Building Underground
I recently received an email in which a man asked about using strawbale building techniques underground, as in an earth-bermed house. He wants to use strawbales due to their high insulation value, but is concerned about the effects of moisture on the bales.
I, too, would be concerned about the moisture. We are trying to figure out a way to make it work, as it would be a great marriage for sure!
I suggested that it may be possible if he could find a way to use a material that would provide a break between the bales and the backfill.
In other words, he would need to place the backfill against a structural element (what is yet to be determined, but perhaps concrete and a plastic waterproof membrane?) that would provide strength and protection from ground moisture.
He could then stack bales (the back side pre-dipped in plaster for fire protection) slightly away from that wall so as to leave a ventilation channel between the bales and the backfill assembly. That channel may need mechanical help to provide adequate air movement to protect the strawbales from moisture.
Seems a bit over the top to me, but I would like to see what other options you may have for such a job. I would really like to see this as a possibility in the future. Thanks for any input you are willing to share on ideas of using strawbale building techniques in a situations such as this.
-Andrew Morrison