Leakage thru concrete condo exterior walls

[ajk1]

Has anyone ever encountered leakage thru reinforced concrte walls of condo tower i.e. from the exterior environment into the condo? I never before heard of such a thing.
It is claimed that this is the case in a 30 year old condo, and the condo oaord has an item in the reserve fund study to put a silicone coating on the exterior of the wall. That seems to me to be the wrong thing to do because silicone can trap water behind the coating (even though the silicone is caimed to be breathable, there is no agreed Standard for breathability).

 

[hokie66]

Sure, concrete leaks, but it is usually the horizontal surfaces which cause the problem. Has a study been done by someone competent in evaluating water ingress? Much more common than leakage through the concrete is leakage at joints, flashings, penetrations, etc. And just because the moisture shows up on the walls does not necessarily mean that is where it is entering.

 

[JAE]

Could it be interior condensation and not leaking?

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[oldestguy]

Consider some of the mechanisms by which water moves in porous material. A common cause is vapor pressure differences,usually by temperature differences. Moisture goes from warm to cold zones. In new concrete differences in chemistry create different vapor pressures. For instance salts usually attract water partly due to these differences.

 

[ajk1]

I take it from the answers to-date, that like me, no one has seen a concrete wall of a condo tower leak water from the outside to the inside, other than perhaps at a joint. Also, I take it that no one thinks applying a silicone to the entire surface of the outside of the wall (at a cost of $260,000) is a proper treatment (I don't; goes sgainst everything in my 55 years of experience).
Since vapour pressure moves the moisture from warm to cold (i.e from inside to outside, vapour presssure would not be the cause of leakage from outside to inside. I do not think a study has been done by anyone competent. Probably just a builder on the condo board who is reommending the silicone treatment. I don't know the details because it is a relative who is in the condo and he is asking me the questions.
The story he got is that there is some "spidering" visible on the outside of the walls in some locations. I take it they mean random narrow cracks. I think such cracks normally extend only a small distance from the surface (not thru the wall) and as such are not responsible for leakage.
I think the best advice I can give him is to get the condo board to retain a competent experienced engineering firm to examine and diagnose the issue and recommend a remedial measure, if there is really any leakage.

 

[DBronson]

ajk1:

There can be moisture movement from outside to inside through a wall. If the exterior is wetted from rain and then the sun heats the wall the moisture drive will be inward - especially if the condo unit is air conditioned and is cooler than the wall exterior. The board needs to consult a building science engineer such as Building Science. Link

Regards,

DB

NB: You're right about the silicone coating.

 

[ajk1]

Thanks.

 

[MotorCity]

In order to fix the problem, you first need to determine where the water is entering. While concrete is porous, water usually does not flow through concrete in any measureable amount that you are describing from a leak. Usually water only penetrates horizontal concrete members under hydrostatic pressure. I suspect the water is probably entering through a crack in the wall that may not be visible because of exterior or interior finishes. If there is a crack, I recommend Xypex or a 2 part epoxy pressure injection.

 

[ajk1]

I do not think that there are so many completely thru-the-wall cracks in exterior above-grade load bearing reinforced concrete walls that it would be a significant source of leakage, if at all.
The vertical load would tend to close any horizontal cracks (although one would not expect horizontal cracks since there is lack of restraint in the vertical direction and lack of horizontal load other than wind load). Shrinkage cracks in the horizontl direction would be relatively small because of lack of restraints in that direction.
I agree that if there are thru-the wall cracks that are leaking, that the solution would be to inject. I would inject with a urethane. Much easier to work with and more cost effectuive than epoxy.
But I have to twist myself into a pretzl to believe that there is significant leakageue due to cracks.
There are no covering materials on the exterior side of the wall, so any significant cracks should be visible.

 

[MotorCity]

I'd say that the odds of water coming through unseen cracks is far more probable than water pouring through a concrete wall like a sieve. Just another thought......is it possible that there is a leak in the roof and the water is running down the wall?

 

[jayrod12]

I'm with Motorcity. I'd bet the water is getting in somewhere above and travelling down the wall to wherever it is presenting itself on the inside.

 

[oldestguy]

It would be interesting to hear exactly what is present with photos or similar info. Where is it? Is the person complaining a "fuss budget" and not correctly and properly explaining the problem, if any? What kind of roof, windows or other possible entry places. Common wind direction and velocity?