- Project plans
- Project activities
- Legislation and standards
- Industry context
Last edited 21 Nov 2017
A cold roof is roof in which the thermal insulation layer is located 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.
 Find out more
 Related articles on Designing Buildings Wiki
Featured articles and news
An artist finds ruined and decaying buildings a source of inspiration for his work. Book review.
When is there a right to light, and what happens if it is obstructed?
What would the nationalisation of economic infrastructure mean for GB?
A new guide to improving value by reducing design error.
We've reached 80,000 page views a day and 10,000 registered users. Why not join them?
A masterplan is a framework within which a location is encouraged to develop or change. Read our introductory article.
New consultation announced on a specialist Housing Court to settle landlord-tenant disputes.
ICE responds to a transport consultation advising the government to make decisions enabling more inclusive cities.
BRE and Loughborough University complete first phase refurbishment of demonstration home.
If you’re a great writer and have practical experience of the construction industry, it could be you.
Frustrated by long documents or technical jargon? Put off by sign-up forms or costs? Take this 5 min survey to help improve construction knowledge.