Chalky stucco at base of window?


Old 12-13-17, 07:36 PM
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Location: Florida
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Chalky stucco at base of window?

This a concrete block stucco single story building in south Florida. I was checking paint conditions on the exterior walls - using a scraper and I found the scraper digging deep into the stucco at the base of a window. The stucco is like chalk. Once I started I kept going across.

Look at this picture, I could easily take the scraper and pushed not even real hard and sank a good 3/8" into this material.

This is the stuff I broke off and fell on the ground. I could grab a handful and crumble them with my hand.

My first thought was this is badly mixed stucco? But if I scarp the front part of the wall (further from the base of the window), those are sound, hard stucco. So I continue to go at it along the entire bottom of the window. After I was done scraping all I could, and used a shop vac to clean up, this is what I end up with.

Close up left side.

Close up right side.

I now have a long narrow "cavity" at the bottom of the window.

First, any idea what this stuff is? Someone ran out of stucco and had a bag of Plaster of Paris laying around? Bad stucco mix that sat on a shelf for years? What would make it soft and chalky like this?

I then went to another window next to it and did the same. I found some similar materials but only at a corner, not all the way across the bottom.

I have 26 more windows to check, I am not looking forward to do any more "digging".

Should I just mix new stucco and patch it? Mortar mix? I wonder if construction grout mixed to a soupy consistency would be a good application in this case?
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Old 12-14-17, 03:40 AM
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Join Date: Mar 2005
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I used to paint a lot of stucco when I lived in fla and I always thought that was damage from either neglected paint or caulking [water damage] You'd use stucco mix for the repair but it probably needs a bonding agent applied first to bind up the remaining chalk.
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