Warm roof vs cold roof

This is general information, not a survey, design, legal or Building Control decision. The correct scope and standard depend on the property, work, date and regulatory route.

In a warm roof, insulation is generally above the structural deck or between/over rafters so the structure sits closer to the warm side. A cold roof places insulation below the deck and needs carefully designed ventilation and vapour control.

A replacement or new extension roof should be designed as a complete build-up. Do not transfer a detail from an existing roof to a new element: the assessment, condensation risk and current regulatory route matter.