installing a boiler onto plasterboard and insulation...

[xelaris]

I've read already some posts addressing this topic but most of them are about installing a boiler onto plasterboard without any insulation behind (just a void of 2-2.5cm...
In my case there is a 40mm urethane board (Celotex, Kingspan type) between thermalite blocs (the wall) and the 12mm plasterboard....
I've come up with the following solution:
Drill the thermalite blocks and install some resin fixings (e.g. Fisher) - these should accommodate the thickness of the urethane board and the plasterboard (and a little more to allow the nut to be tightened) - so the bolts should extend about 70mm from the wall (the overall length of the bolts is going to be around 150mm - 80mm inside the thermalite block).

Has anyone tried something similar to this?

 

[foxhole]

You could install 50mm of ply to the area removing the plasterboard and insulation and then fix to that, thermolite does not hold fixings well, most will pull out .Depends on which blocks you have thermolite come in 8 varieties.
These are good for soft block fixing.
http://www.plasplugs.com/acatalog/Thermal_Block_Fixings.html

 

[xelaris]

You could install 50mm of ply to the area removing the plasterboard and insulation and then fix to that, thermolite does not hold fixings well, most will pull out .Depends on which blocks you have thermolite come in 8 varieties.
These are good for soft block fixing.
http://www.plasplugs.com/acatalog/Thermal_Block_Fixings.html[/QUOTE]

maybe I can cut a small area for the ply - enough to cover the boiler's bracket - let's say a rectangle of about 400mm x 200mm...

 

[foxhole]

You could install 50mm of ply to the area removing the plasterboard and insulation and then fix to that, thermolite does not hold fixings well, most will pull out .Depends on which blocks you have thermolite come in 8 varieties.
These are good for soft block fixing.
http://www.plasplugs.com/acatalog/Thermal_Block_Fixings.html[/QUOTE]

maybe I can cut a small area for the ply - enough to cover the boiler's bracket - let's say a rectangle of about 400mm x 200mm...

Yes that's the idea.