Bill Zoslocki fondly recalls the basic homes his father and uncles built in Modesto back in the '40s, '50s and '60s.

The floor plans -- often with two bedrooms, one bathroom, a one-car garage and less than 1,000 square feet -- were designed on kitchen tables and named after family members, like Florence, Wylma and Cheryl.

By the '70s when Zoslocki became a building contractor, his homes provided three bedrooms, 1½ baths, two-car garages and 1,300 to 1,800 square feet.

"That was a big house, that 1,800-foot model," said Zoslocki, president of the Building Industry Association of Central California.

Such homes aren't considered big anymore.

Stanislaus County is following the nationwide trend of supersized homes. The average new house in the county now tops 2,200 square feet.

New houses today routinely pack two-stories with four or more bedrooms, three or more baths and garages for three cars.

"In the last 30 years, family size has declined more than 20 percent, but home sizes are up by more than 50 percent," said Gopal Ahluwalia, vice president for research for the National Association of Home Builders.

"People do not buy homes just to meet functional space needs," Ahluwalia explained. "They do it for their lifestyle."

In the minds of buyers, bigger seems to be better.

"We're meeting market demand. People like the extra bedroom, the extra bathroom and the big great rooms," said Keith Schneider, development coordinator for Diablo Grande where new homes are 3,200 to 3,800 square feet.

"The home has become the center of people's social life," Schneider said. "These homes give them the room they want to entertain."

And they give builders the profits they need to cover soaring land and construction costs, Ahluwalia noted.

"When land prices go up, the house sizes go up" to justify the expense, Ahluwalia said.

Most homes nationwide now have two stories because second-floor construction costs are less per square foot, Ahluwalia said. The cost of land and kitchens -- typically a home's most expensive room

-- remain the same no matter how many bedrooms are added upstairs.

"In Orange County, we're seeing 5,000-square-foot homes on 5,000-square-foot lots," Ahluwalia said.

Such monster homes aren't the norm for subdivisions in the Northern San Joaquin Valley -- yet.

"I'm sure a builder will test that market, and we'll see if it works," Schneider said.

Testing markets is down to a science for today's builders, which is far different than the casual way Zoslocki's relatives used to draw house plans.

Studies target buyers, profit goals

Before builders buy land now, Zoslocki said, they do a feasibility study to determine development costs, then a marketing study to figure out what types of homes must be sold to cover those costs.

Zoslocki said he knows smaller homes would sell quickly in the valley, but builders wouldn't be able to earn enough profit to make them feasible.

"The larger the house you build, the less it costs (per square foot) to build," said Zoslocki, noting how buyers more willingly pay higher prices for larger homes. "That's why you see the big boxes being built. That's what the market wants, or they wouldn't be selling."

New home sales are brisk in the valley, according to statistics gathered by the Meyers Group consulting firm.

Meyers tracks new home sales in Stanislaus, San Joaquin and Merced counties, as well as in select regions nationwide.

It uses that data to advise developers on what to build, where to build and the buyer they're likely building them for, according to Stephen Smiley, a Meyers Group principal based in Pleasanton.

Meyers' data shows that in Stanislaus County the first three months of this year, 58 subdivisions sold 947 homes that averaged 2,266 square feet and $303,516 each. Meanwhile, in San Joaquin County, 96 subdivisions sold 1,612 homes that averaged 2,325 square feet and $365,065.

In 27 Merced County subdivisions, 535 homes were sold. They averaged 1,837 square feet and $247,297.

Smiley said Bay Area commuters are driving the valley's new home market and pushing up home sizes.

"They can go out to the valley and buy a bigger house for less money than they can in the Bay Area," Smiley said.

In a new Tracy subdivision, for example, 4,000-square-foot tract homes on large lots are selling for $700,000, which Smiley said Bay Area residents consider reasonable.

Most valley residents, however, can't afford anything near that expensive or that big. Smiley said that's why several developers are considering ways to lower construction costs by shrinking lot sizes.

"You're going to start seeing smaller lots, and the houses are going to stay about 2,200 square feet," Smiley predicted.

The average new home lot in the valley is about 6,000 square feet, Smiley said, but new developments are considering building on lots as small as 3,500 square feet.

By comparison, national lot sizes for new homes are about 9,000 square feet, according to Ahluwalia.

Bee staff writer J.N. Sbranti can be reached at (209) 578-2196 or jnsbranti@modbee.com.