Although we don’t cover straw bale landscape walls in the book, some of us have experience building these.
If you treat the straw bale garden wall like a small house—elevated footing, small roof, water insoluble plaster—they can last quite a long time. If you stack the bales directly on the ground and apply plaster over them the result will be that quintessential “adobe” wall look we love.
But rain from above or ground moisture from below will get into the bales. Most water insoluble plasters like lime or cement-lime are porous, not water proof, and clay plasters tend to erode…and as moisture gets in the bales will gradually compost. I have seen several straw bale landscape walls that looked great from the outside, but were actually hollow inside. The bale “scaffolding” had slowly disappeared, leaving a mesh reinforced cement-lime skin. Still looked good, but as holes got knocked in the plaster the walls became habitat for all manner of critters.
You might ask others in your area who have built a straw bale landscape wall for suggestions about durability.
Would a foundation of papercrete or the like make a difference?
There's very heavy monsoons out here and I've looked at the straw clay bricks, papercrete bricks as an outer layer over the bales.
My only concern is perhaps the foundation cracking?
Definitely going for an adobe look!
Hi Kristen, I don't think papercrete is rated for below-grade use. Anything you put on the ground that has plant based fibers in it materials in it (straw, hemp, paper) becomes food for microbes if the moisture and temperature conditions are there. I'll note that that traditional adobe look we love was made from adobe bricks, probably set on a foundation of some sort (stone, rubble), and then plastered with either earth or lime. Both of these required periodic maintenance.
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World Domination Gardening 3-DVD set. Gardening with an excavator. richsoil.com/wdg