[Cob] thermal bridging around windows (Robert Alcock)

[Robert Alcock]

Hi again

I've received two replies off-list, both of them saying essentially the 
same thing: "Condensation will always form around windows, and you need 
a healthy breeze to blow away the wet air" or "the air is not been 
changed often enough".

Thanks for those replies, but I don't agree entirely. For one thing, the 
condensation in our house forms around some windows but not others -- 
not exclusively in the areas where there is extra humidity, like kitchen 
and bathrooms. There are always going to be humidity in indoor air. 
People breathe out water vapour. But cob walls are breathable, and so in 
general, the humidity inside a cob house should self-regulate in a way 
that doesn't happen in non-breathable walls, hence there shouldn't be a 
generalised problem with high humidity (and indeed there isn't, at least 
not in our house!), and no need for forced ventilation; though 
certainly, ventilation will help to solve this problem locally, like in 
bathrooms.

As I see it, the problem is that the wall around the window is colder 
than the rest of the wall surface, hence the water condenses there. 
That's why I asked specifically about how to reduce this thermal bridging.

I should add that this isn't a major problem, we're talking about fairly 
small areas and sponging down with bleach gets rid of the mould. But it 
is something I would like to prevent because it's a sign that we're 
losing heat in those areas.

Any ideas?

thanks again

Robert
www.abrazohouse.org

 though obviously you want to keep this within limits

>
> Today's Topics:
>
>    1. thermal bridging around windows (Robert Alcock)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Tue, 11 Feb 2014 13:18:08 +0100
> From: Robert Alcock <ralcock at euskalnet.net>
> To: coblist at deatech.com
> Subject: [Cob] thermal bridging around windows
> Message-ID: <52FA1500.4060302 at euskalnet.net>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>
> 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
>
>
>
>
> ------------------------------
>
> Subject: Digest Footer
>
> _______________________________________________
> Coblist mailing list
> Coblist at deatech.com
> http://www.deatech.com/mailman/listinfo/coblist
>
>
> ------------------------------
>
> End of Coblist Digest, Vol 12, Issue 14
> ***************************************
>
>