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

[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