Loft Insulation

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What is loft insulation?

Loft insulation is any material installed within the joists of a pitched roof space to reduce heat loss from the building below.

We offer a range of ISOVER products suitable for installation in a loft.

Glass mineral wool is a flexible solution that is easy to fit within the loft with the main point of attention when installing being at the eaves to ensure no roof ventilation is blocked. It is common to see anything upwards of 300mm of glass mineral wool insulation laid at ceiling level to meet the current thermal performance regulations.

Some old loft insulation installations can easily feature as little as a single layer of around 100mm insulation between the ceiling joists. The most common solution to top-up existing loft insulation levels is to lay glass mineral wool insulation over the top of the existing insulation within the ceiling joists, although if this is in particularly poor condition it may be better to replace this with fresh material.

It may be the case that the loft area is to be used for storage, and if so then the loads that the roof construction will be subjected to should be taken into careful consideration. Advice should be sought on correct installation practices, including ensuring a well-sealed ceiling below the loft joists. Continuity of insulation at the wall/roof junction should be achieved without blocking eaves vents and while ensuring adequate ventilation of the loft space.

Key Considerations

When using ISOVER products, you need to satisfy yourself that use of the product meets all relevant national Building Regulations and guidance as well as local, national and other applicable standards relevant for your construction or application, including requirements in relation to fire and applicable height restrictions. In addition to the product datasheet, please refer to the following product documents:

The building detail is for illustrative purposes only. It does not constitute advice and should not be relied upon.

Insulation products
Product Name Thickness Range Sizes Lambda
Isover Spacesaver 100-200mm Width 1.16m, Length 5.2 - 12.18m 0.044
Isover Spacesaver Lite 100-200mm Width 1.16m, Length 3.5 - 7m 0.044
Isover Spacesaver Plus 100-200mm Width 1.16mm, Length 3.5 – 7m 0.040
Isover Spacesaver Ready-Cut 100-200mm Width 3 x 0.386m or 2 x 5.8m, Length 5.2 - 12.18m 0.044