[Cob] thermal bridging around windows

[Nils q]

Hi,

I have never lived in a cob or earth house myself, but I grew up at germany's atlantic sea coast, one of the harshest climates imaginable. There are a lot of extremely old houses made out of natural materials, and the windows never have condensation problems because the glass planes are very thin and single pane, and in the museum village Haitabu, the anxient houses often do not have window panes at all. Glass used to be non-existent or very expensive. 

Condensation will always form around windows, and you need a healthy breeze to blow away the wet air. Since the temperature is ideally not the same on both sides (else you wouldn't need a house), air will cool down and water will form. Invite in enough fresh air to blow it away, and it shouldn't be able to grow into mold or turn your beautiful cob house into a puddle of mud. 

Since you live in a very mild, warm climate, high and/or large windows with thin, single panes will let in a lot of warmth and sun. low windows will let in cold, which flows exactly like water. Like a ship, it will come from beneath, from the corners and under the doors. In your present situation, this is actually a benefit - just leave the doors open so the damp air gets blown out :)

I hope this was helpful. I know of some very inspiring cob and natural building projects in Wales, where the climate is even harsher, the winds even wetter and more cruel than at germany's west coast, and which is famous for its five hundred year old cob villages. They will have a lot of tips, too. 

Lots of luck,
Nils

(sorry for sending it twice, Robert. I accidentally sent it only to you the first time, but thought the rest of the list might benefit from some harsh northern european wind experiences, too :)


> Date: Tue, 11 Feb 2014 13:18:08 +0100
> From: ralcock at euskalnet.net
> To: coblist at deatech.com
> Subject: [Cob] thermal bridging around windows
> 
> Hi all,
> 
> Has anybody come across this problem and if so, can they suggest a 
> solution? (Either in the present house, or for future construction)
> 
> I'm talking about condensation and hence mould forming on the surface of 
> the cob (not the plaster) around windows, where the wall tapers to only 
> about 10cm/4in thick, even though the windows are double glazed and 
> condensation seldom forms on the glass. It's especially, but not 
> exclusively, in the damper areas of the house, like the bathrooms.
> 
> Our winters here aren't especially cold -- it only gets down to freezing 
> point occasionally, with average winter temperatures around 8 centigrade.
> 
> Thanks a lot,
> 
> Robert
> 
> www.abrazohouse.org
> 
> 
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