Cob: Re: Radon

[Shannon C. Dealy]

Here is my response to someone else who privately asked me a similar
question a month ago.

---------- Forwarded message ----------

> I would like to know what the radon levels are, in a cob home?

Radon in a home has nothing to do with cob itself, it is a function of the
composition of the earth/rock strata below your house, and the design of
the house. Radon is a breakdown by product of Uranium, and if there is
Uranium in the earth somewhere below the house, radon can work it's way up
to the surface and into the house.  With modern housing and the emphasis
on sealing against air penetration from outside, once the radon gets in,
it may be difficult for it to get out so it builds up to potentially
dangerous levels.  The best way to prevent problems with radon (aside from
not building in areas where radon is a significant problem) is to have a
well ventilated crawl space under your house and a well sealed floor above
it.  It also helps if the house itself has adequate ventilation.  If you
are interested in using an earthen floor in an area with radon problems, I
would want to make sure the floor is well sealed, the house adequately
ventiated year round, and run periodic radon tests the first few
years.  It might help to try and find a way to ventilate under the cob
floor such as by using a thicker coarse gravel bed and devise some means
of ventilating it, but since I haven't heard anything about earthen floors
and radon infiltration, the effectiveness of anything I could say here
would be pure speculation.

If you are concerned about radon emissions from the cob walls themselves,
it means there is Uranium in your cob mix and therefore, presumably in
the surface soil around your house which the cob was made from, in which
case you have far bigger problems than radon.


Shannon C. Dealy      |               DeaTech Research Inc.
dealy at deatech.com     |          - Custom Software Development -
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