Info on Stucco and Plastering-June, 2019-fifty-seventh issue
Re stucco cracked stucco on block
Love your web page.
I live in the southwest (Albuquerque NM) in a 60 +/- year old masonry house that had the
stucco applied directly on the block. Over the years, it has been painted and poorly
patched in places. There are a lot of cracks showing through where the block joints are.
After buying the house a year ago, I removed a lot of ivy from the outside walls. Though the
stucco has been poorly maintained, it has held up well. Because of the amount of small
cracks at the block joints (most of these are not due to wall settling), I am considering
nailing wire mesh and re-stuccoing, unless you have an easier solution such as patching
the bad places and re-painting (I'm always open to suggestions).
If I do re-stucco, is it possible to glue/nail/attach in some way styrofoam insulation sheets
to the wall, nail mesh over it and stucco over that. I realize that this is similiar to many
synthetic stucco methods (I don't want to go there). The reason that I wish to do this is
that there is no insulation in the walls, and the inside walls have a beautiful plaster coat
that has held up over the years, and it would be a sin to insulate the inside walls (not to
mention losing interior living space to furred out walls).
Z furring can be problematic becuse now the foam and the new stucco protrude past the roof, windows, etc. making it necessary
to reflash the roof, extend the window jambs, etc. I have heard the metal creates a thermal bridge, but that sounds like a bunch of know it all double talk to me. Having additional stucco on your house will create more thermal mass, retaining cooler temperatures in a hot climate.
My chipping and bonding method here works great on block or brick that have been painted or not, and works well on old stucco, painted or not,
because you can get by with two thin coats. Nailing up metal lath usually causes a lot of cracks in the new stucco, probably due to the fact that
the mortar doesn't bond to the old wall, creating a slip joint when the building moves, expands and contracts, etc. One the other hand we get very few or no cracks using our chipping and bonding method, due to the fact the flex adds flexural strength to the mortar.
The stucco may crack for whatever reason, but the practice of nailing up lath may create lots and lots of cracks in the new stucco.