What are your preferred frame-fixings for battening on top of PIR insulation boards?

[MisterBoy]

I'm affixing 50mm PIR on a low brick wall and I plan to glue the boards to the wall first then batten on top with 25mm battens and mechanically fix through.

There's quite a few options for fixings - hammer/frame fixings, rawl+long screws, and various fixings that don't need a rawl. Prices vary a lot too. Just wondered what people prefer and why? What length of the fixing needs to be in the brick in my case?

 

[blup]

Screwfix do a good concrete screw, usually allow double the thickness of the batten in the wall, but for 25mm, 60mm would do.

Blup

 

[MisterBoy]

Screwfix do a good concrete screw, usually allow double the thickness of the batten in the wall, but for 25mm, 60mm would do.

Blup

Well there is the 50mm of insulation too. I can see 120mm and 150mm options, guessing 120 is just a bit on the short side.

Would you pilot drill through battens, pir into brick with a long drill then just whack the screw in? That's sounds quite a quick way to do things

 

[cdbe]

Personally I don't like long fixings going "blind" into masonry. I would fix the battens to the wall with normal screws and plugs, infill with 25mm PIR, overlay with 50mm PIR then plasterboard over the top with the screws going into the battens. The only thing is you'll need to find 85mm drywall screws.

 

[MisterBoy]

Personally I don't like long fixings going "blind" into masonry. I would fix the battens to the wall with normal screws and plugs, infill with 25mm PIR, overlay with 50mm PIR then plasterboard over the top with the screws going into the battens. The only thing is you'll need to find 85mm drywall screws.

What's the reasoning behind this - just not knowing what you might hit?

 

[cdbe]

What's the reasoning behind this - just not knowing what you might hit?

Yes. Unfortunately I'm so anal about these things that if I had to blind fix I'd spend ages measuring up so that all the concrete screws went dead centre into a full brick, not into a joint or splitting off the edge of a brick etc.