Loft Insulation
Loft insulation normally refers to insulation that is required in a cold roofs, that is insulation installed horizontally between and on top of roof or ceiling beams, not insulation installed between and on top of the roof structure and rafters (a warm roof).
In a cold roof the air space above the ceiling joists is ventilated and therefore cold, without insulation between it and the warm house below there is significant risk of the warm moist air from the living spaces rising and then cooling quickly on the cold surfaces of the roof space and condensing. This can introduce moisture on the surfaces of the roof structure which can in turn lead to mould, and decay over long periods.
Introducing one or more layers of insulation between these spaces reduces heat loss and reduces the risks of condensation, preventing warm moist air from entering directly into the loft space.
The first building regulations on home insulation were issued in 1965 and required just 28mm of insulation for a loft, today this is recommended as at least 250 up to 300mm.
[edit] Related articles on Designing Buildings
- Approved Document F.
- Cold bridge.
- Condensation pipework.
- Damp.
- Damp proofing.
- Dehumidification.
- Designing out unintended consequences when applying solid wall insulation FB 79.
- Dew point.
- Diagnosing the causes of dampness (GR 5 revised).
- Dry-bulb temperature.
- Electrical resistance meters.
- Flashing.
- Humidification.
- Humidity.
- Hygrothermal.
- Interstitial condensation.
- Methodology for moisture investigations in traditional buildings.
- Moisture.
- Moisture content.
- Mould growth.
- Penetrating damp.
- Psychometric chart.
- Rising damp.
- Sling psychrometer.
- Spalling.
- Treating brickwork with sealant or water repellent.
- Water vapour.
- Wet-bulb temperature.
- Blue roof.
- Condensation in buildings.
- Domestic roofs.
- Flat roof.
- Flat roof defects.
- Interstitial condensation.
- Inverted roof.
- Roofing defects.
- Thermal bridging in buildings.
- Thermal comfort.
- Warm roof.
- Cold roof
Featured articles
Check out some of the best features and news from Designing Buildings as well as key stories from around the web.
Recognition, influence and growth
SocEnv identifies three strategic pillars in new strategy to 2045.
Discover the future of roofing, cladding and insulation.
New guidance for professional practice, cultural change and regulation in social housing.
The heritage of nuclear and conventional power stations.
New measures to stop people being ripped off
Government to protect families from cowboy builders and aggressive bailiffs.
New Futurebuild showcase brings an innovation-first approach.
National Planning Policy Framework
Understanding the 2026 changes.
ECA's public affairs priorities
Member consultation opens to shape priorities for 2027 to 2030.
Dutyholder responsibilities from 1 July 2026.
Where performance meets practice
The Building Envelope Stage at UKCW Birmingham.
CIAT publishes briefing on planning reforms.
Leaders in Learning for Practice Network
Call for conservation leaders in learning to register interest in new network.