We finished the T-brick shed about five years ago. To recap that construction project here are the primary parts:
1) Rubble trench foundation with a french drain
2) Lime stabilized soil (sand, clay & lime) grade beam
3) 1 foot wide lime stabilized soil (sand, clay & lime) stem wall (bottom two feet of the wall)
4) 6 more feet of 1 foot wide cob (sand, clay and straw) wall
5) A mono slope roof framed with dimensional lumber and clad with metal roof panels
You can also watch time lapse video here
This was my first solo construction/natural building project I made several mistakes including:
1) Inadequate drainage/water diversion on the uphill (west) side of the building.
2) No waterproof membrane between the stem wall the wall. This allowed moisture to wick up the wall.
3) Not including straw in the stem wall.
The poor grading trapped moisture on the uphill side of the shed for prolonged periods of time. Water would wick 2-3 feet up the wall and with no straw to hold it together sections of the wall calve off. The corners on the uphill side were most affected.
Fortunately, cob is pretty forgiving and the shed didn’t fall over while I was working on our cabin. To fix the problems I set out to do the following;
1) Fix the grade by sloping the ground away from the shed and installing a french drain to move water from the uphill side of the shed to the downhill side.
2) Patching the damaged walls with lime stabilized cob.
3) Plastering the damaged areas with lime stabilized plaster.