Expert: Bruce E. Johnson - 1/21/2009

Question
QUESTION: We built a house several years ago in South Carolina.  The exterior is real stucco.  Within the first year, the stucco began to fall off the seams.  It continues to do so, however does not seem to be falling off anywhere but the seams.  Our builder insists that this is normal for stucco and that the solution is to patch and paint to match.  I accepted this at first, but within two weeks the places he patched are falling off again.   So my questions are is this normal for stucco?  And, even if it is not, is it okay to just leave it since the peeling is restricted to the seams?

ANSWER: Hi sandra, by "seams" are you talking about the expansion joints?  If so then it sounds to me like the stucco contractor didn't use the proper type of expansion joint material.  Stucco expansion joints are made up of two pieces, one of the pieces slips inside the other so that as the building expands and contracts the joints will move and not crack the stucco.  Once the expansion joints are finished these seams are then caulked with urethane caulking to keep moisture out.
I hope this information helps feel free to write again regarding this or other matters, sincerely bruce e johnson..bejohnsonconsulting.com

---------- FOLLOW-UP ----------

QUESTION: The stucco is coming off of the corner beads, which are plastic (PVC).  I was told that they had to start using PVC instead of metal beads, as the metal was rusting and leaving rust stains (this was apparently mandated by law).  I was also told that unfortunately the stucco does not stick as well to the PVC as the metal, which results in the stucco falling off after a couple of years.  Further,the only way to cover the PVC in a way that can match the stucco (after it is repaired) is by painting it.  Note that this is Portland cement stucco.

Thanks

Sandra

Answer
Hi again Sandra, the metal corner bead does have expanded metal that will probably hold the stucco a little better than the pvc corner bead but properly installed corner bead and properly installed stucco will not fall off in the manner in which you are talking about.  There are bonding agents that help the stucco stick better. Plus the pvc corner bead has holes in it so that the stucco, when applied properly, will grab hold and anchor.  I agree that cheap metal corner bead if it is galvanized poorly will rust but I have never heard of a building code that forbids the use of metal corner bead.  

I suggest when patching the stucco that a good bonding agent be used to coat the repair area and also mixed with the stucco itself.  Also this patch should cure for at least two weeks, preferably 3-4 weeks before being painted. I hope this information helps feel free to write again regarding this or other matters, sincerely bruce e johnson..bejohnsonconsulting.com