Cob: RE: Sealing cement roofs

[Darel Henman]

Mike,
  water getting into cracks and then freezing will expand and cause
cracking on any material.  This happens even in rocks and boulders, not
to mention cement wall.   A lesser form of damage to cement walls is
spalling, where moisture gets trapped between a waterproof barrier and
the cement and little by little crumbles small particles of the cement,
as if a cement termite was at it.  This is regardless of the temperature
inside or the other side of the object if the exterior region is below
freezing and has water in it.

Darel

Mike Swink wrote:
> ...............
> In germany there was a problem with one solid wall that would allow the temp
> outside when very cold and inside very warm would set up moisture and freeze
> causeing the wall to crack.
>