Loft and Roof Insulation in Jersey

What the job involves

For a standard loft, the work involves laying insulation between and over the ceiling joists to the recommended depth, while making sure eaves ventilation gaps are kept clear so the roof structure can still breathe. We also check for any existing damp or timber issues before insulating over them, since insulation can mask problems if they're not dealt with first.

Where a roof is being re-covered or converted, we fit rigid PIR board between and often below the rafters, combined with a vapour control layer to prevent moisture from warm internal air condensing within the roof structure. This approach suits rooms in the roof and vaulted ceilings where joist-level insulation isn't practical.

On re-roofing projects we sometimes combine mineral wool at joist level in cold roof areas with PIR at rafter level in habitable roof rooms, tailoring the specification to how each part of the roof is used.

Common problems we fix

Poor or outdated insulation causes a specific set of issues we see repeatedly in Jersey lofts.

• Old, thin or disturbed loft insulation no longer meeting current recommended depths
• Condensation and mould forming where warm moist air meets cold roof timbers
• Blocked eaves ventilation from insulation pushed too far into the eaves
• Cold spots and draughts in converted loft rooms with inadequate rafter insulation
• Insulation compressed or displaced by storage boarding laid directly on top
• Damp timber discovered under old insulation that had been trapping moisture
• Heat loss through poorly insulated hatch covers and loft access points
• Missing insulation around water tanks and pipework leading to freezing risk in cold snaps

Materials and standards we use

We fit mineral wool insulation at joist level in standard cold lofts, since it's cost-effective, non-combustible and easy to top up in stages, and rigid PIR insulation board at rafter level or in warm roof constructions, where its higher performance per millimetre suits the tighter space available in a room in the roof.

All insulation work is carried out with proper attention to ventilation, since trapping moisture in an unventilated roof void causes more problems than it solves. Where insulation work forms part of a re-roofing project, the roof covering itself is completed to BS 5534.

How much does it cost in Jersey

Loft insulation cost depends largely on the size and shape of the loft, whether it's a simple open space or broken up by water tanks, hip ends and awkward access. A straightforward top-up job in an accessible loft is generally quicker and less costly than a full rafter-level insulation scheme in a converted roof room.

Access again plays a part, particularly for rafter insulation carried out alongside a re-roof where scaffolding is already in place versus doing it as a standalone internal job. Material choice between mineral wool and PIR affects price, as does freight to the island for specific insulation products, and any requirements for listed or registered buildings around altering roof structures.

We give every customer a free, written quote so the scope of insulation work and the reasoning behind the specification are clear from the outset.