Post by Taz Loomans:

Did you know that you can legally build a structure using light straw clay in Portland, a natural, non-toxic insulation material that has been used for centuries throughout the world? We are proud to say that we helped the first such structure be permitted in the city of Portland and it is now under construction.

[Aside: Light Straw Clay is a combination of straw and clay. The first known instance of this natural building material is from the 12th century in Germany.]

An environmentally-concerned client came to us last year and requested that we transform her garage into a bedroom with a greenhouse, except that it must be built with Light Straw Clay. Luckily, we knew from previous experience and from a process we helped pioneer, that there is a legal path to building with Light Straw Clay thanks to this recommendation of the Alternative Technology Advisory Committee.

Because we were converting an existing garage into this wonderfully insulated Light Straw Clay living space, we retained the existing studs and sheathing. Light Straw Clay is never used structurally, but rather as a "filling" in structural Larsen Trusses. Below is what the Larsen Truss looks like. It is two 2x4s connected with a cross member creating a hollow frame that can be filled in with Light Straw Clay. Light Straw Clay walls are a full foot thick!

It is important to keep the Light Straw Clay within a wall completely dry so that the clay doesn't get wet and therefore lose it's form and attract mold and pests. So it's important to add venting in the walls on both the top and the bottom and make sure there is air flow throughout the wall. These vent holes had to be coordinated with our structural engineer to make sure that we had enough shear reinforcement to meet seismic code requirements. You can see the vent holes below on this project:

This mesh helps keep the Light Straw Clay away from the plywood sheathing, creating an air-gap that is necessary for air-flow:

Because you want to keep Light Straw Clay walls dry and we live in a wet climate, it's important to have a deep overhang to keep the rain from directly hitting the wall:

The benefits of Light Straw Clay is that it is a natural, non-toxic and locally-source insulation material. And it is a material that can be installed with community help, because it is done by tamping down the clay and straw mixture in courses and with a little guidance is easy to learn. The one-foot-thick walls also make for very nice and deep window openings.

Our friend and natural building expert Wolfgang Kahler will be installing the Light Straw Clay. And the walls are slated to be finished with a plaster finish which will be done by our friend and plaster expert June Bonnheim. On the exterior, they will have 4" lap wood siding. 

If you're interested in building in Light Straw Clay, contact us and we'll help you design and permit your structure!

As the City of Portland prepares to relocate the Right 2 Dream Too homeless community to inner Southeast Portland, the site plan is up for approval this week. This design is a product of a collaboration between Merrill Architecture, The City Repair Project and Communitecture, working hand-in-hand with members of R2DToo and City Council. Stay tuned here for further updates!