Insulated plasterboard help

[MK22]

Hi everyone
I’m looking at fitting insulated plasterboard, we have empty cavity walls.
If you can help with the following questions that would be much appreciated;
Do I need to remove the old wallpaper and plaster before attaching? Plaster seems fine.
Id like to use mechanical fixings not leaving an air gap, do I need to be concerned about cold bridging where the fixings are used?
Do I need to notify building regs?
What’s the best way to seal all gaps to prevent any heat transfer?
Do I need foil backed insulated plasterboard?
Thanks.

 

[Wayners]

Wallpaper will degrade over time so not a good surface to stick to. Your mechanical fixings will hold forever if you are using any.
Plaster can stay on
Why you using insulated plasterboard if you have a cavity? Just for interest...
Are you aware of spray cork coatings.

 

[MK22]

Wallpaper will degrade over time so not a good surface to stick to. Your mechanical fixings will hold forever if you are using any.
Plaster can stay on
Why you using insulated plasterboard if you have a cavity? Just for interest...
Are you aware of spray cork coatings.

Cheers Wayners.
Plan is to use mechanics fixings, so does wallpaper still need to come down? I want to use the Twist fixings, so any concern for cold bridging?
Wanting to go for insulated plasterboard as external insulation is a no go, and I’ve read too many horror stories of retrospective cavity wall insulation. Is there a better option?
Thanks

 

[foxhole]

You can leave wallpaper for mechanically fixing but easier to fix with fixing foam ( but would require wallpaper removal ) and a few mechanical fixing per board .
No cold bridging . Foil back is most effective .