I'm looking to buy living quarters in this basement level apartment. The only doubts I have are because some ~5 years ago, there was a giant flood in the city and had this building been couple blocks down the road, the basement would have been underwater.

Now there is already good ventilation from the common system on the roof of the building, there are no windows and I'm planning to install a heavy duty water proof door. All that remains is the concrete, the apartment is basically a concrete box all over, I looked around and didn't see any cracks or crevices but how likely is it that the entire 62m2 worth of concrete wall, floor and ceiling is completely water proof?

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    Very unlikely unless the entire exterior surface was waterproofed during construction. – bib Sep 5 '14 at 19:22

Concrete on its own is a porous material. It may slow water down, but will not stop it. It is possible that the outside of the wall is waterproofed, but it's not a guaranteed.

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Concrete on its own might migrate some moisture, but can be used to create water tanks. Cracks however are not waterproof, and it's certain that your basement has some.

Your concerns should resolve around humidity, mold and ongoing dampness, not overt flooding. And of course you'll need some video picture frames to compensate for the lack of windows.

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  • hah, the no windows part is what attracted me in the first place, I'm a kind of mole man like that. The majority owner of the building assured me that dampness wouldn't be an issue thanks to the ventilation – Jake Freelander Sep 6 '14 at 8:59
  • Get little USB key humidity meter and leave it down there for a week. And without question a 24 hour or 48 hour radon gas test. – Bryce Sep 8 '14 at 8:00

The issue is not the water-proof qualities of the concrete, it is the flood-proof status of the building. That status is largely a function of location. If flood water rises to the level of the second floor, the basement of just about any building will be full of water regardless of how it is constructed.

General practice is to treat floods as statistical events - i.e. there are 100 year floods, 10 year floods, 500 year floods, and the floodpocolypse. Historical or archeological records, if available, are one way to assess the risk. Competently prepared flood maps are even better when they are available.

But in the end, it all boils down to a flood risk assessment. Flood insurance is something you may want to investigate. Rates will reflect an actuarial evaluation of the risk.

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