Battening over 100mm PIR insulation

[frank999]

How do you fix battening over 100mm thick PIR insulation.

I need to go into standard brick work (an old chimney breast).

My thoughts are to 'glue' the PIR (foil backed both sides) to the brick work with expanding foam, then fix 25x50mm battening with some sort of long fixing that goes through the PIR and into the brick work.

Insofast do something that doesn't require battening, but it seems an expensive way to put up plaster boards, £15 + delivery for just 20 fixings. plaster board screws are recommended every 150mm, so you'd get through quite a few of these.

I've thought of using a series of wooden battens on the brick wall, and simply use very long wood screws to go through the 100mm PIR, but that would require 150mm 6 screws - that would probably split the battens.

 

[noseall]

My thoughts are to 'glue' the PIR (foil backed both sides) to the brick work with expanding foam.

Have you considered gluing the plasterboards to the PIR foam boards in a similar fashion?

 

[frank999]

No I haven't, with expanding foam ?

Not sure what will bond to the Ali coating each side.

 

[frank999]

Guess I could create a stud wall fixed to the brick work and then infill with the celotex, that would then provide a fixing point for the plasterboard.

I would still have to attach 25x50mm battens to the 45x95mm stud timber though, what a faff this mismatch of sizes is !

 

[noseall]

Not sure what will bond to the Ali coating each side.

My thoughts are to 'glue' the PIR (foil backed both sides) to the brick work with expanding foam.

Well if it works for one side then it is sure gonna work for t'uther.

 

[frank999]

Tried some 'general' expanding foam, which seemed to stick it initially, but I think it was more like a sort of suction that held the foil backed PIR, I pulled down on one edge and it came off without signs of any bonding to the foil surface.

I've driven a 4.2 x 100mm plaster board screw through a 25mm piece of battening, straight into the Toplite block and its held it fast.
I could glue the 25mm PIR to hold it - then screw the plaster board over using these 100mm screws, although thinking about it, where there was the sand and cement mortar, holes would require pre-drilling.

 

[catlad]

I have stuck plenty of insulation with expanding foam, it needs to be held in place for approx 15 min until it cures and if you are sticking it to brick then spray some water on the brickwork first.