As bills rise, energy efficiency will be a priority for homeowners. Installing loft insulation at ceiling level is a quick and practical way to prevent heat loss, so Bradley Hirst, Technical Services Manager at Knauf Insulation, explains what you need to know to successfully insulate in this application.
Building regulations are changing
The minimum thermal performance standards set out in Approved Document L of the Building Regulations will change on 15 June 2022. After this date, the cold roof build-up of renovated roofs must achieve a U-value of at least 0.16W/m2K. This can typically be achieved by installing Knauf Insulation’s Loft Roll 44 at a minimum depth of 270mm or Loft Roll 40 at a minimum depth of 250mm – but for maximum performance we recommend installing insulation at a depth of 400mm.
Remember to layer insulation
Insulation must match the depth of the joist, so if the joist is 100mm deep your first layer of insulation should be too. The top layers should be fitted at right angles to the layer below, completely covering the joist.
Unwrap Mineral Wool insulation in the loft
We compress our Glass Mineral Wool so there’s more product per pack. But this means when you unwrap it, our Loft Roll insulation will expand up to 10 times its original thickness. So, unwrap it where you’re going to install it.
Get a good fit
Unintended air gaps reduce performance, so make sure rolls are butted together, friction fitted against joists and pushed down around the roof perimeter to meet insulation in the wall head.
Maintain ventilation
To prevent condensation, never cover air vents with insulation and if the roof is lined with sarking felt, allow for continuous ventilation of the roof void by leaving an air gap at the eaves.
Don’t cover cables
Reroute high voltage electrical cables over the top of the insulation to prevent the risk of overheating or fire. A benefit of Knauf Insulation Loft Roll is that it is non-combustible, so it will not contribute to the development or spread of fire should it occur.
For further information on Knauf Insulation visit https://www.knaufinsulation.co.uk/
