[Strawbale]lime and earth plaster

Rene Dalmeijer rene.dalmeijer at hetnet...
Mon Oct 4 03:10:22 CEST 2004


At 07:36 AM 10/2/04, you wrote:
>We are renovating an old house and have plastered our walls with earth
>plaster. Most of the walls contain tubes witch are connected to our
>central heating system. The walls itself are made of f brick as is the
>foundation. We have a lot of moist climbing up from the walls and some
>areas won't dry.

This is a serious problem not only for the building but also regarding the 
health of the occupants you should do something about it.

1) Ideally drain the foundation with a drain pipe at the base of the 
brickwork foundation. At least try to find out why the surrounding ground 
is so wet. If it is due to a high water table then it will be very 
difficult to deal with by drainage only.
2) Basically what is most probably missing in the building is a decent 
"Dutch term- Trasraam" this consists of a few courses of brick work around 
ground level which have been baked at a high temperature making them much 
less hygroscopic. Another additional measure is using special mortar that 
is also less hygroscopic thus creating an even more effective water 
barrier. Obviously these measures are difficult if not impossible to apply 
to an existing building. Various measures are available though for 
retrofitting such a problem, though the first option mentioned, drainage is 
by far the best. Most are based on impregnating the brickwork with some 
kind of proofing goo making it less permeable. This is mostly expert work 
and difficult to execute yourself.
3) Ventilate and aerate the brickwork. This requires perforating the brick 
work just above ground level with a regular pattern of deep holes d=15-30mm 
at roughly 300mm centers. The holes have to be plugged with perforated 
covers to prevent critters crawling in. The holes should be angled upwards 
to allow rain water to drip out otherwise you could advertently cause frost 
damage. Drilling should be done with care to avoid excessive damage to the 
brick work.

>There seems to develop some white powdery fungus on the
>lower part of some inner walls. We thought about stripping the lower part
>of the wall and use a lime plaster instead. Would this solve our problem?



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