100mm loft roll insulation
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Product Details
100mm loft roll insulation is a mineral wool product supplied in rolls, designed for easy installation between loft joists to improve thermal efficiency in your home. This thickness is typically used as the first layer of insulation, fitting snugly between joists to reduce heat loss and lower energy bills. The rolls are lightweight, flexible, and often come with pre-cut perforations, making them simple to trim to the required width. Commonly used in lofts and attics, this insulation also helps with sound reduction and is non-combustible for added safety. Alternative names like Knauf Insulation Loft Roll 44 or Rockwool Twinroll refer to different brands or specific product lines, but all serve the same purpose as a base layer for loft insulation projects
As of August 2026, PriceNailer data confirms that the cheapest price for 100mm loft roll insulation is £23.38 from BuilderDepot across 11 suppliers. Prices have increased by 27.5% over the last 17 months.
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Frequently Asked Questions
What coverage area does 100mm loft roll insulation provide per pack?
Coverage varies by brand, but typically a pack covers 6-8 square metres. Check the product specifications as roll width and length vary between manufacturers, with common widths being 370mm or 400mm to fit standard joist spacings.
Is 100mm loft insulation thick enough on its own?
100mm is usually used as the first layer between joists, but current building regulations recommend 270mm total thickness. You'll typically need to add a second layer of 170mm insulation laid perpendicular to achieve optimal thermal performance.
What's the difference between glass wool and rock wool 100mm loft rolls?
Both provide similar thermal performance, but rock wool offers slightly better fire resistance and acoustic properties. Glass wool is typically more affordable and easier to handle, while rock wool is more durable and moisture-resistant.
Do I need protective equipment when installing 100mm loft roll insulation?
Yes, always wear gloves, long sleeves, eye protection, and a dust mask when handling mineral wool insulation. The fibres can irritate skin and respiratory system, so proper PPE is essential for safe installation.
Can 100mm loft roll insulation be compressed to fit tight spaces?
Light compression is acceptable, but avoid over-compressing as this reduces thermal performance significantly. If joists are narrower than the roll width, trim the insulation rather than forcing it into place to maintain its insulating properties.