fixing 62.5 mm PIR insulated plasterboard to ceiling

[whatsthenews]

Hi,
What's the best way to fix to ceiling?
We have 50mm celotex between joists and now about to put the 62.5 insulated plasterboard up.
We've got 90 mm plasterboard screws.
Bearing in mind the cost of the material, the fact that we'll be close to the edge and the depth we're fixing through, would people recommend pre-drilling, and if so, what with please?
Anyone used plasterboard adhesive plus mechanical fixing?
Thanks.

 

[23vc]

Have you already got the boards? 50mm PIR and normal plasterboard massively easier

 

[cdbe]

What are you pre-drilling? The only thing that helps is that you can come further back from the edges of the boards and screw at a slight angle to hit the joists. The biggest difficulty I found was that they don't bend like plasterboard and there's a narrow margin between pulling the boards tight to the joists and bursting through the plasterboard. Some kind of filling adhesive between board and joists might be a good idea if they are more than a tiny bit uneven.

 

[catlad]

Expanding board foam as well as fixings or 120mm plasterboard screws

 

[whatsthenews]

Expanding board foam as well as fixings or 120mm plasterboard screws

Thanks catlad. We're novices (in case you hadn't realised!)Does the expanding foam not make a mess and stick before you've got the board in position? What brand do you use? We have 100 mm pb screws?

Have you already got the boards? 50mm PIR and normal plasterboard massively easier

yes, we thought about buying them separately, but didn't in the end. Looking forward to getting 8 x 4's up there, but we think we have a plan!

What are you pre-drilling? The only thing that helps is that you can come further back from the edges of the boards and screw at a slight angle to hit the joists. The biggest difficulty I found was that they don't bend like plasterboard and there's a narrow margin between pulling the boards tight to the joists and bursting through the plasterboard. Some kind of filling adhesive between board and joists might be a good idea if they are more than a tiny bit uneven.

We would be pre-drilling through the joists and the noggins round the perimeter (which is where we're most worried about hitting the wood,especially now that since taping all the joints it's difficult to see exactly where wood stops and PIR starts. It's a 1960's utility room at the back of the garage. We had to add a lot of extra noggins as , even thought there had been a ceiling with tongue and groove over it, there were lots missing. Nothing is even, not even the spacing of the joists, so we had to double up in places. Been a bit of a nightmare TBH. Some expanding filling adhesive sounds like a good idea.

Can I also ask what tape people use for taping the vapour membrane?
Bought Mammoth DPM tape and it came off everywhere except the vapour barrier! Can we just use the foil tape?

 

[JP_]

I've used Everbuild's pinkgrip foam. You spray it on, wait 4-5 minutes, then press on and hold in place (the longer the better).
Should not expand out, and holds tight. If doing a ceiling I'd chuck some screws in too though - I've only done walls with it.

 

[whatsthenews]

I've used Evervuild's pinkgrip foam. You spray it on, wait 4-5 minutes, then press on and hold in place (the longer the better).
Should not expand out, and holds tight. If doing a ceiling I'd chuck some screws in too though - I've only done walls with it.

Cheers. So, re the "holding in place" for the ceiling could be achieved by the prop and getting some fixings in ASAP? How long do you still have some manoeuvrability for?

 

[JP_]

I just leaned on it. But props for ceiling. If I was doing a ceiling, I would probably just screw in place - only reason to stick, I think, is if there is no timber to screw into. Also, sticking can help with uneven surfaces.

If you sticking, I'd wait the 4 minutes, push it in place, then put the supporting screws in after a few minutes holding it in place, then it won't be able to move anywhere.