How to tell if your loft is well insulated, for free!

20th January 2017

Winter has set in and gas and electric bills are going up, so you may be wondering if your home is as well insulated as it should be. Trying to keep as much heat inside your home is as important as ever in these colder months. Escaping heat from badly insulated houses can increase heating bills by up to £250 per year.*

So what does loft insulation do?

Generally speaking, loft insulation is placed in between the joists that make up your highest ceiling (or indeed, the loft floor). The insulation prevents heat from the home escaping into the loft. Assuming you don’t have a loft conversion, most homes do not have roof insulation between the rafters. This means that heat that escapes into the loft is lost through the roof.

How can I tell if I am losing heat through my roof?

There are a number of things you can do.

Firstly, on a cold day, where your home is much warmer than it is outside, go up into the loft. If the loft is very cold (close to the outside temperature) this is a sign that your home isn’t losing lots of heat into the loft. However, this is far from conclusive, as roofs are (or should be) well ventilated which will cool the loft space very quickly. A general rule of thumb would be, when it’s cold outside, if your loft is warm, you are losing a fair amount of heat from your home. If your loft is cold, you might not be losing lots of heat through the roof.

Another things to look at would be your existing loft insulation. If your loft insulation is like fiberglass matting, the recommended thickness is 270mm (approx. 11 inches). Some lofts can have as little as 25mm (1 inch) of insulation so it is certainly worth checking. If you want to add to your existing loft insulation, this can be done by a competent DIYer or a local Roofer can carry out the work. The cost will vary depending on how much additional insulation is required. If you are thinking of upgrading the insulation yourself, be aware of flat roofs, damp lofts or inaccessible loft spaces. Any of these should be assessed by a professional. We can assess this for you for free, and you can still do the insulation upgrade yourself if you want, just drop us an email and we’ll get something arranged for you.

In winter, you can often compare your roof to others nearby. This can sometimes provide some insight into how well your loft is retaining heat. On a frosty morning, have a look at your roof, the roof tiles will likely be covered in frost, this is perfect.

Work out which part of your roof will remain in the shade throughout the morning (this is vital).Pop out and have a look at your shaded area of roof every hour or so. Then look to your neighbours roofs and compare the mount of frost on each. The roofs you are comparing against must also be in a shaded area. The longer the frost stays on your roof, the better. So if the frost on your roof melts before everyone else’s, chances are, your loft insulation isn’t performing.


Comparable Roofs


The reason for this is that heat escaping from your home into the loft warms the roof tiles, and in turn melts the frost. If you are the first to lose the frost, it’s likely your loft is not well insulated, if you are among the last, it’s likely (but not certain) that your loft insulation is pretty good.

You could of course pay a surveyor or similar to come over with an infra-red camera and show you exactly where the heat is escaping your home. This is the most effective and accurate method, but also the most expensive. At between £175 and £250+ depending on the property, it’s a world away from checking yourself. But, if you aren’t confident or you have a flat roof / inaccessible loft spaces, this could be the option for you. Domestic Surveys can carry out this type of work for you in Bristol and the surrounding areas.

* Source – Jan 2017