How To Build a Straw Bale House - Community Style

by Tony Sirna

Dancing Rabbit has taken a big step forward with the wall-raising of its first straw bale cabin. Thirty friends and neighbors joined us to turn 200 strawbales into what will soon be a small two-bedroom cabin. In the following four days we progressed from having not much more than a foundation to putting trusses up and the roof on, but not before a thunderstorm had us out there fighting the wind and rain to keep our bales dry.

Laying The First Straw Bales

Our bale-tying crew: Ann, Laura, Rachel

Saturday started early with heavy dew on the ground. We'd been working for three weeks since the foundation was poured to get things ready for this day. The door and window bucks were built. Twenty-three tons of gravel were dumped in the foundation where the adobe floor will sit. The template for our trusses was done. The door bucks were ready to be bolted down to the foundation. We had all the supplies, and were ready to go. By 10 a.m. the crowds had arrived and Cecil (our resident bale laying expert) held a brief orientation to get people into the bale laying mood. We then broke people up into teams tying half bales and teams laying the first course, which was done by lunch time.

Crew Making Roof Trusses From Reused Lumber

Window bucks await placement

Meanwhile back at the common house Mark and Jim were leading a crew making roof trusses. It was a tall order to get 20 homemade trusses done in one day; especially since they were fashioned completely out of reused lumber with dumpster-dived chip board scraps for gussets (the flat plates that hold the trusses together). By the third course of bales we were starting to lay window bucks on the south side of the house. Four large windows will give the cabin some solar heating in the cold months, but will be well shaded by the overhanging roof during the summer heat. Tie-down wires were run through rebar eyebolts in the foundation and over the top plate to hold the roof down in case of winds. Each tie-down had two turnbuckles for tightening the wires as the building compresses. The bales have now compressed over two inches since the building went up (most of the compression will occur in the first four to six weeks after construction).

Once we had the first course down over the rebar pins that stick out of the foundation things went fast, sometimes almost too fast. Keeping walls and especially corners straight and plumb is key.

Finishing The Laying Of Bales And Stabalizing The Walls With Bamboo

Lindsey displays the proper stuffing technique

It was not uncommon for us to take down a number of bales and redo them until the corner was vertical. After the fifth course we could start to walk on top of the walls as the sun started making its way toward the western horizon. The walls were still a little wobbly until it was all tied together. We drove bamboo vertically through the bales to keep them from shifting laterally. Each pin was sharpened with a knife, and care had to be taken to keep it from jutting out of the wall. At each corner, rebar staples were added to make the walls interlock tightly. Seven courses in all gave us an initial wall height of 98 inches prior to bale compression.

As the last bale went into place with the sun dipping towards the horizon, the crowd gave a happy cry. It was a day of hard work, fun, and real community spirit. We couldn't have done it without all the wonderful help. Thanks to everyone!

Sunday, Day Two, started with the ceremonial removing of the tarp. The big blue monster measured 40 by 60 feet and was eerie looking in the morning sun but came in pretty handy when the rain came the next day.

Finishing Tying Down The Roof On Our Straw Bale House

A view of the walls from the inside of the building

After some bale adjusting at the corners we were ready to put on the top plate. The top plates give rigidity to the top of the wall and allow an attachment surface for a roof system. Ours were made of reused 2 x 6's and "wheat sheets", a particle board made from wheat straw and a non-toxic resin. Trusses were placed on the top plate every twenty inches to allow bales to be positioned laying flat in the ceiling for insulation. By lunch we had the top plate set in place, fastened together, and sitting as square as possible on the walls. We were a little surprised that the building's dimensions at the top of the wall were a few inches larger than at the bottom - guess things weren't as straight and plumb as we hoped, but close enough. We quickly sent the tie down wires over the top plate and secured them loosely to the turnbuckles. To keep the wire from digging into the wood the books suggested a small metal protector. We found used canning lids to do the job well and are a nifty little recycling innovation to boot.

On to the trusses. Each of the 20 trusses was made of two rafters, a ceiling joist, and a king-pin.

Aaron and Tony put the first roof truss in place

The king-pin will help support the considerable weight of the bales in the ceiling and distribute it to the walls (high school geometry in action). Each truss needed to be hoisted up by three folks and set in place. After centering the truss over the wall and checking it for plumb it was braced until the purlins went on the next day (sorry for the jargon but once you put on a roof it becomes everyday lingo. Purlins run horizontally across the roof and provide a nailing surface for the roofing).

For those curious, the building is roughly 16 ft wide and 32 feet long (outside dimensions). The roof has an 8 on 12 pitch (rises 8 inches for every 12 inches horizontal, a 34-degree slope) and the rafters, including the eaves (the part that sticks outside the house), are 12 feet long. So as Day Two drew to a close we had the walls and roof frame in place. Little did we know that the next morning would bring us two inches of rain and 50 mph winds, nearly ripping the tarp from our building. But through the fearless efforts of the whole crowd we held the tarp in place and suffered only minor dampness which dried out quickly in the next day's heat. After a day of rest and rain we got back up on our new jungle gym and started nailing purlins in place on Day Three.

The cabin awaits its steel roofing

While some folks had building experience, many were novices who developed a new respect for the 16 penny nail and a substantially improved hammering technique by the end of the day. At dusk we had the purlins in place and a quarter of the roofing steel nailed on.

On Day Four we got the roofing steel completed, and we were able to take a brief rest knowing our building would stay dry. I had once hoped we would get all this done in one day but I guess I learned something about time estimates in construction.

Making The Straw Bale Building Ready For Winter

Since then we have continued to work hard to make this space livable in time for winter. We have the wheat sheet ceiling in place with strawbales above for insulation. We have the gable ends, and fascia secured, and have screened in the soffits (all parts of the roof that you rarely think about if not building a house). We have the windows and one of the doors hung and the trim on. A middle partition is half-built (it's still awaiting electrical wiring). We have half the building covered with its first coat of plaster, using our new heavy-duty stucco sprayer; read more about plaster and see photos of mud-covered Rabbits in a future issue! Once the plastering is a little farther along and the electrical system and wood stoves are installed, Rabbits will start burrowing into our spiffy new cabin.

Learn more about:

Straw Bale House Construction
Building Our First Straw Bale House
Allium Finished: Our Firsst Load Bearing Straw Bale Building