Laying the Adobes
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Q and A: I am building an adobe home about 8 miles south of Jemez Springs NM (just north of the Jemez Pueblo). This is my first experience with adobe construction, and this being the case, I have some areas of uncertainty. The most pressing of those right now is that, this being December, my adobe mortar (an earth mortar) is freezing at night. I've asked some folks around here, and have gotten the "don't set any adobes after 2p.m." rule.

I usually say don't lay adobe after mid-November. If you are not using cement based mortar, then frozen mortar will thaw out with no dire consequences. Cement mortar is ruined by freezing.

I followed that yesterday, but arrived this morning to see that even so, the mortar froze over night. Even the courses I was laying at nine or ten in the morning seem to have frozen. The temperatures have been in the low to mid 40s during the day and down to the 20s at night and the house site gets full sun from 7:30a.m. till around 4p.m. I have heard the warnings about the damage that freeze thaw can have on the mortar joints, however, given that even the first courses of the day froze, and the fact that I'm getting as much sun as possible, it doesn't seem as though I can avoid some freezing. Is there some level of acceptable freezing? Is there any truth to the Two p.m. rule?

The two pm rule often gives the mortar time to dry enough so that there is little moisture to freeze at night. It's a good rule, but I like the November rule better. My best advice is to take a break until mid-February or better yet, mid-March. If you cannot do that you can switch to a cement based mortar and add Anti-Hydro which is an antifreeze well known and used by concrete block masons.

I am using all unstabilized bricks. To get around the NM adobe code requirement of having the first course be semi stabilized, I made the foundation stem wall 4 inches higher, so there will be 4 inches of concrete in between the finished floor and the first course of adobes.

That is not really going around the Code.That is meeting the other option that the Code gives.

Q: The house I'm building is hexagonal in shape, with some rectangular rooms branching off. So instead of 90 degree corners, I have 66 degree corners. My brick dimensions are 10 BY 14. Last fall when I began to lay the first courses I was having difficulty figuring out a way in which to overlap the 66 degree corners. On one course, it's easy to diagonally cut two adobes to the appropriate angles so that there is a break right at the 66 degree corner, however, on the next course there no way possible to straddle the break below with a full brick. The only way to straddle the break from the first course is to do so with a brick which is trimmed down to be somewhat on the small side.
My question: Would you advise 1. laying up the courses so that at the 66 degree hexagonal corners, there are breaks in every course, or put another way, not straddling breaks with whole brick at the corners, but having breaks(at the corners) every course, and then tying the walls together with durowall...or 2. Overlapping the breaks at the corners with a solid brick above, even though that brick not be a full 10 by 14. or 3. Neither of these, but something I've not yet thought of.

A: The Code requires a four-inch overlap from one course to the next. Therefore even on standard walls and corners it is not necessary to have the bricks of one course centered over the joints below. I would say that your option 2 is the way to proceed. It is always good to have some bridge over joints in the course below. Or maybe instead of having any joints right at the corner, one course could run beyond the centerline to the right, the next course could run beyond the centerline to the left. Then for good measure reinforce the corners with Durowall about every fifth course. Your house will be perfect.