150mm loft roll insulation
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Product Details
150mm loft roll insulation is a flexible glass wool roll designed for fitting between loft joists to trap heat and cut energy bills in home improvement projects. It comes in widths that match standard joist spacing, often as combi-cut rolls for easy unrolling without measuring or cutting tools in most cases. Lay it snugly between joists starting from the eaves and furthest from the hatch, then add a second layer over the top at 90 degrees for total depths like 270mm to meet regulations. Avoid compressing it, and cut to fit around pipes or cables using a utility knife while wearing protective gear. Ideal for topping up existing insulation or new lofts to make your home warmer and more efficient.
As of August 2026, PriceNailer data confirms that the cheapest price for 150mm loft roll insulation is £38.36 from Insulation UK across 5 suppliers. Prices have decreased by 4.3% over the last 4 months.
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Frequently Asked Questions
What coverage area does 150mm loft roll insulation provide?
Coverage varies by roll width and length, but typically a standard 8.3m² roll will cover around 37 square metres when laid between 400mm joist centres. Always check the manufacturer's specifications as pack sizes differ between brands and suppliers.
Can I lay 150mm loft roll insulation directly over existing insulation?
Yes, 150mm loft roll can be laid perpendicular over existing insulation to increase thermal performance. Ensure the existing insulation is dry and in good condition, and avoid compressing the lower layer which reduces its effectiveness.
What width options are available for 150mm loft roll insulation?
150mm loft roll insulation typically comes in 370mm and 570mm widths to fit standard UK joist spacings of 400mm and 600mm centres respectively. Some manufacturers offer combi-cut rolls that can be split to suit both spacing requirements.
Do I need a vapour barrier with 150mm loft roll insulation?
Most modern 150mm loft rolls don't require a separate vapour barrier as they're designed to be breathable. However, ensure adequate ventilation in the loft space to prevent condensation issues and check building regulations for specific requirements in your area.
What R-value does 150mm loft roll insulation achieve?
150mm loft roll insulation typically provides an R-value of around 3.75 m²K/W, depending on the manufacturer and thermal conductivity. This contributes significantly to meeting current building regulations when combined with additional layers for total depths of 270mm or more.