Loft Insulation Case Study — Narrow Loft Insulated Beside a Side Walkway, Oxford

The problem

Helen contacted us because two upstairs bedrooms felt cold along the external wall. The loft was narrow and awkward to move through, with a basic access strip along one side but little insulation across the main floor.

The restricted headroom had made previous improvement work difficult, and the edge areas had been left largely untreated. These were the same areas where the rooms below felt coldest.

Our assessment

The loft floor measured approximately 33m². We recommended a 300mm Knauf glass mineral wool system, retaining the side access boards and carefully insulating the low areas beneath the roof slopes. The installation consisted of 100mm between the joists and 200mm cross-laid above.

The installation

A temporary lighting setup was used so the team could work accurately in the low sections. The 100mm base layer was cut to fit between the joists, with smaller pieces used around braces and narrow edge bays.

The 200mm top layer was installed across the main floor at right angles to the joists. The existing side boards were kept clear, and the insulation was finished close to the eaves while preserving the ventilation gap.

The result

The loft gained full-depth insulation across the previously exposed floor area while retaining the existing side access route. Helen reported fewer cold spots in the upstairs rooms and better heat retention during the evening.