Trapped water that freezes and thaws is the number one killer of concrete balconies, so after the winter we've had, you might want to take a peek around your potentially precarious perch for some warning signs identified in the March issue of The Cooperator (article not yet available online).
Signs that your balcony has been H20-compromised include:
- Cracks, especially ones that have lengthened or widened since the last time you checked. (Like tracking suspicious moles, your property manager or maintenance staff should be doing an annual springtime visual inspection documenting and tracking any problems.)
- Rust marks and efflorescence, which is a powdery white substance that can form on stone and concrete and is a telltale sign that water is "migrating" through concrete
- If you noticed any icicles hanging off your balcony this winter, that's an indication that water is "working its way through and perhaps well on its way to causing cracks to form or expand."
- Flaking and pitted concrete surface, and something called "spalling," which is oxidation of the reinforcing bar buried in the concrete
- Wobbly railings, which may mean the posts are corroding because they weren't protectively coated before being set into the concrete
With good annual maintenance that includes sealing cracks, concrete balconies can last 50 years, one expert tells the Cooperator. "And on the other hand, the balconies on some buildings built five years ago need to be completely restored." Risk factors include poorly constructed balconies where the developer skimped on concrete. Balconies exposed to carbon dioxide from heavy traffic may also be more vulnerable.