (LED fireproof) using 100mm to avoid the need to cut into the Celotex which is against BC.

Will that be ok?
All the building inspectors are onsite so i am unable to contact them to clarify at the moment

Thanks
N

[PAULJ5555]

Too Late said:

Hi,

We have to install Celotex in between the joists in the kitchen ceiling. We are looking at installing sportlights but i have been reading about the difficulties with this.

I have an idea of using 150mm in the ceilings but where spot lights will be installed (LED fireproof) using 100mm to avoid the need to cut into the Celotex which is against BC.

Will that be ok?
All the building inspectors are onsite so i am unable to contact them to clarify at the moment

Thanks
N

I was reading the celotex website this morning (sad I know) it says-

Can I recess my downlighters into Celotex?
No. Downlighters should not be recessed into insulated ceilings as they penetrate the vapour control layer (VCL) and act like a flue, drawing warm moist air into the roofspace where it condenses and drips back out of the fitting, possibly causing a fire risk.

If downlighters are to be used, they should be fitted in a false ceiling below the structural ceiling.

---

[jon-]

Out of interest, why are building control insisting on that much insulation?

[Too Late]

I am not sure why they wanted so much..

So to avoid having to cut the celotex, would my idea of using squares of 100mm where the spotlights go work? That means I would have enough headroom there for spots...
Thanks
N

[C0ffin D0dger]

PAULJ5555 said:

I was reading the celotex website this morning (sad I know) it says-

Can I recess my downlighters into Celotex?
No. Downlighters should not be recessed into insulated ceilings as they penetrate the vapour control layer (VCL) and act like a flue, drawing warm moist air into the roofspace where it condenses and drips back out of the fitting, possibly causing a fire risk.

If downlighters are to be used, they should be fitted in a false ceiling below the structural ceiling.

---

Hmm, our extension has a vaulted ceiling insulated with Celotex (or similar) and quite a few tilting GU10 spots. Now when they were put in they just chopped out a lump of the insulation where the lights were to go. I asked if it was okay to do that and was told that it needed to be done for fire safety but we may get an interesting pattern on the roof if it snowed. Now I'm all for a well insulated house but spot lights were really the only option in this build so we went with it. Must say never noticed any moisture / drips and on the odd occasion I've changed a bulb no corrosion or anything else on the fitting. The house is pretty dry anyway.

I have no concern over it to be honest aside from the reduced thermal efficiency of the ceiling but that was the price we had to pay for aesthetics.

[paulrockliffe]

There's a huge diference between a GU10 halogen bulb and the equivalent LED. With the halogens you'll have bulbs popping all the time if you don't provide ventilation, but the LEDs will probably be OK as they run a lot cooler.

[Frybywire]

Why can't you use Rockwool slab? Are building control getting kickbacks?

[hairyben]

Too Late said:

I am not sure why they wanted so much..

So to avoid having to cut the celotex, would my idea of using squares of 100mm where the spotlights go work? That means I would have enough headroom there for spots...
Thanks
N

Your idea will work fine but obviously last word has to be BC.

Failing that you can get very slim LED "light panels" although they're not usually dimmable

paulrockliffe said:

There's a huge diference between a GU10 halogen bulb and the equivalent LED. With the halogens you'll have bulbs popping all the time if you don't provide ventilation, but the LEDs will probably be OK as they run a lot cooler.

inadequate ventilation for LED light's and their drivers will lead to premature failure.