Isover Spacesaver Loft Roll is a low-density, glass mineral wool insulation roll supplied pre-perforated for thermal insulation at ceiling joist level in unheated domestic loft spaces.

It is primarily used for:

• Thermal Insulation at Loft Floor Level: Laying flat between and across ceiling joists in unheated attic spaces to stop heat rising from living quarters below, significantly lowering home heating costs.

• Top-Up Loft Insulation (Cross-Layering): Serving as a second cross-layered coat laid at a 90-degree angle over existing joist-level insulation to meet current UK Building Regulations recommended loft depths of 270mm - 300mm

• Quick Fitting Between Standard Joist Centers: Featuring pre-cut perforations at 2 x 570mm or 3  x 380mm widths, allowing rolls to be easily parted by hand to fit snugly between standard 400mm or 600mm ceiling joist centers without extensive cutting.

• Fire Resistance & Sound Attenuation: Achieving an Euroclass A1 non-combustible fire rating while absorbing airborne sound travelling between the roof space and living spaces below.

Available for collection from our Rugby branch or local delivery using our own fleet.

Timber products are typically delivered in one of our vans or pickup trucks. Delivery is kerbside and the final offloading position is always subject to safe access and the driver’s discretion.

Please tell us before delivery about:

• Narrow roads or restricted entrances
• Parked vehicles or limited turning space
• Overhead cables, trees or other obstructions
• Soft, sloping or unsuitable ground
• Any other access concerns

Enter your postcode on the product page to check your delivery area. We’ll confirm the delivery date after your order is placed.

What total depth of insulation do I need to meet UK Building Regulations?

Current UK Building Regulations recommend a total thickness of 270mm to 300mm of glass mineral wool at ceiling joist level. This is usually achieved by laying a 100mm layer between the joists and cross-layering a second 170mm or 200mm roll at a 90° angle over the joists to cover the timber tops and eliminate thermal bridging.

Can I lay loft roll directly over electrical cables and downlights?

• Cables: High-draw electrical cables (such as electric showers, cookers, or solar PV lines) should be lifted and laid on top of the insulation to prevent overheating. Low-power lighting cables can remain beneath, provided they are not tightly bunched.

• Downlights: Never cover recessed downlights directly with loft roll. Install fire-rated downlight protection covers (loft caps) over each fitting first to maintain safe airflow around the bulbs and prevent fire hazards.

Do I need to leave a ventilation gap at the eaves?

Yes. Always leave an unobstructed 50mm air gap between the edge of the insulation and the sloped roof sheet at the eaves (where the roof meets the external wall). Blocking this gap cuts off airflow through loft vents, leading to severe condensation, mould, and timber decay.

Should I cover the loft hatch with insulation?

Yes. Uninsulated loft hatches are a major source of heat loss and draft infiltration. Fix a cut piece of 100mm–150mm rigid insulation board or a piece of loft roll wrapped in plastic to the back of the loft hatch door, and fit draught-excluding foam tape around the frame perimeter.