All Need To Know About U Values When Building An Extension

A Guide to U Values in an Extension

A Brief Tour of U Values!

What on earth are you doing reading this? Are you some sort of a scientist?

We most certainly are not, so don’t expect any technical info whatsoever.

This article is written on a strictly “need to know” basis. If you really want science, go and “wickiepedia” for it.

A “U value” is a differential of measurement of temperature loss between 2 materials rated in Watts per Square metre.

If you want to keep heat in, (or if you live in Africa, out), the lower the “U Value”, the better.

If you understand this, maybe you could explain it to us!

Insulating to Improve U Values

Now then….how do we keep heat in a building? We insulate it of course and your extension will have loads of insulation incorporated into the walls, floors, roof, windows and doors and by law, each one of these components has to be manufactured or built to comply with a required “U value”

Your architect will know what each requirement is. Each material or process he specifies, will meet the current legal requirement, your builder will build to the specification and the building inspector will check that everything is done properly.

And you will pay for it all!

None of this should bother you visually, except for one thing. If you want loads of glazing, you might be unlucky.

Normal double glazing doesn’t have a particularly low U value compared to a well-insulated wall.

“Excessive” glazing therefore, can affect the overall efficiency of the extension, too much heat will escape, the gulf stream will stop dead in it’s tracks and it will be all your fault.

It is possible to use “special glazing” though (ask your architect), or how would all that transparent foolishness on Grand Designs get past the planners?

Oh yes… a nice compensating turf roof with a couple of goats on it. (I said I wanted glass not grass!!!)

I wonder what the “U value” of a gooseberry bush is?