False / Suspended ceiling in conservatory advice

Hi all, I'm thinking of now creating a false ceiling by hanging joists - 3x2 probably. I will create a small rebate in each end and they'll sit on the conservatory 'walls'.

I will then clad the ceiling with some upvc - either t&g or plain panels.

However I'm a bit stuck on the insulation. I was going to put loft roll on top or between the joists, but would I need a vapour barrier? If I did, where would I install that? Before the cladding?

Alternatively I could staple mutlifoil to the joists, roof side, which would act as the insulation and vapour barrier - but the thermal properties aren't as good as loft roll.

I know this isn't standard, and I'm not expecting miraculous results. I also don't want anything too permanent, hence the lack of fixing to the frame, as we're not going to be in this house forever.

Any advice on the insulation bit?

Thanks

Two weeks since I posted this, haven't started yet. Has anyone got some advice for me?!

Well, lockdown happened last year and I never got round to doing this. It has to be done now though as my partner is going to run a business from there. Any advice on the above anyone!?

Another issue which I've thought about is a lack of ventilation in the 'roof space' - is there a danger that void could get too hot in the summer?

Thanks all

You will need ventilation in the void above the suspended ceiling, you also need to be careful of the additional weight you are loading onto the structure.
Post a pic.

Thanks for the reply. Yeah I am worried about the weight, hence why I'd rather go for some light insulation and hollow soffit cladding. I've seen the plasterboarded examples online, but all that weight would concern me tbh.

Any idea where/what I could do about the ventilation? I read on another forum someone drilled some holes in the wall plate, but not sure where.

Most conservatories have ventilation at eave and ridge line...Worth checking.

Personally I'd be considering 100mm celotex as my insulation, it weighs nothing and could be held up by some very spindly "joists" which would also hold up lightweight uPVC cladding. Taping the joints and perimeter of the celotex with foil tape will give you a vapour barrier.

Just wondering if you went ahead with the false ceiling on the conservatory and if you did, how it has been as I have just done similar but with plasterboard