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 and news
Gregor Harvie argues that AI is state-sanctioned theft of IP.
Many resources for visitors aswell as new features for members.
Using technology to empower communities
The Community data platform; capturing the DNA of a place and fostering participation, for better design.
Heat pump and wind turbine sound calculations for PDRs
MCS publish updated sound calculation standards for permitted development installations.
Homes England creates largest housing-led site in the North
Successful, 34 hectare land acquisition with the residential allocation now completed.
Scottish apprenticeship training proposals
General support although better accountability and transparency is sought.
The history of building regulations
A story of belated action in response to crisis.
Moisture, fire safety and emerging trends in living walls
How wet is your wall?
Current policy explained and newly published consultation by the UK and Welsh Governments.
British architecture 1919–39. Book review.
Conservation of listed prefabs in Moseley.
Energy industry calls for urgent reform.
Heritage staff wellbeing at work survey.
A five minute introduction.
50th Golden anniversary ECA Edmundson apprentice award
Showcasing the very best electrotechnical and engineering services for half a century.
Welsh government consults on HRBs and reg changes
Seeking feedback on a new regulatory regime and a broad range of issues.
CIOB Client Guide (2nd edition) March 2025
Free download covering statutory dutyholder roles under the Building Safety Act and much more.