Condensation and thermal performance in roofs
What it looks like
Inadequate ventilation or incorrectly installed insulation can lead to condensation issues within the roof space.
Why it happens
Roofs must incorporate suitable measures to prevent condensation and achieve adequate thermal performance. Designs should mitigate risks associated with both interstitial and surface condensation to ensure the long-term durability of the roof structure and maintain internal air quality.
What it costs if it is missed
Roofs must incorporate suitable measures to prevent condensation and achieve adequate thermal performance. Designs should mitigate risks associated with both interstitial and surface condensation to ensure the long-term durability of the roof structure and maintain internal air quality.
How to inspect for it
Verify that the specified insulation and ventilation provisions are installed as per the design to address condensation and thermal bridging.
How to prevent it
Roofs must incorporate suitable measures to prevent condensation and achieve adequate thermal performance. Designs should mitigate risks associated with both interstitial and surface condensation to ensure the long-term durability of the roof structure and maintain internal air quality.
Basis in regulation
BS 5250
Read the source
Last updated 23 August 2026. This is our editorial summary of publicly available regulation and site practice, not building control approval or a warranty determination.