Stucco News
Question and answers on Stucco and Plastering-- December, 2015
Optimize the join between new stucco and old?
Thanks for excellent information nicely presented. Just spent an hour browsing your site.
I’m more of a cabinet guy, but I rebuilt the 10’ x 10’ laundry wing on my small single-story SoCal home. It’s a wannabe craftsman kit home with redwood clapboard built in 1917, and received stucco in ’47. Good materials, decently applied, 5/8” average thickness overall. No signs of cracks or degradation from moisture.
I cut the old stucco with an ablative blade on a circular saw. One cut, nice & clean. Now I’m ready to apply paper and pre-furred woven wire lath. How do I optimize the join between new stucco and old?
There’s a vertical cut nice & smooth, showing base coast with embedded wire, and top coat. The cut slices the tarpaper beneath, and just scores the outer skirt of the clapboard. Then my new sheathing. Maybe I could work heavy wire into the horizontal gaps between each clapboard, even epoxy them in, and tie them to the new lath? Maybe I should chamfer the edge of nice clean cut so new stucco has a chance to fair in? Basic integrity of the whole stucco web is my chief concern; appearance matters much less on this utility porch at the rear of the home. |
Here, a mixture of flex-con, an acrylic bonding admixture, and portland cement with no sand is painted on the join. The surface is left as rough as possible. This not only prevents edge cracking, it avoids a nasty hump. |
A rough edge would bond better but this is what we have been doing lately for our joins.
I believe heavily in flex-con, but there are other acrylic bonding admixtures.
We mix pure flex-con (no water)
portland cement (no sand)
in a cup or something until it is a paste.
Paint this on your join leaving the paste rough.
You may want to wet the join first.
This will work 95%+ of the time
Thanks so much for visiting my site