By Stephen Varone, AIA and Peter Varsalona, PE
I'm the board president of an eight-story cooperative in Brooklyn that's planning to undertake a facade restoration program, and we're wondering if we should include the balconies as part of the scope of work. Many of the balconies have cracks and stains, and some of them have what look like little icicles on the undersides that drip water. In addition, the metal railings are showing signs of wear, including some that are rusted and loose. Most of our balconies are covered with an artificial turf and have aluminum covers along the edges, so we're hesitant to rip up everything to do full-scale repairs if we can get by with fixing the loose railings and patching the undersides as needed until a later date. What's the recommended course of action?
If most of your building's balconies are in the condition you describe, the board will probably have to bite the bullet and undertake a full-scale balcony repair program. The defects you describe are significant, especially if they are widespread. Cracks allow water to penetrate the concrete, further damaging it and the underlying reinforcing steel. As the water freezes in the cold weather, the ice expands and creates more cracks, allowing more water to enter and causing more cracks and more water penetration—a cycle that grows worse with each freeze-thaw cycle.
The "icicles" are stalactites—calcium carbonate deposits (similar to the ones in caves) that form as water drips from the balcony slab, drawing out the calcareous materials used in concrete. Stalactites are a sign of substantial, long-standing water penetration, which could also indicate possible damage to the structural steel supporting the balcony.
The loose railings, which are a safety hazard as well as a code violation, are also a result of water infiltration. If the spaces where the railing posts penetrate the concrete are not properly caulked, or the caulking has deteriorated, water seeps in and eventually rusts the posts. As the metal oxidizes, the rust on the post accumulates and pushes against the surrounding concrete, loosening the posts from their footings and creating additional cracks, allowing more water to enter and furthering loosening the posts.
To determine how extensive the deterioration is throughout the balconies and what level of repairs are necessary, the first step is to hire a qualified engineer or architect to conduct a thorough survey. Working from a scaffold to fully access all the balcony areas, the engineer/architect will select an apartment line with balconies that show obvious signs of deterioration. Using a mallet to sound out the concrete, the engineer/architect will determine which areas are the most badly damaged and if the balconies are still structurally sound. Another sign to look for is ponding water, which indicates the balcony is not correctly sloped, preventing proper drainage.
As part of the survey, the engineer/architect may request investigative probes of the concrete (conducted by a contractor) to determine underlying conditions. In some cases, the engineer/architect may determine that a core sample—an approximately 4-inch-wide circular cut through the entire thickness of the concrete—needs to be taken. The core sample will be tested to determine the compressive strength of the concrete; it will also show the extent of damage through the entire thickness of the concrete slab. Investigative probes will determine if the steel reinforcement is rusted, which could lead to structural weakness. Keep in mind that to fully view the balconies' surfaces and conduct the probes, the carpeting and any other type of covering as well as the aluminum cladding will have to be removed.
Based on the survey findings, the engineer/architect will recommend whether a full-scale repair program is needed or if limited repairs will suffice. In your building's case, a balcony repair program would probably entail extensive concrete repairs and the installation of new railings. If the balconies are extremely damaged, they may need to be complete demolished and rebuilt.
While financially strapped boards may be tempted to hire a contractor to make spot repairs such as patching and caulking, the underlying deterioration in the concrete will remain and only grow worse. To properly repair the concrete, the defective areas must be entirely cut away. The cuts should be straight, not beveled or tapered, and the cut surfaces must then be scarified—i.e., given a rough texture by mechanical means—and a bonding agent applied so the new concrete properly adheres to old. If missing, a drip edge—a narrow groove several inches from the edge on the balcony's underside, extending the length of the balcony—should be made to help direct dripping water away from the building.
After the concrete repairs are made, a non-slip traffic-bearing coating system should be applied to the balcony floor and curb surfaces. A non-permeable coating system is applied to the balcony fascia surfaces, while a permeable coating is applied to the underside so the surface can breathe and allow water vapor transmission. Coating systems come in a variety of colors.
Ironically, sometimes repairing the concrete balcony floors and applying a coating system actually increases ponding. The paradox is caused by two factors. First, water that used to enter through cracks in the concrete now stays on the surface because the cracks have been repaired and the non-permeable coating system prevents water from seeping in. Keeping water from penetrating the concrete is desirable, of course, and the point of making repairs. The second factor, however, is if the balcony is not properly pitched toward the drain (usually located near the balcony door), water pools in depressions in the balcony surface. The remedy requires the application of a new layer of tapered concrete to attain the correct slope so that water properly drains.
Cladding is sometimes installed on new balcony curbs as an added protection, or on deteriorated concrete curbs in a misguided attempt to prevent further water infiltration. In some cases, aluminum cladding is even used to hold crumbling concrete pieces together. At best, the aluminum only temporarily blocks water. The cladding typically loosens over time, allowing more water in and trapping it, causing significant damage to the underlying concrete. Once repairs are made, the balcony edges should be left exposed.
Loose, rusted railings should be repaired or replaced depending on the severity of the deterioration. Railing posts will have to be removed from the concrete, and the defective concrete surrounding it cut away. It is recommended that the posts be inserted into stainless steel sleeves or sleeve openings that are then filled with epoxy. Sometimes a cushioned filler called backer rod, which is topped off with caulking at the base of the post penetration into the concrete, is used to keep water out.
If you're replacing the entire railing system, you may want to consider aluminum instead of metal. With a proper finish, aluminum does not rust and therefore requires far less maintenance than metal since it does not need to be regularly scraped, primed, and painted. New York City Building Code requires railings to be at least 42 inches above the finished surface on the balcony. If a layer of concrete has to be added to the balcony to achieve the proper slope for drainage (as described above), the new layer may reduce the height between the top of the railing and the balcony surface. The engineer/architect should account for this height difference when specifying the repair scope and railing design.
Since the building will be undertaking a facade restoration program, it makes sense to incorporate the balcony work as part of the overall repair program to avoid paying twice for mobilization and scaffold costs. The contractor will likely work on one apartment line at a time, so the board should have adequate time to give residents notice to remove all items from their balconies, including furniture, planters, rugs, personal items, etc.
As part of the repair program, the contractor may need to file an ACP-5 form to confirm there is no asbestos-containing material in the railing's paint or in the balcony's existing sealant or coating. You'll also need a work permit from the New York City Departments of Buildings, as well as a permit from the Landmarks Preservation Commission if your building is located in an Historic District.
Once the new repairs are in place, maintenance of the new balconies should be minimal. The caulking around the railing posts should be periodically checked and re-caulked as needed to prevent water penetration. Balcony drains should be kept free of debris, and residents should take care not to drag furniture or sharp edges across balcony surfaces as this could scratch and compromise the coating system.
Finally, residents should not cover their balconies with any type of carpeting, which traps water and keeps the balcony surface constantly wet, accelerating deterioration. Carpeting also hide cracks and makes maintenance more difficult.
There's no getting around it: A full-scale balcony repair program is a major undertaking, but it's one that should not be ignored. To preserve the safety and enjoyment of residents, it should be approached with the same level of consideration as other large-scale exterior projects.
Stephen Varone, AIA is president and Peter Varsalona, PE is principal of RAND Engineering & Architecture, DPC. This column was originally published in the July/August 2011 issue of Habitat Magazine.
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