External Wall Insulation U Values

Up to a quarter of all potential heat loss from your home can be attributed towards your walls. This particular type of heat loss is called ‘thermal bridging’ or ‘heat transmission’.

This is the natural process where warm air manufactured in your home travels towards the cold air outside, through your surrounding walls. Warm air will attempt to reach the cold by any means necessary; including via a window, door, roof space, and even your walls!

This is one reason why external wall insulation U values are of such interest amongst our customers and potential clients.

If you’re walls are uninsulated, they will not be very good at preventing this thermal transfer from happening. We are currently experiencing times where energy tariffs and prices are rising almost continually-with no clear end in sight!

For this reason you simply cannot afford to be unnecessarily losing any amount of heat from your home.

You could be metaphorically throwing pennies and pounds through the walls of your home all year round!

So external wall insulation is obviously a wise consideration – but what are the typical external wall insulation U values?

Do You Know What U Values are?

You may hear this phrase and unit of measurement (W/m²K) bandied about quite a bit within the construction industry.

It is a very common measurement, used to measure the insulating efficiency of certain elements within a property.

This provides a slight, but not definite, idea of how effective each element is at preventing heat transmission.

In very broad terms, a low U value indicates high insulating efficiency. So if it has a low number, generally speaking, it is very good at retaining heat.

The Average Wall U Value

It’s quite difficult to pinpoint a precise U value in order to label all external wall structures. Each and every wall is different, and will possess varying thermal capabilities. However, you can see some typical U values for a cavity wall, a solid wall and an insulated wall below:

• Cavity wall (no insulation) 1.5 W/m²K
• Solid brick wall (no insulation) 2 W/m²K
• Insulated wall 0.18 W/m²K

When both are without any added insulation material applied, cavity walls are much better insulators in comparison to solid walls.

This is due to each wall’s construction, with the former containing an insulating gap between two layers of brickwork.

Yet whichever wall type you have, an insulated wall will always offer a better U value, than one left unprotected.

External Wall Insulation U Values

When it comes to choosing an external insulation product for your property, most homeowners mistakenly believe that external wall insulation U values should play a predominant part in their decision-making.

However, such single-minded focus is inadvisable. But why?

Primarily because a U value, on its own, is a relatively useless measurement. Why do we say so? For a number of reasons really!

First and foremost, a U value measures only heat transmission, as in how much heat can pass through a material. It does not measure that material’s resistance to conductive heat flow – like an R value does. A U value is only really helpful if considered along with all of the other associated measurements.

Furthermore, external wall insulation u values do not take into consideration the effect of the following factors on performance: moisture, steam, high winds and inclement weather.

Which is pretty funny really considering external walls sit outside – in the UK, where we have some of the most miserable weather going!

U value tests are conducted in laboratories where they are not subjected to the onslaught of the elements. So in the real world, these U values mean very little.