Thread: Efflo on stucco

There is a lot of this efflorescence visible around the outside porches of today's house. It's way too consistent and too prevalent to be caused by a roof leak. Any idea how the moisture is getting there? It is all present on the inside walls of the patios and porches, not on the outside walls. The top of the parapet is pretty cracked, but then why would it only show up on the inside?

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Originally Posted by Jim Robinson

There is a lot of this efflorescence visible around the outside porches of today's house. It's way too consistent and too prevalent to be caused by a roof leak. Any idea how the moisture is getting there? It is all present on the inside walls of the patios and porches, not on the outside walls. The top of the parapet is pretty cracked, but then why would it only show up on the inside?

WAG.... It is showing up on the inside of the wall because it is sheltered from the sun and wind so it is slower to dry thus allowing the water to leach more salts out of the stucco. It could also be the way the wall is constructed and for some reason it is allowing the water to run towards the inside of the wall.

The sad news is that the only way to tell what is going on is to cut open the walls and take a gander.

My bet is on the cracks in the top of the parapet wall.

Originally Posted by Scott Patterson

My bet is on the cracks in the top of the parapet wall.

That would be my first guess too, then the fact that there are no weep screeds along the bottom to allow the moisture to migrate and weep out may be causing.allowing the moisture to migrate up the inside stucco.

The parapet wall, top and inside, along with the roof tie-in to the parapet walls, would be my first investigation (we already know there are no weep screeds along the bottom, no need to investigate that, just need to try to determine 'how much/how bad' the framing has rotted inside that parapet wall and that lower header section.

I often find problems with stucco "boxes". Especially in conjunction with a flat roof.

Effloresence is the symptom. The problem being is, any water that gets in can only rot its way out.

If that is an active scupper drain, quite a bit of water is being directed to that corner of the roof. That is the first place I would look.

My first thought from the first photo was poor workmanship. Look at the gap from ceiling to wall. I agree with the other posts too. Is the scupper too high allowing water to build up in that corner? The stain looks suspiciously high. I would like to see a drip of some kind at the inside corner but my instinct says water is dripping down from roof internally.

Definitely water entry, most likely from the scupper assembly-notorious for poor quality and design. Efflo is the least of your problems...