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My home was built in 1914 (Portland, Oregon). In 1948, the house was moved 200 feet to its current location. The 750 square foot house has a concrete basement with a concrete floor. The concrete basement walls are approximate 7 feet tall.

A view from the inside of the basement shows the concrete was poured in layers. Some of these layers are crumbling. 1/2 to 1 inch aggregate is falling from the wall. Other layers are in great condition.

Interior and exterior "tapping" with a screwdriver reveal most of the the concrete is solid - even though the aggregate can be seen in some areas. Other areas sound hollow. This is where the aggregate will crumble from the wall.

The exterior has a skim coat, but half of it has fallen off, or is ready to fall. Again, other exterior section where the skim coat remains appear and sound solid.

Questions:

  1. What is happening to the concrete?

  2. How can this deterioration be stopped?

  3. Does the concrete need to be replaced?

  4. What type of trades person should look up to make the repairs?

exterior interior

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  • Without more pictures, I would say this looks like this foundation wall was underpinned. Not a bad thing, the single picture really does not tell the whole story... If it was underpinned, why would they build/pour a foundation wall, then underpin it and then set the moved house onto it, curious...
    – Jack
    Commented Dec 24, 2014 at 7:28
  • I suspect water got in behind the thin layer then froze and broke it. I would remove all of the thin layer then cover the concrete with some other type of siding, wood or vinyl. Or sand and paint it.
    – Ariel
    Commented Jan 6, 2015 at 11:37

3 Answers 3

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Concrete will deteriorate over time depending on the mineral content of the soil that is in contact with the concrete. Removal of the entire pour is not required or recommended. This would be costly and time consuming. The areas that sound hollow will have to be removed. These areas act like a cancerous pocket and will harbor the moisture that is partly causing the deterioration.Steps to consider:

  1. Remove all hollow sounding areas with a pneumatic chisel hammer. (small one would be better).
  2. Retrofit some rebar into the areas removed into the good concrete and set with epoxy.
  3. Reinforce your basement with new shotcrete concrete.

Note: you will be tying into your existing concrete with new rebar and epoxy. Then set some screte boards to the depth of the new shotcrete wall thickness. Then you will be ready to hire a contractor who will apply the shotcrete with a pumper. You might want to contact a structural engineer to confirm this course of action... Good luck.

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Being a concrete cutter, I personally would Remove and do a proper pour. The current concrete looks hand mixed and poured at different times with different aggregate... It will only continue to get worse, if its structural definitely replace it with modern concrete. Quite a expensive job.

If its structural You can shore up everything very easily, demo old concrete and get a proper pour.

Or do the pours in sections so nothing has to be shored.

Or make it look pretty and cover it like any normal person would do.

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  • That's quite an expensive process for some deteriorating concrete. Hell that might cost more than the house... I think slowing down the deterioration is a good option for the home owner.
    – DMoore
    Commented Jan 8, 2015 at 21:42
  • I guess. Concrete is my thing, cost should not be an issue if its structural. It will eventually shift and fail. Patch it, go ahead it will look pretty but concrete is porous.. So your patch will crack off within a year if your in a cold zone with freeze thaw cycles.
    – Russell
    Commented Jan 8, 2015 at 21:54
  • Furthermore a good foundation is the key to a lot of things in life.
    – Russell
    Commented Jan 8, 2015 at 22:02
  • @Russell and how do you mean "demo old concrete“. Old concrete is supporting the whole house. What would take the load once you demolish concrete? Supporters? For the whole house....I don't think so. Not even if you do it partially.
    – python starter
    Commented Apr 11, 2015 at 18:54
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I think that you should call an experienced mason to come and have a good look at it all. There are too many variables at work here, and a foundation is too large (and important) a structure and system to summarize with a few photos and a brief description. I don't know that you're going to get a helpful or realistic answer from us.

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