A house I'm currently buying has an old kitchen extension at the back
>which is built with walls only one brick thick. I plan to insulate the
>walls by just using insulation backed plasterboard, and then fit a new >kitchen.
You would probably be better off using a polyisocyanurate foam such as Kingspan or Celotex fitted in studs and then plasterboard using standard plasterboard. This should have a better insulating effect for a given thickness and will make quite a difference to the heat loss.
>The things is, I noticed that there's a small metal grate in the wall a
>few feet from the ground which goes straight through to outside. At the
>moment this exits from the worlds smallest WC at the end of the kitchen,
>which is also windowless. The WC will be going, but I'll need to do
>something with the grate when I insulate the wall. But what? Do I just
>knock it out and fit a solid brick, or is it there for ventilation of
>the extension, and I need to replace it with something else?
The vent could have been put in because what is now the WC was once a pantry, or perhaps to provide air for an open flued gas water heater or some such. If there is still an open flued boiler, then you need to maintain an air supply of a certain size according to the boiler capacity - details are in the Building Regulations. If it were providing ventilation under a wooden floor then it also ought to stay. Otherwise, I don't see that it would be necessary to retain it as is. Perhaps replacing with an extractor fan would be an appropriate solution.
>Thanks,
>-Duncan
.andy
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