Insulation/concrete carport help?

[TRRZ]

I’m looking at insulating a carport with a concrete ceiling, with a living room directly above it.

I’d like to use 100mm PIR insulation, as I don’t think using anything thinner would make the job worthwhile. I have an installation method in mind, but I’d appreciate confirmation on whether it is suitable, along with any advice or constructive criticism.

temporarily prop the PIR boards against the concrete ceiling and bond them in place with a suitable adhesive. While the boards are still supported, I would also install a suitable number of mechanical fixings with PIR insulation washers.

Once the entire ceiling is insulated, I would fit timber battens over the PIR at 400mm centres, fixing through the insulation and directly into the concrete. This would effectively secure the PIR boards between the battens and the concrete. I’m unsure whether compression sleeves or spacers would be required to prevent the insulation from being crushed.

would then install two layers of fire-rated plasterboard over the battens, tape and seal the joints, and finish it with a suitable exterior-grade paint or coating.

Does this sound like a sensible approach?

 

[stevie888]

You don't need the mechanical fixing step you've got the board bonded and temporarily propped so just go to the battens.

You don't need sleeves.

I would want to cover withcement board since it's external,