Fibreglass Insulation

What Is Fibreglass Insulation Used For?

Fibreglass insulation is suitable for a wide range of applications. Used for loft insulation, it's laid between or across joists to reduce heat loss through the roof. Knauf Loft Roll and Isover Spacesaver are popular choices here with Combi-Cut perforations that make it easy to cut to fit standard joist spacings without extra tools. Superglass Multi Roll is another reliable option, available in a range of thicknesses to suit different thermal targets. 

For acoustic insulation, glass wool air-pocketed structure makes it an effective sound absorber, reducing noise transmission between rooms and from neighbouring properties. Superglass Acoustic Roll and Knauf Acoustic roll are designed specifically for this, fitting between studs in partition walls and floors.

For cavity wall insulation, fibreglass batts pack out the gap between masonry skins, addressing one of the biggest sources of heat loss in older homes. Superglass Superwall Cavity Batts are designed for this application and supplied in convenient packs.

Why Choose Fibreglass Insulation?

Fibreglass insulation is non-combustible, achieving the highest possible Euroclass A1 fire rating for both safety and Building Regulations compliance. It's also resistant to mould and won't degrade over time when kept dry, making it a reliable long-term choice.

It's lightweight and straightforward to handle, which keeps installation quick whether you're a contractor or tackling a DIY project. Plus, it’s manufactured from recycled glass, making it a more sustainable option than many alternative materials.

One thing worth knowing: glass wool should be kept dry, as it loses its insulating properties if it gets wet. It can also cause skin irritation, so gloves and protective clothing are recommended when handling and cutting it.

Choosing the Right Thickness

Fibreglass insulation is available in thicknesses from 25mm up to 280mm, with thermal conductivity values ranging from 0.032 to 0.044 W/mK depending on the product. Thinner products (25mm–50mm) suit acoustic applications and partition walls where space is limited, while thicker options are more commonly specified for loft insulation to meet current Building Regulations targets.

If you're comparing brands, Knauf and Isover both offer products at 0.032–0.035 W/mK which puts them among the best thermal performance available in glass wool, while Superglass products span the full range depending on your application. 

If you're not sure which thickness or thermal performance you need, our team can talk you through it.

Why Choose Insulation UK for Fibreglass Insulation?

Genuine Superglass stockist: Full range of fibreglass insulation rolls and batts

All thicknesses available: From 25mm to 120mm

Competitive pricing: Trade rates and bulk pack savings available

Fast UK delivery: Next-day options available on most products

Expert technical support: Guidance on choosing the right thickness and thermal performance for your project

Suitable for lofts, walls, floors and cavities: One supplier for your whole project

Help and Advice: Not sure which fibreglass insulation is right for your project, or how much you need? Our team are on hand to help. Contact us here or call us on 0300 303 45 78.