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Preparing Your Building for Winter

By Stephen Varone, AIA and Peter Varsalona, PE

I'm on the newly elected board of a Jackson Heights cooperative, and at our most recent board meeting we discussed what we should do to prepare the building for the winter. The previous board replaced the roof three years ago and repaired the few minor items found during the last Local Law 11/98 facade inspection. The property has been properly maintained overall for the most part, but what items should we be looking at to ensure that the upcoming cold season doesn't cause any preventable problems?

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Boiler maintenance includes checking flue tubes for leaks and clogs and treating the water to inhibit rust and corrosion.

Although there's not a way to completely "winterize" a building as such, it does make sense to make sure that everything is watertight and in proper operating order, and that vulnerable spots are addressed before the cold sets in. Winter is particularly hard on buildings suffering from water penetration because the trapped water expands as it freezes, causing bricks and masonry to crack, spall, and loosen. The best prevention from these types of problems, of course, is to follow a regular year-round maintenance program as your cooperative has apparently been doing.

Not only should the exterior envelope of a building be tended to before the onset of winter, but it's also a good idea to address key elements of the mechanical systems. Below is a basic checklist of items that every board member and managing agent should go through to prepare a property for the winter season:

Building Exterior

Caulking: It's such a simple maintenance item that it's often overlooked, yet it's the first line of defense in keeping water out of buildings. While properly applied caulking materials are expected to last 10 to 20 years, caulking still needs to be checked at all junctures and installed or replaced where it's deteriorated or missing. Key locations are joints between coping stones on top of parapet walls, around through-wall window air conditioner sleeves, and around windows and doors.

Roof: No part of a building receives as much direct exposure to the elements than the roof. Therefore, a general roof inspection is recommended every fall and spring. Potential problem areas are all penetrations through the roof, such as stack vent pipes, ladders, and drains; open seams on the roofing membranes; blistering or cracking; ponding; base flashing that has slipped or peeled away from parapet or bulkhead walls; deteriorated counterflashing; and broken glass, nails, screws, or other debris that could puncture the roofing membrane. Pitch pans surrounding roof penetrations should be filled to the brim with an appropriate sealant. Some roofing systems may have a reflective coating, and if it is worn in spots, the exposed areas of the roofing membrane are exposed to ultraviolet light, accelerating deterioration.

Drains, another basic but often neglected item on roofs, should be checked for clogs, and debris built up around the drains should be cleaned as necessary. For roof decks with pavers, the pavers around the drains may need to be removed to see that there are no leaves, paper, sand, or other items blocking them. If a lot of debris has found its way under the pavers, large sections of pavers may need to be removed by a contractor and the underlying roof surface cleaned. Gutters, leaders, and scuppers should also be looked at to make sure they are not loose and are cleared of leaves and other debris so water can properly drain.

Facade: Any major problems on the exterior should have been repaired during the most recent Local Law 11/98 cycle if the building is taller than six stories. But if the building is six stories or less in height, or if its last Local Law 11/98 repairs were a few years ago, at the minimum a visual exterior inspection should be conducted using binoculars to check for loose, spalling, or missing bricks, stones, mortar, masonry, terra cotta elements, cornices, windowsills, balconies, railings, etc. Of particular importance are areas that stay wet after a rainstorm, which may mean cracks, deterioration, and/or other defects that may be allowing water to infiltrate.

Windows: If a draft is felt around the windows or the panes are cold to the touch, the windows may need to be replaced with better-fitting thermally insulated double-pane units. As a stopgap measure, removable foam insulation can be installed around the window frames and a plastic film applied to the panes.

Air conditioners: Ideally, to keep drafts from entering, residents should remove their window-mounted air conditioners before the cold weather sets in. But for residents who decide to leave their units in, they should wrap the inside and outside (if accessible) with insulated covers, panels, or plastic sheeting and tape along the edges where the unit fits into the window.  Through-wall units, which are not removed, should likewise be covered inside and outside and caulked along the sleeve's exterior perimeter.

Chimneys: Chimneys are used more in the winter than in other times of the year, but many are not inspected and cleaned as often as they should be (at least every five to 10 years). Over time, flues can get clogged with combustion debris and bricks and terra cotta. The flue should have a draft inducer or fan on top to draw out fumes, and the variable-speed-controller that operates it also needs to be checked periodically. The damper should be opened and closed to make sure it moves freely.

Terrace faucets: Some terraces and roof decks have a domestic water tap for watering plants or hosing down surfaces. When the temperature drops, the inside valve for the plumbing line should be shut off, any remaining water drained, and the faucet covered to prevent water from freezing inside, which could cause the pipe to burst and crack the surrounding brick and mortar.

Site exterior: Cracked or uneven pavement on pedestrian pathways is a tripping hazard, and the cold weather will cause the pavement to crack and expand even more. Repairs should be made before troubled spots get worse. In addition, keep courtyards and drains clear and free of debris.

Mechanical Systems

The last thing residents need is a sudden shutdown of heat on a cold January night. Boiler and heating system items should be addressed well before the cold weather sets in so everything is ready to go when winter begins.

Boilers: The boiler flue tubes, over which hot water or steam passes, should be checked to make sure they are not leaking or clogged. A basic check of the insulation around the boiler piping should also be conducted. Most boilers require some type of chemical treatment to inhibit rust and corrosion. A heating contractor will add the chemicals before the heating season and then once every month or two thereafter.

As part of its maintenance contract with a heating contractor, the building should also have the boiler's flue checked to make sure it is clean and not blocked or partially collapsed. If the boiler's combustion gases cannot freely exit through the top of the flue, they may diffuse to apartments or other building spaces, creating a hazardous condition.

Burners: The heating contractor should also conduct a test to determine the burner's combustion efficiency. Maximum efficiency for common Scotch-marine boilers is approximately 85%; 80% or less is too low and will burn more fuel. Burners with low efficiency levels will have to be adjusted. The oil transfer system and oil preheating system are also part of the contractor's checklist.

Radiators:  A common resident complaint about radiators is the loud banging. The noise is caused by steam coming in contact with cooler water (condensate), creating a rapid expansion of the condensate water in the pipes. Radiators in prewar buildings typically have just one pipe shared by both the steam and condensate. Single-pipe systems rely on the pipe's downward slope to return water back to the boiler for heating back into steam, but in aging pipes the condensate can get trapped in elbows and sags. When steam hits this trapped condensate, the hammering sound is created. The pipe may have to be repositioned or replaced to eliminate the banging.

In a two-pipe system, one pipe is used for steam supply and another for condensate return. A steam trap at the bottom of the radiator expands when steam comes in contact with it, blocking the steam from exiting the return pipe. Operating like a diaphragm, steam traps expand and release thousands of times in a heating season, so the element will eventually fail. When a radiator remains cold even as steam is flowing to it, it could mean the steam trap is no longer working and needs replacement. Air release valves on the side of the radiator should also be checked (they should hiss as steam enters the radiator) and replaced as necessary.

Cooling towers: Buildings with central chillers, heat pumps, or fan coil units use rooftop cooling towers to reduce the temperature of the condenser water circulating through the system. Many properties shut down their cooling systems around October 15, at which time New York City buildings are required by law to provide heat. Supply valves are closed off and drain valves opened to remove any leftover water in pipes to prevent freezing.

Some heating and cooling systems, however, operate year round. For those systems, the water in the cooling tower must be kept from freezing either by adding a glycol-based fluid (antifreeze) to the water or using immersion coils that heat the water. Wood tanks used only as a fire standpipe supply (with no domestic water) also need immersion coils to keep the water from freezing. The building's maintenance staff or a mechanical contractor can provide these checks.

Brick Vents: These vents on the facade of the building bring in fresh air from the outside for fan coil units used to cool apartments in summer. During the winter, when the fan coil units are being used for heating, drafts can enter if the dampers to the vents are not shut or sealed.  The dampers, however, can be tricky to access: The cover may have to be removed, and a hard-to-reach lever pushed or pulled. For dampers that are stuck or do not close all the way, removable foam insulation can be inserted around the edges of the unit as a temporary measure.

Outdoor piping: Cold water pipes running to and from a rooftop water tank or cooling tower are often heated using an electric coil, known as heat tracing, wrapped around the pipe to keep the water inside from freezing and the pipe from bursting. A layer of insulation is wrapped around the heat tracing, which is plugged into a ground fault circuit interrupter (GFCI) on the roof. A routine roof check should include making sure the heat tracing is plugged in and none of it is exposed because of insulation that is worn away or missing.

Many of the above items, such as routine checks of roofs and electrical connections, clearing drains, caulking, wrapping through-wall air conditioners, etc. can be performed by building maintenance staff. Other more specialized tasks, such as boiler and flue inspections and cooling tower maintenance, will require calling in the building's heating and cooling contractor. Your board may also want to call on the trained eye of an engineer or architect to provide an overall look at your building on an annual or semi-annual basis and identify any potential trouble spots, especially ones that may become more vulnerable during a harsh winter season.

Stephen Varone, AIA is president and Peter Varsalona, PE is principal of RAND Engineering & Architecture, DPC. This article was reprinted from the December 2007 issue of Habitat Magazine.

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