Loft Insulation

About

Loft insulation is a thermal barrier installed in the roof space of a building to reduce heat loss through the ceiling. An uninsulated loft can account for around a quarter of a home's total heat loss, making it one of the most impactful areas to address when improving a property's energy performance. Installed correctly, loft insulation reduces heating costs, helps maintain a stable indoor temperature year-round and can contribute positively to a property's EPC rating. The right type of loft insulation depends on how the space is used. In a cold loft, where the roof space is unoccupied, insulation is laid at ceiling joist level. The current recommended depth for mineral wool is 270mm, typically achieved in two layers: 100mm between the joists, with a further 170mm across the top at right angles. Many older properties can be topped up to this depth without any structural work, though care should be taken not to push insulation into the eaves, as this restricts airflow and can lead to condensation in the roof space. In a warm loft or loft conversion, insulation is fitted between and under the rafters instead, with the required thickness determined by rafter depth and the target U-value for the build. Once you've insulated to 270mm, boarding over it needs a bit of care. That depth is deeper than most ceiling joists, so laying boards flat across them compresses the insulation underneath and undoes some of the benefit. Our loft boards range covers both raised loft boarding on loft legs and insulated loft deck options that keep the insulation at its full working depth. Types of Loft Insulation Loft Roll Insulation Mineral wool roll is the standard choice for insulating at joist level in a cold loft, available in a range of thicknesses from 100mm to 200mm from Knauf, Superglass and Isover. Between Rafter Insulation Mineral wool slabs, phenolic boards and PIR strips for loft conversions and warm roof applications where insulation sits within the roof structure rather than