Loft Insulation Specialists across the North West.

A poorly insulated loft is the single easiest heat loss to fix on a typical UK semi or detached house. Heat rises, and if there is less than 270mm of mineral wool between the ceiling joists and the cold air above it, you are heating the street as much as the house. Building Regs Part L sets 270mm as the minimum for new work; EcoFlex recommend 400mm for optimal thermal performance. Most pre-2000 houses in the L, CH, LL and WA postcode areas are sitting on 100mm or less.

We fit glass mineral wool (Isover or Knauf), rigid PIR board (Kingspan TP10 or Recticel Eurothane), or a combination of both depending on the loft type. Cold lofts, warm lofts, cut-rafter roofs, and trussed-rafter roofs all have different requirements. We assess which is appropriate before quoting.

What we fit and why

For a standard cold loft on a trussed-rafter roof, the spec is two layers of Isover or Knauf glass mineral wool: 100mm between the joists and 170mm across the top at 90 degrees, giving the 270mm minimum. Rolling the second layer at right angles avoids the thermal bridging that single-layer installs let through at the joist position.

For warm loft conversions where the insulation goes between and below the rafters, we fit Kingspan TP10 or Recticel Eurothane rigid PIR board. PIR achieves a lower U-value per millimetre than mineral wool, which matters when rafter depth is limited. On a 100mm rafter, 90mm PIR between and 50mm PIR below achieves Part L compliance; the same performance with mineral wool is not physically possible in that depth.

Ventilation and vapour control

Cold-loft insulation must leave a minimum 50mm clear airspace between the top of the insulation and the underside of the roof covering to allow air movement. This is not optional; without it, condensation builds on the cold timber and you trade heat loss for a rot problem. We check the eaves ventilation before laying and advise on any remedial ventilation work needed.

Warm-rafter insulation requires a vapour control layer on the warm side of the insulation to stop interstitial condensation forming within the rafter depth. We install Intello or Pro Clima VCL taped at all joints and laps. This is frequently missed on retrofit installations and is the cause of most premature degradation in warm-rafter insulation systems.

What it costs

Cold loft insulation at 270mm on a standard three-bedroom semi typically runs between £400 and £700 plus VAT, including clearing and reinstating loft boards where access is needed. Warm rafter insulation as part of a loft conversion scope is included in the conversion quote. Standalone warm rafter retrofits are quoted on survey as they depend heavily on rafter depth, roof area and access.

What we back it with

All insulation work carries a 5-year workmanship guarantee. Mineral wool is guaranteed inert for 50 years by Isover and Knauf. PIR board carries a 25-year thermal performance guarantee from Kingspan. We also provide a Part L compliance certificate for any insulation that forms part of a building regulations submission.