Wall Insulation
The stud depth is fixed, so a 90 mm frame sets a hard limit on the batt that fits. HP and HD grades pack a higher R-value into the same cavity by density rather than thickness.
R2.0 to R2.7 covers most external walls at 90 mm. Where the number has to go higher and the frame cannot change, rigid board is the way past it. Delivered across Victoria and New South Wales.