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I presented this problem for discussion a while back but we still haven’t been able to resolve it.
A traditional 2 or 3 part stucco application was placed on a brick facade structure – no lath or metal cornerbead evident – in both the 1940’s and later as repairs or patches or just completing the job in the early 1970’s. Brick is single wythe with air space over diagonal 1x sheathing, built in 1913.
The final coat is what is, in many, many places, turning to a fine, white expansive powder which is causing the building to look like it has cancer and is bubbling and cracking off the paint. The underlying brown or scratch coat does not appear to be affected at all. Some areas appear to have been patched, other areas appear to be original. There is no obvious external cause. The damage is occurring under cover, in the open air, with or without rain or sprinkler exposure and also inside the house at large passage to an attached sunroom. Don’t know if this was an opening to a rear porch before the sunroom was added. There are no drainage problems that we can find. This problem has, according to the owner, only been escalating within the past year or so.
Any ideas? Or do we just chisel off the offending parts and reparge, hoping it lasts?
Replies
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Hey Ralph,
The condition you describe is called efflourescence, and occurs in concrete, plaster, brick and block - where ever lime in cement reacts and forms salts and bleeds through to the surface.
Can't say what's causing it, of course, w/o an inspection, but it DOES require some amount of moisture to occur (it's often seen on retaining walls and stucco near the ground behind planters and landscaping bushes, etc.). The fact that it's also evident on the interior wall leads me to think there is a roof joint at the sunroom or roof penetration somewhere that is allowing just enough water to seep down inside this wall. So keep your eye out for that - could even be a vent stack or something that needs a better seal, and water runs in, travels across a rafter or joist, and comes down at this wall - while actually penetrating your roof several feet distant.
Wash the wall, or broom off the excess powdery substance. Prepare about a 0.5% solution of muriatic acid, available at masonry yards or possibly Home Depot. Paint stores that sell to contractors may have it - Dunn-Edwards here did last time I needed some.
Use a Hudson sprayer (or other garden pump sprayer) and soak the offending areas. It's going to bubble as it reacts w/ the alkyline wall - that is a neutralization taking place. Keep that inside room well ventilated. Rinse w/ water - well, inside you can't rinse much, so use a weak solution, even if you have to repeat after it dries.
Get yourself a product called UGL. It's like a paint, but only covers about 50 sq. ft. to the gallon. It blocks efflourescence, as well as sealing water penetration from the negative side (outside) of a wall or retaining wall.
We've seen a lot of this in the past, and have had excellent results using this inexpensive fix described here. Good luck.
Geo.
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I presented this problem for discussion a while back but we still haven't been able to resolve it.
A traditional 2 or 3 part stucco application was placed on a brick facade structure - no lath or metal cornerbead evident - in both the 1940's and later as repairs or patches or just completing the job in the early 1970's. Brick is single wythe with air space over diagonal 1x sheathing, built in 1913.
The final coat is what is, in many, many places, turning to a fine, white expansive powder which is causing the building to look like it has cancer and is bubbling and cracking off the paint. The underlying brown or scratch coat does not appear to be affected at all. Some areas appear to have been patched, other areas appear to be original. There is no obvious external cause. The damage is occurring under cover, in the open air, with or without rain or sprinkler exposure and also inside the house at large passage to an attached sunroom. Don't know if this was an opening to a rear porch before the sunroom was added. There are no drainage problems that we can find. This problem has, according to the owner, only been escalating within the past year or so.
Any ideas? Or do we just chisel off the offending parts and reparge, hoping it lasts?