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There was an article in either "The Journal of
Light Construction" or "Fine Home Building" a number of years ago about a home
owner who was suing their contractor because their infilled timber
framed home's posts had major rot in them in just a few months after
completion. The owner wanted the infill design. The problem was the wood posts
(columns) shrank. Gaps opened up between the posts and the infill wall
system, the warm moist interior air condensed giving mother nature a prime
environment to do her work, (ROT) which is to turn wood into compost to grow
more trees. It didn't help much that the home owner was venting his clothes
dryer into the home to save energy and heat the home. The home owner lost the
case.
Solution:
1. Infill only with materials that move at the
same rate and that one can absolutely prevent gaps from opening, thereby
preventing any warm moist air from reaching the dew point inside the wall
or gap.
2. Outfill so that all wood members are inside the
wall system. Seal wall behind or between post and wall to prevent moisture
buildup and potential on the backside of the wood where you cannot see it.
3. Ventilate correctly to control moisture and air
quality.
Rastra has been used to outfill timber frame
buildings. Rastra has also been used to make the structural walls that support
timber frames. Some projects will do "Trimber" frame posts (hollow fake posts
which save wood) on top of Rastra walls, then use a real timber framing roof
system on top.
If you fill the Rastra units with something other
then concrete, be sure to have an engineer look at the effects of wind on the
wall. Wind can exert some mighty pressure on any wall. There are was to
make Rastra work as a limited load wall. Big Bad Wolf, huff and
puff.
Where are you located?
At Your Service
Tom St. Louis Pres.
T.R.
Strong Building Systems Co.
Problem Solving for Sustainable Building
TM
Distribution & Support for Recycled Content,
Energy and Resource
Conserving Building Materials
Member: NW EcoBuilding Guild
6901 Bayview
Dr. NE.
Olympia, WA. 98506
360-705-2868 FX 943-6418
http://www.baubuilder.com
E-mail tom_st_louis@msn.com
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