Insulating your loft is a quick and relatively inexpensive way to keep warm air in and lower your heating bills. But there’s a little more to it than meets the eye, and even if you already have some insulation it may not be working as hard as it could.
We all know that warm air rises, and in a home with no insulation around 25% of the heat you pay for will be lost through the roof. A layer of insulation applied between the rafters of your roof or above the ceiling of the first floor is a really effective way to prevent waste and keep bills low. And according to the Energy Saving Trust, it’ll keep on saving you money for at least 40 years.
“If everyone in the UK installed 270mm loft insulation, we could save nearly £500 million – and 2.7 million tonnes of carbon dioxide every year, the equivalent of taking nearly 100,000 cars off the road.”
The Energy Saving Trust
Adding up the benefits
So, how much could you save? It depends whether you have any insulation currently, and whether existing insulation could benefit from another layer to bring it up to current building standards. If you’re using rolls of mineral wool – one of the most common insulating materials – the recommended depth of insulation is 270mm, although different materials need different depths to give the same performance.
We’ve based the estimates below on insulating a gas-heated, semi-detached home with three bedrooms. To find out more about how much you could save, just give us a call.
| Fitting an uninsulated home with 270mm insulation | Adding to existing 100mm of insulation to bring it to 270mm | |
|---|---|---|
| Installation costs | £100 – £350 | £100 – £350 |
| Approximate savings per year | Up to £175 | ~ £25 |
| Payback | < 2 years | > 4 years |
| CO2 savings per year | ~ 720kg | ~ 110kg |
Choosing the right type of insulation
If your loft is easy to access and free from any problems with damp or condensation, laying the insulation should be really straightforward. If the joists in your roof are regularly spaced, we’d recommend a low-density glass mineral wool quilt. We use two layers, the first lying snugly between the joists and the second at a right angle over the top. This brings the insulation of to the required depth for current Building Regulation standards.
Another option is loose-fill insulation such as vermiculite, mineral wool or cellulose fibre. This can then be poured between the joists to the right depth, meaning it’s great for irregular-shaped lofts or joists that are the wrong distance apart for rolls of insulation.
Getting more from your loft
If you’re planning on using your loft for storage, we can lay boards over the joists too. A single layer of insulation between the joists and under the boards won’t be enough, so we’d recommend laying rigid insulation boards on top, with wooden boarding on top of that.
If you’re planning to use your loft as an extra room we’d recommend fitting insulation board between the roof rafters instead – give us a call to find out more.
A word about damp…
Insulating between the joists of your loft will keep your house warmer, but it’ll also make the roof space above colder. So if you have any existing problems with damp or condensation, loft insulation could make them worse. We’ll look out for this during our site survey and advise you whether it’s best to fix the damp problems first.