Compacfoam or Pultruded Fibreglass angle for sliding window support

[gravelrash]

I see the general consensus for heavy doors over insulated cavity is CompacFoam inset and bolted through to floor slab. This seems a good option but wondering if anyone has used fibreglass angle or box section to solve the same issue.

[gravelrash]

bump

[Olf]

In a similar thread Purenit and Marmox were mentioned