Straw Bale Shed Foundation & Retaining Wall

The strawbale shed is moving along in spite of the Coronavirus shutdown.

After doing the rough grading in November of last year, I focused on other tasks until early April when I returned to this project to start on the foundation. My Dad put in a lot of hours assisting me and was a huge help! We laid out the forms, leveled them, installed the rebar, and finally poured the concrete in early May.

Almost ready for pouring concrete – minus the vapur barrier that we somehow managed to sneak in the bottom after everything was complete. The red lines are a 1/2″ PEX tube on 12″ spacing for hydronic space heating.

My brother and Mom came out to help with the concrete pour and made the job go smoother. Unfortunately concrete went off quickly in the hot sun even with 1% retarder, so it doesn’t have a flawless finish. The inside portions finished up well enough though.

After curing we spent three weekends in late-May and early June laying the block retaining wall for the back. For the back of the retaining wall, we used double 66’s (8 x 12 x 16) blocks set perpendicular in the wall. This way, the wall will be wide enough for the strawbale walls that will rest on top of it.

Break during mid-progress on the wall

There are three courses of horizontal #4 bar that run the complete length of the wall. A #3 bar passes vertically down thru the outside cavity of each block to the bottom of the wall where it meets and and is spliced with a #3 bar coming up from the foundation (~20″ overlap). The finished wall will be incredibly strong!

The finished block wall waiting to be grouted. The horizontal tie bar is doubled along the back of the shed to provide hold-down strength for the double sill plate.

Setting the blocks was a steep learning curve but the results were excellent. In the end, we were setting about 6 double blocks per hour. Not only are the double blocks heavy, but they are also more difficult to set perpendicular. The single 88 blocks set much faster – probably 10 or so per hour. Still not fast but it takes a lot of skill to do well. Overall, I’m glad this portion of the build is behind me.

Fine-tuned shed design. The alcove on the East side provides shelter for “utilities” (gas, water, electricity).

I’ve been working on many little details on the inside and the framing over the last month. It’s really starting to come along, although it will be a bit more complex than I initially anticipated! Thinking thru where the “utility” lines need to run and the framing beforehand will be worth it, though.

Framing views. Shear / lateral resistance is provided by the wire mesh – plaster walls. Wood beams and posts support the vertical loading.