Conservatory dwarf wall.

4 Dec 2004
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United Kingdom
Hi guys & gals

My conservatory, (turf cut today), has been designed with a 450mm high dwarf wall with brick facing and Celcon blockwork and a 50mm cavity. As this will become a proper living area, I am keen to have the wall as well insulated as possible. The builder was proposing to use soft fibreglass insulation in the cavity, which I think would be no use as soon as it got damp. Celotex CW3000 (25mm) looks a good bet, but is it easy enough to fit it in a 50mm cavity? Or is there a better alternative? I would also like insulated plasterboard on the interior walls, do Celotex do something like that?

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there is no point fretting about heat loss through the walls when building a conservatory, as the heat loss through the glazing and roof negates ALL efforts via floor and wall. you may as well insulate though, as to avoid surface cold spots.

dritherm fibreglass cavity insulation does not wick water and is as good a cavity insulation as any other.

most 'habitable' constructed buildings now use 100mm cavities anyhow. the most efficient being a 75mm rigid board with 25mm airgap. full fill 100mm dritherm is the next best thing.
Thanks a lot, point taken on the glass heat loss, however this one is quite good at 1.1 u-value glass, total heat loss for the conservatory (23 square meters) is only 1900 watts as designed, so I am still keen to improve any bit I can. Would you say that completely filling the 50mm cavity with dritherm is the best option? as opposed to fibreglass.
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sorry to mislead but dritherm IS fibreglass that is specific for cavity filling.

a rigid board (celotex, kingspan) will offer greater thermal protection. make sure it is fitted tight to the inside wall. i.e 75mm celotex with 25mm airgap.
This sends me back to my original question, as the gap is to be only 50mm, is 25mm celotex board an option? I am concerned that it will not be possible to fit in only a 50mm gap, that is, is there room for the builder to fit it? I am getting the impression that full fill with 'Dritherm' is the best bet.
You can fit 25mm board in a 50mm cavity, but its a right pain to use.

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