On Tue, 22 Mar 2005 20:17:31 +0000, Conrad
wrote:


Hi!
My current project is to have an enclosed front porch - that is an
add-on to the front of the house approximately 2 metres by 1 metre. It
will have double glazed windows and insulated roof. I had intended to
have cavity wall with a 2 inch/ 5 cm gap for insulation.

A surveyor acquaintance says that the firm he works for fits double
brick without a gap so as to allow an extra 2 inches internally per
wall.

This all sounds very well, but won't that defeat the object of having
energy efficient / double glazing? Or should I be cutting my costs and
having single glazing too? Any comments would be welcome.

Thanks

I don't think that the gap in a double-wythe wall is there for
heat conservation. As near as I can figure out, it does two things:
It keeps water from soaking all the way through the wall when
it rains continuously for April, and it makes a thicker and therefore
more stable wall.