[Cob] update on trench issues

[Damon Howell]

David,
	I did a quick experiment with my urbanite before I built my  
foundation wall with it. I placed a piece in about 3 inches of water  
for a full day. The next day I measured. The urbanite I used absorbed  
only about quarter inch of water. And if you're using a rubble trench  
anywhere from 6-12 inches, the water isn't going to wick up through  
your foundation from beneath, it will get it's moisture from the dirt  
touching the sides. I used 8 inches of gravel, and three feet of  
urbanite. Now I think back on it, it may be overkill, but hey, I  
didn't want all my hard work to be destroyed by water!

Damon in GA