Moisture Data

Pacific NW Strawbale Structures


We have built and are testing three different structures in the Pacific Nw, more particularly the Portland area for moisture and the viability of strawbale construction as an option for building materials in the temperate rainforest

All of the structures have the same type of moisture sensor. These were constructed by hand from the specifications of Habib Gonzalez. See The Last Straw #22 for specs.  

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# 1  Tamarack Strawbale Studio Project

This project was constructed as a student workshop beginning in 1997. It is a 10' x 12' loadbearing structure with 3 coats of exterior stucco (earth/ lime and sand/ and a thin cement final coat). On the interior is 2 coats of earth and sand plaster all applied in 1998. In 2002, we applied 2 more coats of pouzzalan (fly ash) based stuccoes to finish it out.  We have been testing this structure since June 1999. There are 12 moisture sensors placed at various heights and depths.  There are four sensors that are the entire width of the bales that are closest to the exterior stuccoes.  The other 8 are placed at center of bale either low, mid or high in the walls.  The readings are taken maually with a timbercheck meter at random.  Indoor and outdoor temperatures are also monitored.

The following charts give in detail how the building is functioning thus far:


all files are in pdf format

loadbearing strawbale library ALL 12 sensors

library stuccoes only

library south wall

library north wall

library east wall

library west wall


#2  Solar7.83 design studio infill project

The studio project began in spring 1999. An existing garage, non-usable modified and transformed into solar7.83 design studio, now further being modified as a studio apartment. The north and west walls are strawbale infill. The existing structural walls were left intact, leaving aluminum siding on the exterior of 2 x 4 studs with paneling on the interior which the straw walls were butted upon. Finishing the externally pinned straw walls are burlap and 3 coats of clay slip. A reed matting was placed on 3/4 of the wall for aesthetics.

There are 6 moisture sensors within the walls, 2 on the west and 4 on the north wall. These as well are placed a various heights and depths.

sb sensors

sb sensors with added hydronic space heating


# 3  The Gonzo (an earthsheltered strawbale shelter)

Constructed as a student workshop in the summer of 1999, the Gonzo is still under construction. The interior is almost complete. There is one moisture sensor in at present, but a plan for 12 in the very near future will be installed. The one sensor that has been in for a month reads a steady 7 percent near outer bale at earth berm right above the tire foundation, exactly where we would expect to find the most moisture. Stay tune for more updates on the Gonzo.