Learned lessons: Before you paint that stucco

LESSONS LEARNED: BEFORE YOU PAINT THAT STUCCO…

An older walk-up apartment in southern Alberta with batt-filled stucco-clad walls – there are thousands just like it across the province. The stucco was looking shabby, so maintenance had it painted using a recommended “permeable” acrylic paint. Just a few years later, it started to look bad again, with little rusty streaks this time.

Turns out those typical stucco walls work because they allow moisture to dry to the exterior, and even permeable paint reduces a stucco wall’s ability to dry. It is also true that: • windows leak a little rain water and a little condensation into the wall framing; • polyethylene film is a great vapour barrier but not a good barrier to moist interior air; • flashings are never perfect; • building paper is a ‘paper’ with impregnated asphalt that can wash off, so do not expect miracles; and

• even galvanized steel will rust. Luckily, only a little stud framing needed replacement and there was hardly any mould on the interior gypsum. Everything else came off from the outside including the insulation; expensive but it looks way better now with the new cladding.

So before you paint that stucco, maybe consult someone from ABEC North or South? n

Do you have a "Lessons Learned" horror story you'd like to share? Send us your pitch and pictures to info@abecnorth.org and registrations@abecsouth.org.