Building the Light Clay Straw Porch

by ziggy on June 26, 2013 -- 5 comments -- Follow

Light Clay Straw (Slipstraw) Walls

Our light clay straw (slipstraw) porch walls are on the way

The north porch of our straw bale house has been occupying most of our construction time these days. As of only a couple of weeks ago, the porch was still largely open, with only framing and a few windows installed.

We decided to go the wall & windows route, instead of just screening the space in, because of how exposed this part of the home is to the north and west weather. Also, the space is much more versatile this way, too. We decided to do light clay straw (a.k.a., slipstraw) infill walls.

It’s been an enjoyable process thus far.

Clay Straw Walls

Clay straw walls going up

Building Light Clay Straw Walls

We started off the closing-in process by building stud walls for the three open sides of the porch. On the east and west, it was particularly easy, because we were able to just slide the stud frame right into the opening made by the timber frame. On the north, we had to work around the posts and braces a bit more, notching into the stud frame for it to fit properly.

We’re not going for insulation in this case, as the porch is just that — a porch, and a standard 2×4 stud frame sufficed here. Overall, I think closing in the space proved to be rather economical, as we did not use very much lumber, nor did we need very many straw bales to produce the light clay straw.

With the stud frame in place and firmly screwed in, we installed our windows. We went for as much window area as possible, for ventilation, the view, and light. I’m pretty happy with what we came up with. The wall terminates at a perfect 3 foot height on the east and west, and although it is somewhat awkwardly lower on the north (maybe 2’8″), I think it still works. (We did a shorter wall on the north so that the tops of the windows would align with the door.)

Light Clay Straw House

Light clay straw, up close and personal

Working with Light Clay Straw

Working with light clay straw is decidedly simple. Mixing it is a breeze, as it stuffing it. The only challenge was stuffing parts of the walls where braces created interesting spaces that required a special form.

As you may or may not know, light clay straw is just that — loose straw very lightly coated in a thin clay slip. Think of the clay as a melted milkshake consistency. Light clay straw is tossed like a salad with the clay in either a wheelbarrow, or on a tarp. Forms (either plywood, roofing metal, or 1x) are attached to either face of the stud wall, and the material is stuffed in place. Forms can be moved up the wall immediately; there is no need to wait for anything to dry before you continue upward with the wall. For something like a 2×4 wall, it is especially quick. (For more about light clay straw house construction, check out this article by Jacob.)

It’s amazing how well the material stays in place, without the need for drying time to continue work, even in wall sections that are pushing 30″ wide!

What’s Next for the Porch

Ideally, we would have had the siding up on the exterior before doing any kind of plaster work. However, we deemed the walls stable enough to apply clay slip to the surface without risk of pushing the walls out. Needless to say, now that the straw work is done, we have our sights set on installing our live edge siding on the exterior, but not before trimming the windows first, of course.

Straw Bale House Porch

Inside the (unfinished) porch, looking west

Once all that business is done, we can move back inside and do our interior trim, and plaster work. All these steps should result in a beautiful place to sit on our swinging bench, not to mention cook — one of the main functions of the porch is a space to cook meals in the warmer months. Our kitchen will go along the east side of the space, and if all goes well, our round table that currently sits inside can be moved out there, too.

Straw Bale House Porch Interior

Looking north in the porch

Even in its current unfinished space, the porch is already adding a whole new dimension to the house. I like it.

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  • Out Standing Z man!!!! 🙂

    Is this where the live edge siding will go?

  • Consider plastering one coat of clay plaster on the exterior before siding. This will reduce potential insect habitat, act as an air barrier as well as improve the thermal performance of the wall. I speak as a straw clay builder in Michigan trained by Robert Laporte.

  • Thomas: interesting tip. Didn’t think of it that way before. In fact, the plan from the beginning was that we’d put the siding up first, and use that as an automatic form (and thus we would have never had the chance to slip the exterior). Of course, the siding took a lot longer than expected, so we installed the straw anyway…

    Have you ever done straw clay in conjunction with timber framing? I’ve been thinking a lot lately about the most effective/efficient way to create a straw clay wall between structural elements in a timber frame, while still being able to wrap the frame.

  • Steve

    http://www.youtube.com/watch?v=8JsVai3sJUg

    Here’s strawbale around timberframe

  • Yes, some of the straw clay projects I have worked on have timber frames. Most of Robert Laportes timber frames get “outsulated” with clay straw. You can see this on the Econest website.

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