Obviously you cannot add more insulation on top of the batts in the wall cavities.

There are few if any, mechanisms that operate to dry out such wall cavities.

In London alone, £62.5 million was wasted as energy escaped through wall cavities and cracks.

Then push any excess cable back into the wall cavity.

The holes should enter the wall cavity directly beneath the existing box and the opening for the new one.

At the new box opening, repeat the steps for fishing the cable through the wall cavity.

Eventually the box will break free and fall back into the wall cavity.

You can assume, then, that it is approximately the size of the wall cavity, or 3 1/2 inches thick.

And in many cases, he said, insulated wall cavities fit the bill nicely.

In this way it can be easily guided through an empty wall cavity.