Cold roof
A cold roof is roof in which the thermal insulation layer is located immediately above or between the ceiling joists meaning that everything above the insulation, such as the rafters, and any roof space, will be colder than the living space below it.
When warm, damp air permeates up through the ceiling and reaches the cold roof space, the change in temperature can result in condensation forming. Adequate roof space ventilation must be provided therefore to remove this air. This requirement, and the need for preventative measures to tackle cold bridging, means that warm roofs can be preferable.
A warm roof is one in which the insulation layer is laid on top of roof structure (or above the loft or attic space in the case of pitched roofs) so that the roof structure or roof space is closer to the inside temperature and so the risk of condensation is reduced.
Particular care must be taken when installing loft insulation, as this can convert a pitched roof from a warm to a cold roof. Ventilation must then be provided to prevent the accumulation of moist air and so condensation, as this can cause the roof structure to deteriorate and ultimately to fail.
[edit] Related articles on Designing Buildings
Featured articles and news
A case study and a warning to would-be developers
Creating four dwellings... after half a century of doing this job, why, oh why, is it so difficult?
Reform of the fire engineering profession
Fire Engineers Advisory Panel: Authoritative Statement, reactions and next steps.
Restoration and renewal of the Palace of Westminster
A complex project of cultural significance from full decant to EMI, opportunities and a potential a way forward.
Apprenticeships and the responsibility we share
Perspectives from the CIOB President as National Apprentice Week comes to a close.
The first line of defence against rain, wind and snow.
Building Safety recap January, 2026
What we missed at the end of last year, and at the start of this...
National Apprenticeship Week 2026, 9-15 Feb
Shining a light on the positive impacts for businesses, their apprentices and the wider economy alike.
Applications and benefits of acoustic flooring
From commercial to retail.
From solid to sprung and ribbed to raised.
Strengthening industry collaboration in Hong Kong
Hong Kong Institute of Construction and The Chartered Institute of Building sign Memorandum of Understanding.
A detailed description from the experts at Cornish Lime.
IHBC planning for growth with corporate plan development
Grow with the Institute by volunteering and CP25 consultation.
Connecting ambition and action for designers and specifiers.
Electrical skills gap deepens as apprenticeship starts fall despite surging demand says ECA.
Built environment bodies deepen joint action on EDI
B.E.Inclusive initiative agree next phase of joint equity, diversity and inclusion (EDI) action plan.
Recognising culture as key to sustainable economic growth
Creative UK Provocation paper: Culture as Growth Infrastructure.