Best Loft & Wall Insulation — 150mm (2026)
2 loft & wall insulation matching size “150mm”, hand-picked from UK Amazon listings.
Not sure which one to pick? Read our Best Loft & Wall Insulation UK (2026) guide.
This selection features a range of 150mm loft and wall insulation products available on Amazon UK. Achieving optimal thermal performance in older properties or when undertaking renovations often relies heavily on the correct R-value, and 150mm is a commonly specified depth for cavity walls and loft conversions. This particular size offers a good balance between insulating effectiveness and space constraints within your building structure. Ensure you accurately measure your loft or wall cavities before purchasing to guarantee a suitable fit, as incorrect sizing can significantly reduce the insulation's impact.
Choosing 150mm insulation is often driven by building regulations regarding thermal efficiency. It’s a frequently recommended depth for solid walls and a standard choice for loft installations where space allows. This product range includes various materials like mineral wool and PIR foam, each with distinct properties relating to their R-value and installation requirements – it's important to consider your specific needs when selecting.
Before purchasing, verify the product’s R-value against current building regulations for your property type and location. Confirm that the insulation is suitable for both loft and wall applications based on manufacturer specifications. Always prioritise a secure fit to prevent gaps compromising the intended thermal performance of the installation.
#1 Pick
Knauf Loft Insulation Roll Roof Lagging 100 150 170 200mm Thick Attic and Floors (150mm, Cream)- Mineral Wool
- 150mm
£44.99
Pros
- Glass mineral wool rolls pre-perforated to fit common joist spacing
- Non-combustible with ECOSE bio-based binder for lower odour
- Effective for both loft and floor lagging in one product
Cons
- Itchy to handle without gloves and a mask like most mineral wool
#2 Pick
Knauf Loft Insulation Roll Floor Roof Lagging (3, 150mm)- Mineral Wool
- 150mm
£129.99
Pros
- Bulk 3-roll pack covers a full loft in fewer deliveries
- Mineral wool construction gives solid thermal and acoustic performance
- Works for both roof lagging and suspended floor insulation
Cons
- Kerbside delivery only on bulky multi-roll packs
FAQ
What does 'R-value' mean?+
R-value measures a material’s resistance to heat flow – the higher the R-value, the better the insulation. It's expressed in metres squared per watt (m²·K/W) and is a key factor in determining how well your loft or walls will retain heat.
What type of loft insulation is 150mm suitable for?+
150mm mineral wool batts are generally suitable for most standard lofts, particularly those with plasterboard ceilings. However, ensure the loft access is adequate and that the depth suits your existing structure; consult a building professional if unsure.
Can I use 150mm insulation in external walls?+
While 150mm PIR (polyisocyanurate) foam boards might be suitable for external wall applications, mineral wool is generally not recommended due to its susceptibility to moisture. Check the manufacturer’s specification carefully.
How much does 150mm insulation cost?+
The price of 150mm loft and wall insulation varies significantly depending on the material (mineral wool vs PIR foam) and quantity purchased. Prices are typically displayed clearly on Amazon UK listings.
What tools do I need to install 150mm insulation?+
You’ll generally require a utility knife, tape measure, safety glasses, gloves, and possibly a staple gun or batt clips depending on the type of insulation you're using. Ensure you have appropriate loft access equipment.
Does 150mm insulation comply with building regulations?+
The R-value of 150mm insulation generally meets current UK building regulations for solid wall and loft installations, but always verify the specific requirements for your property’s location and construction type.
How do I calculate how much 150mm insulation I need?+
Measure the perimeter of your loft or wall cavity accurately. Then, multiply this by the height (150mm) to determine the volume in cubic metres. Finally, use the product’s R-value to estimate the required thickness based on desired thermal performance.
What is PIR insulation?+
PIR (polyisocyanurate) insulation is a closed-cell foam material that offers excellent thermal resistance and is often used in external wall applications. It's more resistant to moisture than mineral wool but can be slightly more expensive.
How does 150mm insulation compare to other thicknesses?+
150mm provides a good level of insulation, but thinner options (e.g., 60mm) will offer less thermal protection and thicker options (e.g., 240mm) may be impractical for many lofts or walls.
What if the insulation doesn't fit perfectly?+
Most manufacturers provide some tolerance in their dimensions, but it’s crucial to measure accurately before purchase. Minor gaps can often be filled with expanding foam sealant to maintain thermal continuity.