Pink grip or low expansion foam

[Cpd]

I am adding 25mm of calotex to the underside of my rafters which have 170mm already in them. I will then be putting up osb and then plasterboard.

My question is should i use everbuild pink grip or soudel low expansion foam to initially hold them in place. 

I imagine i would cut the sheets to size, foam or pink grip the sheet and push it into place, temporarily fix a batten across to hold the sheets in place until its all finished and then remove battens and foam up the gaps, cut back and tape the joints. Its just a matter of what would work best on that initial pushing up into possition. Once the osb is screwed up  its not going anywhere. 

Or should i be using something completely different?  Thanks in advance. 

 

[Onoff]

How about spray adhesive? Surprisingly sticky!

 

https://www.screwfix.com/p/no-nonsense-contact-adhesive-natural-500ml/32657

 

Failing that a "grab" adhesive. Whatever's cheapest I reckon.

[Nickfromwales]

40 minutes ago, Cpd said:

Or should i be using something completely different?  Thanks in advance. 

 

On the last one I fitted 25mm celotex with 50mm screws and some penny washers. Just sink them so the washer pulls in and bingo. Use the foam to fill the gaps around the perimeter, and foil tape the butt joints. 8 or 9 fixing per sheet is ample, but remember NOT to leave any screws proud or they'll hold the OSB proud. 

[CC45]

I nailed my 25mm celotex using the surplus roofing (aluminium) nails - nice big flat heads on them + some penny washers.  Still up 2 yrs later.  Need to get some ply on to finish the job.