Now one more thing. I would like to build in some
seats in a sort of alcove in the wall. I am thinking of ways to do it
without backer boards.
If the soil is predominately clay, one way to form is to carve out a seat
in the dirt, lay four or five layers of mesh and slop on the mortar. You
can make the seats form fitting by putting on a final thick coat of mortar,
letting it set up a bit, cover with plastic sheeting, then sit on it and
wiggle your butt a bit.
Seats can be made freeform or working with an existing seat and back.
Plastic chairs are ubiquitous and old, busted wooden chairs are widely
available. Remove the front legs so you can slope the front backwards at
the bottom, so people can tuck their legs if they choose. Cover the form
with the wire mesh and apply mortar.
Be sure to make a drain hole in the low part of the seat or else rain and
dirt will collect there and be a challenge to clean. Just stick in a piece
of 2-inch PVC or a tin can and remove it after the mortar has dried. For
super drainage, stick an old busted bucket with holes in the bottom under
the seat before it is formed. To glean maximum fun, wait until your guests
have been seated for awhile before you tell them about the time a snake got
in there.