[Cob] Cob in Montana

[Sky Orndoff]

Hey All!

Interesting recent dialogue! Thanks, everyone.  Damon, no offense taken.  Also curious about what you mean by the 20 degree fluctuation.  To add a bit of irony, cob has had a significant place in my life over the past year.  Janet, way to forge ahead.  Good luck, and enjoy!  Chris--interesting perspectives.  Want to tell us more about what cob to conventional hybrids you've seen?

Sorry to be repetitive, everyone, but here's a description of the project we just completed:  We are pretty happy with the cobwood structure we built.  It is finally closed in and properly insulated.  My friend, Kyle, the homeowner, who lives in the approx 180 square feet house full time is quite happy with the final result.  The house is about 2/3 conventional stick framing, with a cobwood room attached.  For heat, we installed a rocket mass heater as per Ianto's book.  For that room, we sandwiched 10 inches of conventional cellulose insulation between two six inch cob walls.  These walls (and the insulation) are penetrated very frequently by 23 inch logs, making a cob variation to the classic cordwood building style.  Hopefully the mold and water issues which have been experienced don't arise in this hybrid building style.  We will see.  Cellulose has a potential to absorb a lot of water.  But Helena, Montana is sunny and dry (and cold) and
 not typically a haven for either moisture or mold issues.  

Plus sides of the cob room:

Shape makes tiny space feel big but still cozy.
Tiny space heats well on little wood.
Thermal mass of walls and Rocket Mass Heater (RMH) hold heat.
Insulation seems to help retain heat for long periods.
RMH bench very relaxing when warm.
Thick walls useful for shelf space and wood storage.
Local building materials; super inexpensive; low impact.
double-slope ceiling is neat, sends heat from RMH to other parts of house.
Pleasing aesthetics (so we think)

Down sides of the room:

Rocket MH takes a while to start warming house up.
Rocket MH occasionally smokes.
Rocket MH takes a lot of caring for to minimize smoke entering room.
Cob walls take a long time to heat up--if the house gets cold, the walls feel cold for a long time.
Cob took a lot of time to mix and apply--a lot of labor for a small space!
Haven't yet plastered, so cob "dusts" on clothes and hands.

Anyone with advice on fixing these issues, we're all ears!

If you are still interested and haven't yet, please check out www.earthartbuild.wordpress.com.  There we have pictures of the cobwood room and lots of our other building projects.

Sky