Loft Insulation
Loft insulation is a relatively straightforward measure to install and can save around 30% of the heat loss from your home, and as much as 20% can be saved from your heating bills as a result.
This equates to £80 – £300 a year on your heating bills. Loft insulation helps to create an even temperature in your home – keeping your home warm in winter and cool in the summer.
Types of Loft Insulation Materials
There are several different types of materials which are commonly used:
- Mineral wool (Quilt or blown)
- Sheep’s wool
- Polyester fibre or expanded polystyrene
- Recycled paper, cellulose or fabric
- Hemp
Providing materials are installed professionally, then they all perform similarly, help to keep your home warm and reduce fuel bills.
Standards for Loft Insulation
Standards for loft insulation have increased since it was first introduced. In 1977 under the first building regulations standards, 25mm (1 inch) was recommended. Current building regulations now recommend 300mm (12 inches) or more, installed into modern new build homes.
How is Loft Insulation Installed?
Loft insulation is laid between and then over the ceiling joists in the loft. The material used is a very poor conductor of heat, so when warm air rises it is trapped underneath the layer of insulation and prevented from escaping through the roof.
The insulation is not laid underneath cold-water tanks, so some heat can escape up under the tank to reduce the risk of the tank freezing in winter. The cold-water tanks are also insulated with jackets, as is any associated pipe work in the roof space, that would not be covered by the loft insulation itself.
Ventilation should be maintained in the loft, this should be done by not laying the insulation right up to the eaves and abutting the roof felt. This may mean that closer to the eaves where the roof level is lower, the loft insulation thickness is reduced to allow a gap (50-100mm) to be maintained for air flow.
The back of the hatch should be insulated with a phenolic (Kingspan, Celotex etc) board ideally and the frame of the hatch should be draughtproofed to stop heat loss further and prevent as much moisture entering the loft, which could condense.
Do not use polystyrene to insulate the back of the hatch as it can give off a gas that can react with the plastic casing around electrical wires, causing degradation.
It may be necessary in some cases for additional ventilation to be installed, if there is a risk of condensation, or if it becomes a problem. Ask the installer for their advice.
Considerations for Loft Storage
Think about what you need to store in your loft space, you will not be able to re-board a loft on top of the existing joists in the same way, once it has 270-300mm of insulation, as this will sit around 130-180mm above standard joist level.
Attempts to squash it down into a 100-200mm gap can put pressure on your ceilings or make the insulation ineffective as it will lose its ability to trap sufficient air.
You can leave a small area of boarding down in the loft and tell the installers not to insulate over that area, or increase the level of your existing joists by cross laying 6” x 2” timbers on top, or invest in a bespoke loft flooring system if storage is essential.
You could simply have a good clear out and reduce your loft storage needs!
There may be grants available to help have the insulation professionally installed, or you may choose to do the work yourself by purchasing the products from an online supplier or DIY store.
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