Can I insulate my sloping ceiling?

If you have a loft, it is easy to insulate the joists or the rafters. It is something you can even DIY if you want to. Often however, people have a sloping ceiling, with no loft space at all. This makes insulation a lot more tricky, and indeed expensive, but if you want to bring your home up to standard, then it leaves you with little option.

Is my sloping ceiling insulated?

If you have a loft, you can simply take a look for yourself and see what insulation is there. If you have a plastered sloping ceiling it is much more tricky. The first thing you can do is to consider the build age and any renovation works that have taken place. Most properties built in the 70’s or earlier will not have any insulation in the roof. Anything built or renovated after 1980 may well have some insulation, but it is not until the last 20 years that you can be fairly sure that the sloping roof is insulated.

If this is all unclear, you will have to drill a hole in the ceiling and take a look with a boroscope.

How can you insulate a sloping ceiling?

If you want to insulate the roof, the first step will be to strip away the plaster and reveal the supporting beams underneath – usually wood. Your installer will then attach insulation board to the batons and then add new plasterboard. This whole process is obviously fairly extensive, and will cost around £40-60 per square meter. The process is very similar to adding internal wall insulation to a timber frame property.

Is it worth insulating a sloping roof?

Although the cost of insulating a sloping roof is fairly high (you are probably looking at several thousand pounds for a whole house with this type of roof), the savings will be great. Chances are the roof has little insulation, and the savings are going to be big – £300 a year would be a good estimate for the average house. That means payback in 10-15 years – not too bad when you put it into the context of other big home improvement works.

Loss of height with insulation?

One thing you will have to bear in mind when insulating a sloping roof is that extra layer of insulation is going to reduce the room height somewhat. Now if your roof is high or this is not an issue for you, then it probably won’t take much thought, but if reducing the height by 10cm or so would be a problem, then your options are more limited.

Alternatives to full insulation

If full insulation is a bit too expensive for you, or you don’t want to lose room height, you could look at using a thermal liner to insulate the ceiling. This is a 4mm thick insulating wallpaper effectively, which helps keep the ceiling from losing heat. It is not going to be as effective as 75mm Celotex, but it will help reduce issues like condensation, and offer some help in terms of heat loss. The cost of the materials are around £7 per square meter, and you can either install it yourself or get in your own installer.

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