Thread: Spalling basement walls

1950's home with basement interior and exterior exposed foundation walls spalling like crazy.
The outside has been covered with a plastic brick covering and basement walls have been covered with what looks like pitch or car undercoating.(that s--t will stick to anything!)
No brainer to improve drainage away from foundation.
Anyway approx 6 inch thick walls and parge coating is separating off of walls.
Even though there were no vertical or horizontal cracking seen on any walls, I told client it still is a major defect based on cost to try and repair the wall system. The fact that the parging that has been done was done poorly and the addition of the black covering further complicates the repair. Does not seem to be the easiest DIY project. Walls solid and vertical just peeling badly.
I would appreciate further opinion on condition and how to report.

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In my reports, I state that spalling was found to the surface of the concrete at various areas (occasionally, I will be more specific, if just in one area) and then describe what spalling is. Then I go on state that it has likely been caused by inadequate/improper drainage. I prefer to use "likely" in the event a foundation contractor disagrees as to the cause. Then I defer to the appropriate trade/contractor.

I think you've got it pretty well covered. The concrete is degrading above ground and there is probably a history of moisture getting into the basement.
That is serious deterioration for 60 year old concrete. It is big trouble, IMO.

Based on the pictures, the general condition of the concrete indicates "it is beyond repair." The matrix appears to have lost its integrity, caused by any of several possible reasons. Concrete can be properly repaired only if the base material is reasonably sound and solid, after all of the deteriorated portions are first removed. The pictures don't indicate that is likely to be the case. The only way to accurately determine what's causing the problem(s) is to take a core sample and have a qualified materials lab perform a spectroscopic analysis.

If I were to guess based on what's visible, I'd say either carbonation of the mix, or possibly contamination by the use of improper set-accelerants, or even alkali-silica reactive aggregate. Home inspectors aren't supposed to guess, so the safe path forward would be to call for further evaluation by qualified parties.

Complete removal and replacement of the foundation is probably the only real solution, at significant cost. And usually only practical for high-end homes worth saving.

Hydrostatic pressure pushing the inside facing off.

Also a concern with off gassing of interior tar like substance.

With regards to the interior basement walls: This is why it is a bad practice to apply a vapor or moisture barrier of any kind on the interior side. They need to have a way to dry! No matter how water proof you try to make the outside, moisture is going to get into that wall and it needs to dry from the inside.

I'm also seeing this spalling behind the vapor barriers installed in (mostly newer) Crawlspaces. The newer, highly touted way of installing vapor barriers in crawlspace floor and walls and eliminating Crawlspace ventilation....I believe, will be rethought after the lawsuits start coming in, my guess will be within the next 5 years. A vapor barrier on the crawlspace floor is a good practice, but the walls? I don't think so.

The Bridgeman seems to have reasonable guesses as to the underlying causes of the concrete deterioration.
It looks bad allright. I think 'spalling' is only scratching the surface of what is going on with this concrete. The original concrete mix, pour and placement of the concrete is in question - there appear to be big chunks of aggregate - and material that is deteriorating - far more than just a drainage problem to have caused.
I think the mix was wrong from the get go.
I have seen old foundations around here with the large aggregate rocks which could be easily pulled from the concrete which was turning back to sand. Not much strength there to support a house. So, if an event like a geological shaking should occur, the sand pile below the house will make for a nice soft landing.