The Journey of Constructing a Straw Bale Greenhouse

Straw bale construction makes a novice builder’s greenhouse affordable, eco-friendly and easy.


| May/June 2001



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In a cold climate, the north wall of any greenhouse must be extremely well insulated, which makes straw bale construction an excellent choice. Straw bale walls have a minimum R-value of 38, twice that of an insulated stick-built wall, which averages R-19. Even in winter, Suzy is able to grow spinach, chard, herbs, and Romaine and butter lettuces in the higher beds set against the straw bale walls.

Photography by Laurie Dickson

Suzy McCleary is a farmer, not a carpenter. But when her second greenhouse collapsed underneath the heavy snows of Colorado’s southwestern mountains five years ago, Suzy took matters into her own hands. Her first greenhouse had been made of rebar and plastic sheets. The second had been PVC pipe and thicker plastic. She wasn’t going down that road again.

“I read about straw bale construction and loved the whole idea,” she says. “It seemed like a way I could build, plus it’s environmentally friendly.' With a borrowed book, and a little help from her friends, Suzy built her own straw bale greenhouse. That was five years ago. “This time I used the tough stuff,” she says. “This greenhouse will be there for good.”

Before she started construction, Suzy did her homework. Then she asked a carpenter friend to help build a post-and-beam frame. Together they designed her straightforward structure: a lean-to with two side doors; a tall, solid north wall; a steeply pitched windowed roof; and a short south wall made of windows. The greenhouse’s size—sixteen-by-thirty (480 square feet), with a four-foot high front wall and a nine-foot high back wall—was dictated by the site, which includes an irrigation ditch to the east and trees to the west.

For the frame, Suzy bought locally milled rough-sawn pine and fir. She and her friend poured concrete for each corner support and for the middle supports, spaced eight feet apart. They placed vertical pieces of rebar to protrude one foot above the ground to stabilize the straw bale walls.

For a foundation, Suzy used sandbags. “It was cheaper than concrete,” she says. She acknowledges that in wetter climates, this may not be a good idea because the water may seep through the sand, get into the straw, and cause it to rot.

Suzy bought the straw bales—fifty-pound two-string bales for two bucks apiece—just across the border in New Mexico. Peg helped her stack them between the posts and onto the rebar on the long north wall and the two side walls. They pounded more rebar through every fourth bale for reinforcement.





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