100% NHBC Compliant
Maintains 270mm insulation & structural warranty
Squashing 270mm insulation down to 100mm joist height cuts its thermal efficiency by up to 60%, leading to skyrocketing winter heating bills and freezing upstairs bedrooms.
Without a 50mm ventilation gap, warm air rising from the house hits cold boards, condensating into water droplets that rot roof timbers and create toxic mould spores.
NHBC and Premier Guarantee new home warranties explicitly state that altering roof truss loads or compressing insulation voids your 10-year builder structural cover.