I am having a problem with a section of cement block foundation.The house/foundation is approx. 50 yrs. young.The problem is the interior surface (in one particular area) seems to be deteriorating slightly. i would like to fix before it goes to far. The foundation was painted (interior) with drylock 13 years ago and is flaking taking the surface of the block with it. The problem, i dont think, is do to moisture/water infiltration from the exterior. the specific area is at a gable end a exterior grade slope pretty well away from foundation ;also exterior foundation is in pretty good shape.Is the problem the drylock?How should I treat the problem& repair so I have no further issue?
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Replies
Sounds like it could be efflorescence. Do you see any white salt like deposits under the paint or on back of the chips? Is it haydite block? What do you mean by it's taking the surface with it? Is the block spalling? Or is it the joints?
With block walls, you can't rule out moisture because of the location.
Hey Barry,
I would say it is a spalling situation.The joints are not any different than the face of the block.Seems like some minor block surface is deteriorating under the paint surfase.????What is hayite block???
Haydite is a light weight cement block, looks more porous than cement block.so you don't see any white chalky substance? Anything else going on in this area? Dryer or bath vent? plumbing?
Barry E-Remodeler
No,definately not haydite block,Nothing else going on there either.A simple foundation wall.An outside sillcock penetration through sill above,but shut off for winter at ball valve downstream.It would be quite obvious if it were an issue.As far as efforesence,Possibly a small amount.Tough to tell,because of white colored drylock paint on surface.I guess my main concern is how to prep,reseal,repair,etc. block face to prevent a reoccurance.Barry,I really appreciate your input & obvious knowledge of this problem!
Can you take a picture? Normally, it it was efforesence, I would say find the source of the moisture, get rid of it then fix the paint. That involves scraping, wire brushing and/or sanding. Then I would spot prime with an oil based primer or masonry sealer and topcoat with 100% acrylic .The block could be getting water from somewhere above or even below the floor. The cavities in the block could be holding water. efforesence usually requires moisture and even spalling usually requires moisture and a few freeze/thaw cycles.Was the drylock used because of a problem originally?
Barry E-Remodeler
An outside sillcock penetration through sill above,...
My guess is that is where the moisture is coming from. Not a leak in the plumbing, but at the penetration point of the sillcock.
Barry and Mike are correct. Efforesence= water from somewhere.
Wipe your bare hand over the surface that is spalling. If it comes away with a chauky residue, it is the mineral salts in the block being leached out by water entering the block.
Stop the water intrusion, then clean, prime and paint the area.
Dave
Hmm. You say you don't think the problem is moisture. In my experience, these sorts of problems are ALWAYS due to moisture. I'd suggest you assue this IS a moisture problem, and look for possible ways that could happen and how to eliminate it. Dirlock itself will not deteriorate concrete. What it may be doing is keeping moisture that is accumulating inside the block from escaping.
Mike Hennessy
Pittsburgh, PA