Case study
Loft Insulation Case Study — Full Loft Upgrade From Bare Joists to an Insulated Roof Envelope, Manchester
This loft was taken from bare joists to a full insulated envelope — 300mm Knauf across the floor, SF19 SuperFOIL across the 50m² roof pitch and a 6m² raised walkway for safe access.
What we found
- •Large sections of the loft floor had exposed joists and little effective insulation
- •A narrow central board was the only safe route through the roof space
- •The blockwork gable and roof pitch were completely uninsulated
- •The long symmetrical roof space created a large area for heat to escape
The problem
The loft was inspected as part of a full assessment of the roof space. It was largely exposed, with bare joists at ceiling level and no insulation across the roof pitch.
The loft survey showed exposed joists across most of the floor and no insulation across the roof pitch. There was no boarded route through the space, so access for the work had to be established first.
Our assessment
The loft floor measured approximately 39m² and the roof pitch measured approximately 50m². We recommended a complete upgrade using 300mm Knauf glass mineral wool across the floor, SF19 SuperFOIL across both roof slopes and a 6m² raised central walkway to preserve access.
The installation
The joist bays were cleaned before a 100mm base layer of Knauf mineral wool was installed between the timbers. A further 200mm was cross-laid to create full coverage and reduce thermal bridging.
A raised walkway was fitted above the insulation so the central route could remain usable without compressing the wool.
The SF19 SuperFOIL system was installed from the eaves to the ridge on both sides. Joints were overlapped and taped, the blockwork gable junction was finished neatly and ventilation routes were kept open.
The result
The loft changed from a largely exposed roof space into a fully insulated area with a safe central route. The floor, roof pitch and access route were completed as a single continuous system.
The installation helped to
- Installed 300mm insulation across a previously exposed floor
- Added a continuous SuperFOIL roof-pitch layer
- Created a raised central walkway
- Reduced heat loss across a large roof space
- Improved comfort in the bedrooms and landing
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