Hold a straw bale wall together with rebar pins 60-90 cm long driven through each bale into the bale below, placed near the bale ends and at mid-span, and for the first course into the stem wall. In a load-bearing wall, add tensioned wire or polyester strapping that runs over the top plate and through the wall to anchors in the stem wall, and cap every exposed pin end.
Part of Straw Bale Construction
Pins and straps are the mechanical ties that keep bales from shifting and tie a load-bearing wall to its foundation.
Pins Stop Sliding, Straps Hold Compression
Bales are slippery against each other and against masonry. Pins, driven vertically through the bales, resist sideways movement: each course is tied to the one below, and the first course is tied into the stem wall. Straps do a different job. In a load-bearing wall, a tensioned strap over the top plate and down through the wall to anchors in the stem wall holds the wall in compression under the roof, and resists uplift from wind.
What You Need
- Rebar pins 60-90 cm long, salvaged from concrete rubble.
- A heavy hammer or sledge to drive them.
- Wire or polyester strapping, and anchors set in the stem wall.
- Caps for exposed pin ends: tape, short lengths of pipe, wood blocks or bent-over tops.
- A tensioning tool for the straps: a turnbuckle, a windlass or a ratchet.
Method: Pin Each Course, Strap The Wall
Step 1: Pin the first course. Drive pins through each bale and into the stem wall, near the ends of each bale and at mid-span.
Step 2: Pin each course after it. Drive pins through each bale and into the bale below; the parent article says to pin every course.
Step 3: Stagger the pin positions between courses so they do not line up in one vertical line.
Step 4: Cap the pin tops as the wall goes up.
Step 5: For load-bearing walls, place the strapping. Run wire or polyester strapping over the top plate and through the wall to anchors in the stem wall, and tension it.
Step 6: Check the tension again as the wall settles over the first weeks, and retighten.
Common Mistakes
- Pins that miss the bale below. They hold nothing.
- All pins in one vertical line. They create a weak plane.
- Straps cutting into the bale edge. Use a spreader on the plate.
- Straps loosened by settling. Recheck after the wall compresses.
Safety
Exposed rebar and snapping straps
An uncapped rebar pin sticking out of a wall is an impalement hazard for anyone who falls or leans on it. Cap every exposed end at once. A tensioned wire or strap that slips or breaks can whip across the work area: tension it with your body out of line with the strap, wear eye protection, and never stand under a load-bearing wall while it is being tensioned. Wear gloves for driving pins and handling wire.
What’s Next
- Learn next: Plastering and Finishing
- Combine with: Load-Bearing (Nebraska) Style