During his house hunt, social media consultant Jonathan Rick discovered what he thought was the perfect condominium in Arlington. The new building offered a pool, a gym and a concierge and was within walking distance of stores and Metrorail. The two-bedroom, two-bathroom unit for sale had a den and a balcony and was on the quiet side of the building.

But while touring the condo, Rick heard loud sounds coming from an air-handling unit in a closet close to the kitchen. “I brought in a technician to recommend ways of reducing the noise, but the amount of work and expense involved was off-putting,” he says. “I decided to buy a condo in another building where the equipment is located in the hallway outside the unit.”

Condo infrastructure — hard-to-change components such as heating and cooling equipment, demising walls, windows — can be a deal-breaker for buyers. But too often, these elements are overlooked in making purchasing decisions.

“Condo buyers usually aren’t too engaged with the engineering of properties they’re looking at, unless they’ve had a previous experience that left them with a heightened awareness of particular concerns, like noise from the unit above,” says Morgan Knull, a broker with Re/Max Gateway in D.C. and Arlington who sold Rick the quieter condo last year.

Even when buyers ask about potential problems, Knull says, most listing and selling agents can’t supply the technical information about construction unless the sales contract or disclosure is specific about building materials and systems.

In D.C., sellers are required to supply a property disclosure statement indicating the condition of mechanical and structural components and appliances. Virginia and Maryland permit the seller to furnish either such a disclosure statement or a disclaimer statement, in which a seller is obligated to disclose only existing and known defects. “Nearly all sellers in Virginia disclaim,” Knull says. “In Maryland, some disclaim and others disclose.”

When it comes to infrastructure, buyers of new condominiums may have less to worry about. “Walls and windows are better insulated now. Central hot water systems are more common, replacing individual hot water heaters in units,” says District architect Philip Esocoff, who has designed about 1,200 condo units in the city during the past decade.

Esocoff suggests that noise-sensitive buyers pay attention to the sound transmission class (STC) rating of walls and windows. “Generally, the higher the number, the better for blocking noise,” he says. An STC rating of 60 is a good for demising partitions between units, he notes, and windows facing heavily trafficked avenues should be rated at least 36.

But assurances of sound-absorptive construction may not turn out as promised. Urban designer Patricia Zingsheim bought her Massachusetts Avenue condo in 2004 before the building was finished, based on the spacious design of the 1,400-square-foot unit. Now Zingsheim says she is regularly awoken by the pounding sounds of runners on treadmills in the fitness center on the other side of her sleeping area.

“Before buying, I asked questions and was assured by the sales team that noise wouldn’t be a problem,” Zingsheim says. “But the acoustics are bad and would be extremely costly to fix.” Shared walls between units are fire-rated common elements that can’t be modified without the condominium association’s permission.

Zingsheim warns buyers against purchasing a new condo based on blueprints alone. “Cost-cutting may happen during the time between you sign the contract and what actually gets built, so you may not get the kind of construction quality you expected.”

A home inspection may not help pinpoint potential problems. “This process focuses on visible and accessible components of the individual unit, rather than the bones of the condo and the common areas,” Knull says.

According to standards set by the American Society of Home Inspectors, inspections of common areas in condominiums are not required as part of the condo unit purchase process. But buyers should be aware of the physical condition of shared elements that might impact their units — and wallets — in the future.

Loose mortar joints between bricks on building facades, flaking plaster in hallways and deteriorated roof flashing are all signs of trouble. “Make sure the funds for maintenance and repair of the building are sufficient to avoid a special assessment that will cost you a lot of money down the line,” Knull says.

Agent Rachel Valentino of Keller Williams Capital Properties suggests reviewing the condo documents, including disclosures or minutes from past association meetings about capital reserves for replacing or repairing common elements.

“There is a mandatory three-day rescission period in D.C. to allow buyers to review those documents before making a final commitment,” Valentino says. “That’s a good time to talk with the condo management or board committee members about any concerns.”

Deborah K. Dietsch is a freelance writer.