We signed with a timber frame supplier last week 😁. I asked the timber frame company about changing to a warm roof as their spec had no insulation in the small attic space above the horizontal ceiling of our "rooms in roof" attic. They have come back with this as an optional extra:
"To replace supply only 280mm quilt between bottom chord of top hat truss with 150mm loft roll insulation and supply only of 140mm PIR to slope of truss. No additional VC foil/service battens or
The attic area is a very small crawl space, but will be the likely site of the MVHR unit and otherwise is just for storage. Cost of this optional extra is nearly £2k extra, supply only....
I always said we wouldn't compromise on insulation and airtightness, but does this spec seem okay? Cost-wise I wondered whether to leave the 280mm quilt, and buy what we need separately, but would any heat actually reach the attic area with that level of insulation on the horizontal? 🤔