RockPrime Blown Loft Insulation

Suitable for installation between and over ties/ joists in domestic, commercial and industrial buildings, offering excellent thermal, acoustic and fire performance.

Lightweight, water repellent, rot proof stone wool loft insulation, installed by blowing, in accordance with BS 5803-2, by a Rockwool trained installer. Rapid installation method creates minimum disturbance to occupants.

Non-combustible, achieving a classification of A1 in accordance with BS EN 13501-1.

Rockwool insulation products do not contain blowing agents with an ozone depletion potential (ODP) or global warming potential (GWP), are CFC-HCFC-HFC free and 97% recyclable. They will not react with metal components or cause loss of plasticiser from PVC cables and pipes.

General information

Uniclass 2015

Pr_25_31_48_48 Loose-fill mineral wool fibre insulationPrimary


P10/10 Loft insulation

P10/150 Blown loft insulation

Specification data - Loose-fill mineral wool fibre insulation

Product Reference

RockPrime Blown Loft Insulation


150 mm

170 mm

210 mm

270 mm

330 mm

420 mm

Standard product features

Blown density (nominal):

21 kg/m³.

Thermal conductivity at 10ºC mean temperature:

0.045 W/mK.

U value:

Based on a construction of tiles/ slates on 30º pitch roof, with sarking felt and ventilated loft space. Insulation, supported by plasterboard ceiling, is applied over 100 mm deep ceiling joists at 600 mm centres.

  • 150 mm depth: 0.28 W/m²K.
  • 170 mm depth: 0.25 W/m²K.
  • 210 mm depth: 0.20 W/m²K.
  • 270 mm depth: 0.16 W/m²K.
  • 330 mm depth: 0.13 W/m²K.
  • 420 mm depth: 0.10 W/m²K.

Third party certifications
  • KM 33106. : In accordance with BS 5803: Part 2 (Thermal insulation, pitched roof spaces in dwellings – pelleted or granular).
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