[Strawbale] 5 perms / no ventilation; and top-of-wall (Mark Piepkorn)

[Sigi Koko]

My 2 cents on top of wall detail...

Having moisture tested numerous strawbale walls, I have always found that
the moisture is higher at the bottom of the wall, not the top of the wall.
(I can only assume this is due to the play of gravity.)  I'm not saying that
condensation at the top of a wall is not a valid concern, just that over
time any moisture there seems to work it's way down, not stay up in the
wall.  The top of the wall is also a rather susceptible place for moisture
to get into the strawbale wall system undetected -- for example, if there is
a roof leak that is not known, and the leak drains into the strawbale wall,
it would be undetected until the moisture content in the wall is so high as
to require drastic measures (replacement!).  On the other hand, if a barrier
over the top of the bale wall detours any leaks to the sides of the wall, it
will create a stain in the plaster, indicating to the building
owner/occupant that there is a moisture issue to be dealt with.  They know
to fix the roof, and at worst need to refinish plaster.  The bales go
uneffected.  I use 2 layers of roofing felt over the tops of bale walls for
this purpose.  (The second layer is to provide a safety net.)

Thanks, Sigi


 
 
Sigi Koko
be the change you wish to see...

DOWN to EARTH DESIGN, inc.
natural building design
environmental consulting 
www.buildnaturally.com
215-540-2694 (PA)
202-302-3055 (DC)