Fastening for 18mm OSB through 50mm kingspan?

[Live-round]

I'm putting 50mm pir insulation on top of a concrete slab then covering with 18mm OSB. I was going to use grab adhesive between the osb and kingspan.
Final floor covering will be vinyl. I'm worried about the floor flexing. How should I fasten the osb to the concrete.
If I use a long bit and drill through everything then I guess I won't be able to push a rawplug through the 7mm hole. Any ideas,?

 

[JP_]

I don't know, but maybe best to batten the floor (not even sure if that is the correct term!) with insulation between, and the boards screwed in to the wood.

 

[Live-round]

Good idea ..
But I haven't the space to increase the floor height. But I guess I could put battens down between the pir sheets.
Not easy ..

 

[JohnD]

you don't need battens.

 

[Live-round]

So what's your suggestion johnd,,?

 

[Mr Chibs]

What about bonding the pir to the concrete first, then bond the osb to pir. You won’t then need battens.

 

[Mr Chibs]

Expanding foam will stick the pir down, especially if you can weight it all down for 30 mins.

 

[JohnD]

So what's your suggestion johnd,,?

Floating floor.

 

[JohnD]

https://www.kingspan.com/gb/en-gb/p...ice/why-and-how-to-construct-a-floating-floor

 

[Deleted member 174758]

Floating floor.

Agreed! Normally you should lay a sheet of plastic on the concrete (to stop water uptake in the PIR), then lay the PIR boards over that (ideally tape the joints with foil tape), and finally lay the sub-floor boards on top of the PIR, glueing the tongues (with a D4 flooring adhesive, assuming ut has tongues) and pulling the boards together with straps or a flooring slide hammer. Personally I'd use P5 18mm t&g chipboard

If you bond stuff onto PIR you need to be very careful about what you use - solvent base adhesive can attack and damage the PIR insulation and might cause all sorts of problems such as cupping of boards, so don't be tempted to cut that particular corner

 

[Live-round]

Many thanks everyone....
I've a bit of a better undestanding of how to proceed..