Loft Insulation Case Study — Compact Loft Insulation Upgrade Around a Hatch, Southampton

The problem

Tom asked us to improve the loft after noticing condensation on the bedroom windows and rapid heat loss overnight. The compact roof space was easy to access, but there was no effective insulation across the ceiling.

The exposed joists and uninsulated hatch area meant the upstairs rooms were directly affected by the cold roof space above.

Our assessment

The loft floor measured approximately 31m². We recommended a 300mm Knauf glass mineral wool system, using a 100mm layer between the joists and 200mm across the top. The compact layout required careful fitting around the hatch and low edge bays.

The installation

The joist bays were cleaned and the 100mm layer was cut to fit tightly around the hatch trimmers and timber supports. Narrow sections were used beneath the lower slopes to avoid leaving gaps.

The 200mm layer was then cross-laid across the loft, stopping neatly around the hatch opening. The ventilation route at the eaves was checked and left clear before the final inspection.

The result

The loft was left with a consistent 300mm insulation layer and a clear, usable hatch. Tom reported that the bedrooms held their temperature for longer and felt less cold first thing in the morning.