NEW YORK (NYTIMES) - After the Sept 11 attacks, some landlords installed sturdy posts outside their buildings to guard against future strikes.

A legacy of the current health crisis? Kettlebells with handles made of copper.

Opting for the brown metal, known for its antimicrobial properties, instead of steel is among the steps some developers are taking to keep viruses out of their amenity spaces.

While slow to embrace major changes - some developers say they're hopeful that pandemics will not be a concern when their projects finally open in 2023 - developers are making tweaks in the face of the Covid-19 era.

They're adding cabana-lined roof decks, repurposing lounges as outdoor schools and switching out built-in couches for more movable versions to facilitate social distancing, as well as adding ventilation systems that are deluxe even by the standards of luxury apartments.

"We haven't had drastic changes," said Ms Whitney Kraus, the director of architecture and planning for Brown Harris Stevens Development Marketing, but added, "I don't think amenities will ever go back to the way they were before."

Some upgrades will likely appeal whether a disease is rampaging or not.

The residents of Astoria Lights, a co-op redevelopment in 38th Street in Queens, for instance, will probably enjoy a new roof deck long after the pandemic has passed.

After watching residents throng to an existing public roof deck after it reopened in July and noticing that units with private terraces at the Rowan, a nearby project, were hot commodities during the lockdown, the co-op decided to boost the complex's amount of outdoor space, said Mr John Petras, a RockFarmer co-managing principal.

The planned new deck will be the third at the buff-brick four-building co-op, which has 167 apartments, 138 of which are being converted from rentals in phases. One-bedrooms start at US$575,000 (S$786,600).

Plans for the deck, which will be presented to the co-op board for approval this fall, will offer about a dozen private cabanas, curtain-lined seating areas measuring about 100 sq ft with starting prices of about US$45,000 a pop. Putting them atop a pre-war structure won't be a snap. Mr Petras said "it's a major job and a major expense", about US$250,000 for the deck alone. "But there is a demand."

In fact, six of seven cabanas on the building's second deck, which had been planned pre-Covid and is about to be constructed, sold quickly, he added.

Quarantine has forced tweaks to other amenities. A planned basement co-working centre will now install dividers around workspaces to make them more private, while hammocks in courtyards will be similarly cordoned off. And a rooftop garden on the second deck has been redesigned to include walking paths.

"We're not going to go all in on protecting the building against pandemics, assuming they will keep happening," Mr Petras said. "But for now, we're doing everything we can."

Rental complexes seem to be rationing amenities differently. Gotham Organization, a rental developer at work on new projects, is undertaking a sort of test drive on some existing properties to see what works.

Properties like Gotham West in Manhattan and the Ashland in Brooklyn, for example, now require tenants to use an app called Amenity Boss - created this spring in response to lockdowns - to reserve their outdoor time in public courtyards, roof decks and terraces.

And when Gotham reopens its gyms this month, capacity will be limited to 33 per cent of what is permitted. Social distancing of 2m will also be required, which Gotham will enforce by unplugging some treadmills and other workout machines.

To make up for the reductions, Gotham will keep gyms open round the clock, said Mr Phil Lavoie, Gotham's chief operating officer, who added: "What can we do to allow people to enjoy themselves but also be as safe as they can be?"

Other apartment building gyms are going even further by imposing 20 per cent capacity restrictions, including Level BK, a 554-unit rental in Williamsburg, Brooklyn, from Douglaston Development, and Aro, a 426-unit tower in midtown Manhattan from Algin Management.

"You really want to be conscientious of the end-users at the end of day," said Mr Jeremy Brutus, a co-founder of Urbn Playground, which manages the gyms at both properties.

Mr Brutus said that since only about a quarter of a building's tenants ever use the gym, developers probably shouldn't spend endless amounts of cash on germ-free products. "Everybody is really searching for creative solutions right now."

One sparing-few-expenses example might be 378 West End Avenue, a 58-unit condo from Alchemy Properties that is under construction on the Upper West Side and will start sales this fall.

In the building's gym, Alchemy has opted for equipment with copper handles instead of steel ones, including barbells, dumbbells, weight machines and kettlebells, which are made by Black Iron Strength, a Washington state company.

Studies have found that the coronavirus can't survive as long on copper as on steel, although copper equipment can cost at least six times more than steel.

But Alchemy seems to believe in its antimicrobial properties. All doors in the condo's 11,000 sq ft amenity area, which features a half-basketball court, a squash court and a recording studio, have copper handles.

The developer is also emphasising air quality. The entire building uses hospital-grade Merv 13 filters, and amenity rooms will have an extra safeguard: a special ionisation system, tucked into ducts, that zaps viruses that might sneak through.

Similarly, key fobs unlock lobby doors, so no touching is required. Ms Kraus, of Brown Harris Stevens, said that motion-triggered faucets and automated toilets are also bound to be deployed in shared spaces soon. "Amenity spaces are prime locations to really embrace the current technology," she said.

Also expected in the next wave of apartment houses are common areas that can be easily sliced and diced. Expect new lounges to have multiple pocket doors, designers say.

At Bloom on Forty Fifth, a new 92-unit condo in Hell's Kitchen, developers Xin Development Group International and Kuafu Properties have chosen outdoor furniture that can be separated and relocated. Instead of long tables that seat eight, Bloom will now have side-by-side four-person versions, and long couches have been replaced with sectional sofas.

"We are simply adding some flexibility," said Mr David Chang, the associate broker at Compass handling sales. "Had we purchased these furnishings a year or two ago, it most likely would be more clustered and less modular."

Furniture is also a focus at Charlie West, a 123-unit condo in Hell's Kitchen from the firms Elad Group and Mi & Co, which is offering buyers a US$10,000 credit that can be spent to create one of the most coveted of amenities in this stay-at-home period: a dedicated home office.

Owners of studios can, say, spend the money on a special mirror that can fold down from a wall and double as a desk, according to Mr Andres Escobar, a senior partner of Lemay and Escobar, the designer of the condo's interiors. Or, the money can maybe help convert a bedroom into a full-fledged workspace, with lights, partitions, wallpaper, a large screen and a desk. Escobar's services are free; the money covers labour and materials.

Demand for home offices should outlast the pandemic, Mr Escobar said. "It will be kind of like having a fridge. You will have a home office."

Other changes are less physical and more programmatic. At One West End, a three-year-old condo from the Elad Group and Silverstein Properties with 246 units, 234 of which have sold, residents have repurposed a portion of a stylish sixth-floor terrace.

White couches where adults might have once sipped cocktails will be pushed aside to make way for socially distanced classes for children after their online-school day is through. There will be acting lessons and chemistry experiments, according to a project spokesman. When the weather turns chilly, the building might roll out heat lamps.

But as couches can be repositioned, and gym machines plugged back in, many of the Covid-era fixes will be short term, according to Ms Nancy Packes, the principal of Nancy Packes Data Services, which consults developers on projects.

Indeed, people may be scared to gather in amenity spaces today, she said, but they will likely pack them again soon.

"The immediate changes are just about concerns about transmitting the disease," she said, "but in the long run, developers feel that concerns about density will go away."