EPS70 insulation

[akist]

I have excess EPS70 Kay Metzeler 120mm insulation, could I use it in between joists in a flat roof instead of rigid?

 

[noseall]

I have excess EPS70 Kay Metzeler 120mm insulation, could I use it in between joists in a flat roof instead of rigid?

Between? Are you venting the roof or putting additional insulation across the top of the joists?

 

[robinbanks]

Are you drawing a distinction between 120mm EPS board and rigid board? What do you mean by "rigid"?

 

[akist]

Are you drawing a distinction between 120mm EPS board and rigid board? What do you mean by "rigid"?

Yes, PIR ("rigid") boards have better thermal parameters.

But I was asking if the EPS70 would be appropriate in the flat roof joists for other reasons, as it is made for floors and walls.

Between? Are you venting the roof or putting additional insulation across the top of the joists?

It is a cold flat roof, a one story side extension attached to the side of the house below the gables.

The layers are:
"3 layer torch on system with mineral finish"
18mm ply
firrings
150mm joists

There are soffit vents on all 3 sides of this roof for ventilation and due to the firrings many gaps above the joists as well.

 

[robinbanks]

Yes, PIR ("rigid") boards have better thermal parameters

Rigidity, to me, is not about thermal performance; it's about structure. I regard EPS boards as "rigid", in contrast to e.g. blown EPS bead which is not rigid..

You can use EPS board in a roof

 

[akist]

Thanks, will do, I have tons of it left.