When new construction began to dry up as the economy slid downhill, architects who usually concentrate on designing office buildings and houses began thinking smaller: bathrooms, basements, even closets. Most architects didn’t get into the field thinking they’d be using their expertise to remodel homes, but some of them have started turning to residential customers’ modest projects in order to survive. And this “Home Depot crowd,’’ as some architects call them, isn’t afraid to compare prices.

“Ordinarily I wouldn’t think of people shopping for an architect the way you’d shop for a microwave oven,’’ said de Sola.

Architects — especially those who design retail spaces, hotels, and office buildings — were hit hard when the economy tanked. Architecture firms have shed a quarter of their jobs since July 2008, according to the Bureau of Labor Statistics. Residential architects felt the pain early on, but their phones have been ringing lately as homeowners who are reluctant to move amid a shaky market look to improve their living spaces. In fact, home remodeling is projected to hit bottom this quarter and steadily increase throughout the year, according to a study by Havard University’s Joint Center for Housing Studies.

“The residential market is basically coming back,’’ said Kermit Baker, chief economist for the American Institute of Architects and project director of the Remodeling Futures Program at the Harvard center.

The home improvement sector is often overlooked by architects, who have to have at least five years of college and then complete an internship and pass a seven-part exam. With all this training, architects tend to go after work that is more lucrative than home renovation, which is often handled by designers and contractors.

But it’s a $250 billion-a-year industry, and while not as robust as it once was, it has surpassed spending on new home construction. And with interest rates low and demand high after many homeowners waited out 2009 hoping the economy would improve — 62 percent of homeowners plan to renovate this year, according to an American Express survey — more architects are opting in.

“You suddenly have architects out there who say, ‘Hey, I’m happy to do a residential remodeling project,’ ’’ Baker said.

Cambridge architect Frank Shirley recently talked to a South Shore family about adding a bedroom and bath and enlarging another bedroom in a house that is “stuffed to the gills,’’ he said. Shirley says he probably wouldn’t have seen such a relatively small project when the housing market was stronger and the family could have afforded to move into a bigger house.

Douglas Ruther, who has a one-man architecture firm in Brookline, is used to doing home renovations in the $250,000 to $500,000 range, with some topping out at more than $1 million; now he’s in the middle of four basement remodeling jobs priced at $50,000 to $75,000.

Some laid-off commercial architects have turned to residential design to survive the downturn, often doing small projects for people they know or happen to run into. About a month after Steven Vincent lost his job at ADD Inc. in Boston in February 2009, he was in his gym clothes, standing in line at the bank, when he struck up a conversation with a developer who wanted to build a structure to house his car collection. And with that, Vincent had his first client. Since then, he has helped a friend with a deck, done some drawings for another friend who was thinking of remodeling his condo, and worked on designs for a former co-worker who was building a house in Rhode Island.

“The residential for me has been kind of what got me through this,’’ said Vincent, but he didn’t get enough of it to make ends meet. He had to tap into his savings to support his family, and he recently took a job with Symmes Maini & McKee Associates in Cambridge, doing commercial work.

As project sizes have gone down and budget sensitivity has gone up, residential architects are also finding they have to take on increasingly detailed duties to make a living — doing the drawings themselves instead of hiring a draftsman, overseeing construction work on-site to save time, and consulting for a few hours on things as small as paint color. De Sola, the Cambridge architect, has even turned into a contractor of sorts, finding electricians, plumbers, and carpenters to bring his designs to life instead of having his clients hire a separate contractor to do the same thing.

Working with residential clients is a more personal process than designing an office building, architects say, and while helping people bring their dreams to life can be gratifying, it can also take a lot of hand-holding to turn those dreams into reality.

“I avoided residential like the plague,’’ said Thomas Downer, who did commercial work for 13 years before opening a one-man home design firm in Cambridge. Now such jobs are his bread and butter.

Some architects enjoy the personal touches involved in working with homeowners, while others can’t wait to get back to bigger projects. But for now, said Cambridge architect Shirley, many of them are sweating the small stuff: “There’s a lot of aggressive pursuit of work over what many people would consider very modest work.’’

Katie Johnston Chase can be reached at johnstonchase@globe.com.