Outdoor spaces like balconies, terraces, and roof decks can add a lot of charm and value to your building, as well as providing pleasant spots for residents and their families and guests to take the air and relax. It's just about now - as residents are bringing in plants and re-caulking windows - that co-op owners and boards should consider fixing up balconies and rooftop living areas. While most work should wait until warmer months because of materials' reaction to cold, planning early could save money.

Scheduling work for spring now can help co-op boards secure good prices, while guaranteeing work for construction and repair crews at the beginning of the busy season. Also, preliminary site work can be done during the winter months, often at off-season prices. Planning early also allows for comparison-shopping and eliminates last-minute decisions. Industry specialists say too many property owners don't do their homework before spending.

Outdoor living space considerations range from the practical (is the balcony about to collapse?) to the aesthetic (should a greenhouse be added to the roof?) But basic safety should be the first concern.

"The repairs of these are typically expensive, noisy, dusty and inconvenient for the shareholders. And - like with dental work - most people don't take the steps they need to take, until they must," says Wayne Bellet of Bellet Construction in Manhattan. "Most people do not do preventative work"¦which is why I'm so busy."

Every five years, a general, exterior safety inspection must be completed by an architect or engineer and filed with the city Department of Buildings (DOB). It's called Local Law 11, and most high-rise building in New York City fall under its jurisdiction.

"But if there are any suspected conditions, that doesn't mean you can leave them for four years and 364 days," says R. Neal Eisenberg, preservation and restoration consultant to Garden State Commercial Services. "The buildings can be heavily fined or even closed, if they do not comply. It's an unusual law, and there are very few municipalities that have a law as strict as New York City."

The first problem regarding outside spaces is deterioration. And the first step to finding signs of deterioration is looking for them, Eisenberg says. On balconies, for example, owners should look for cracks, rust stains, salt stains or any discoloration in the roof or floor. These are signs that something may be wrong. The metal helping to support the balcony may be rusting, or water may be deteriorating the slabs.

According to Eisenberg, the best thing is to watch the discoloration or cracks for at least six months. If the cracks, for example, aren't very large and aren't getting bigger, there may be no need to worry. Maybe there was a problem with the construction of the balcony, but the balcony isn't at risk of further accelerated deterioration.

If an owner suspects there might be structural damage to their balcony or terrace, they should bring the issue to the board or managing agent's attention immediately. To verify the problem and assess the balcony's condition, the board might then consider calling in a specialist to inspect the spot in question and offer some guidance toward repairing it. Employing a quick fix and just covering a balcony with an outdoor carpet is not a good option. It only masks the problem, and can make it worse by locking moisture under it. The same can be true of some paints and water sealers. Some surfaces have been treated with an almost invisible sealer that may not react well with other products. Or, the surface may need to "breathe." Tiles can be good, but they need to have proper drainage underneath. If not, they, too, will lock moisture under them and cause some catastrophic problems.

Balcony railings and rooftop barriers can be doubly troublesome. Rusting or loose railings should be checked for further deterioration, just as balcony slabs are. Sometimes there's just a loose screw that needs to be tightened, but in extreme cases railing may need to be replaced.

Nationwide, about 140 children under 15 years old die each year due to falls of some kind, according to the American Academy of Pediatrics.

"In some urban areas, falls have represented up to 20 percent of the deaths of children from unintentional injury, as compared with an average of one percent to four percent nationally," reports the Academy.

New York City doesn't have a single set of building regulations regarding, for example, the height of roof walls. It can depend on the age of the building, the use of the outdoor living area, and the access needed to the roof from neighboring buildings.

"There are requirements for guard rails and stuff like that, but it really depends on what you're doing," says Ilyse Fink, spokeswoman for the DOB.

"Our advice is always consult with an architect [or engineer]," she says. And as a general rule, "if your building wasn't built for that, you're not supposed to [do it]. Your roof was built to be a roof"¦.You want to make sure that if you have 100 people on that roof, your roof can hold that."

According to Fink, most roofs have parapets - short walls bordering the edge of the roof. "In an older building, [the parapet] might be only two feet," but if the owner changes the roof to a rooftop garden, often a 42-inch wall is mandated. That can be achieved by just putting a fence on top of the parapet.

"In most cases you can do something like this, but there may be cases when you can't," Fink says. For example, exits must not be blocked and some roofs must be accessible from other rooftops. The roof itself, though, should be the first concern. Often, it's designed to withstand the weight of a single person, but not the weight of many people or even a bunch of potted plants.

"Roofs can be punctured or disrupted fairly easily," Eisenberg says, adding that, "Some roof materials can be disrupted by the weight of the footprint." Generally, people should not walk on the roof itself. Instead, stones or other material should be put down.

Fifty years ago, roofs were made with layers of asphalt. Then came plastics and other materials. According to Eisenberg, a lot of people have gone back to the asphalt-layer roofs. They're cheaper and, if the roof won't be used as a living area and won't be exposed to extreme hot and cold weather, they often are fine.

For entertaining, the so-called "upside down roof" is popular, says Eisenberg. In this model, the roof membrane is applied directly to the roof structure. Insulation board and then gravel or another stone substance more appropriate for walking on is put on top of the membrane. The biggest problem with fixing leaks in upside down roofs is finding the leak in the first place, since the roof membrane - usually the layer of the roof exposed to the air - is buried.

Another roof danger isn't as obvious: It's those good-looking plants. They need good drainage, or water will collect under them, causing the roof and building to deteriorate.

Eisenberg remembers a project in which the roof had built-in planters, but the drainage was never considered. Muddy runoff from the planters drained into the building, causing extensive damage to the top-floor apartments and (understandably) infuriating the occupants.

On another roof, there were vent pipes, which isn't unusual. "All buildings have various devices to allow the venting of gases and vapor from the building and these vent pipes usually come though the roof," says Eisenberg, but in this case, "The superintendent spruced up the roof by setting plants in the vents. He actually could have caused an explosion in the building."

According to Bellet, "Most planters today have built-in drainage. The manufacturers have thought all that through for us"¦It's terribly simple - but it can be expensive."

If the plants are going to be in a greenhouse, things get more complicated - not necessarily because of drainage, but because of the law. A greenhouse technically counts as an indoor living space, and each plot of land is allowed only so many square feet of it.

"You're only allowed to build a certain amount of rooms, under the zoning laws," says David L. Berkey of Gallet, Dreyer and Berkey, LLP, a Manhattan-based law firm that handles construction cases. "If it's enclosed and it's heated, or it's air conditioned and built semi-permanently, then it gets counted. If it's open to the elements, it's not counted."

There are other things to consider when thinking of rooftops: Pigeons, for example.

A wire barrier - with needlelike points at the top - is one of the most popular methods of deterring birds. The birds won't rest there, says Bellet, and the wire tends to catch flying feathers and fluff, preventing it from entering the building's ventilation system.

There are also humane services that will catch the birds and then release them elsewhere. Such measures are expensive - and forget about hanging faux-owls or hawks all over your rooftop to discourage the feathered fiends; pigeons don't fall for them any more than they do those cutout cat silhouettes with glass marble eyes.

According to Bellet, "The answer is, there is no way. There is no legal, permanent way," to be rid of pigeons. "It's an exercise in patience and money. Or you could hire real owls."

Lay some attractive gravel walkways, set out some plants, get rid of the pigeons, and more residents will flock to your roof deck"¦or not. If your co-op is considering opening up the roof, professionals agree that the first thing to do is to toss the idea around among shareholder/owners and then start to talk to contractors. According to some contractors specializing in terraces and roof decks, a lot of people don't use roofs, even after they're finished for traffic.

The possible exception to that may be people living on the highest floors. Some leases give roof rights to penthouse owners, though roofs are generally a common area. If the roof is the domain of the penthouse occupants, the penthouse owner needs to clear away the plants and furniture at his own expense if, for example, the roof needs work, says C. Jaye Berger, a Manhattan co-op and construction attorney. If the roof is a common area, Berger recommends adopting rooftop rules. They might address hours, use of alcohol, number of people allowed at one time, and noise.

Sometimes, penthouse owners negotiate to simply buy roof rights. "I see more and more of that," Berger said. "You're in effect buying more shares. There has to be some kind of appraisal that's done." Potentially, roof rights can include air rights, though not necessarily, since air rights might not exist for the property.

"There's not really one best material or procedure out there," says Eisenberg. But that's a reason to do more research into available options, not less. "Too many people want to fix something before they know what's happening."