Andy Ennis is hoping that what MacDonald's has done for hamburgers and Century 21 for real estate, Mr. Build will be able to do for his home-remodeling business.

Ennis, president of AA Custom Building Enterprises of Manassas, is one of four contractors to have agreed to buy home-remodeling franchises from Mr. Build Inc. since the California company last month kicked off a selling campaign in northern Virginia and the District. The company next month plans to begin seeking suburban Maryland franchises.

"I expect Mr. Build to increase my business by providing advertising and name and reputation of a national remodeling company," Ennis said. "The size or bigness of the company probably is the major factor I see going for it."

The franchising firm hopes to sign up 50 local contractors by July 1, when the company plans an advertising blitz to introduce the new operation, said William H. Taylor, director of Mr. Build's mid-Atlantic region. By next year, the company hopes to sell 125 franchises in the Washington region, he said.

Currently, T and L Contracting Inc. of Fairfax, Guertin Associates of Herndon and Wenger Homes Inc. in Gainesville, Va. have signed on, Taylor said.

The latest attempt to franchise the home-improvement industry, Mr. Build was formed April 1981 by Art Bartlett, founder of the successful Century 21 franchise network. Mr. Build already has franchises operating in California and has established regional marketing subsidiaries in Texas, Chicago and elsewhere in the country.

Mr. Build was established to capitalize on the burgeoning home-remodeling industry, Taylor said, noting that the Commerce Depaartment estimates that $30 billion was spent on home improvements in 1981 and that $100 billion will be spent by 1988.

"People today with growing families are finding that they only owe $30,000 to $40,000 on their houses and rather than sell it and buy an expensive new one, it's cheaper for them to take a second deed of trust or a mortgage and spend the $10,000 to $30,000 to add bedrooms," he said.

Mr. Build franchises, through the parent firm, will offer customers financing plans for the remodeling and will provide them with a performance and completion bond covering the work, including that by subcontractors, Taylor said. He said Mr. Build also plans to buy building materials at discount rates for its franchises.

Taylor, based in McLean, promised top-quality work by Mr. Build franchises noting that the company is scrutinizing contractors and checking their trade and credit references. "We want someone with a proven track record or someone with a limited track record but with growth in mind," he said. "The key to a successful franchise is bringing in quality people."

He estimated that there are 3,500 home remodeling contractors working in Northern Virginia and the District.

Contractors accepted for Mr. Build franchises pay $6,900 for their franchise and $1,000 for bonding and a percentage of their revenue.

Ennis said Mr. Build's emphasis on quality work and the bonding were key factors that attracted him to the company. "They're interested in bringing integrity and quality to the remodeling business; that's why I got into this," he said. "I've thought that that was something the industry was lacking."

Ennis, who started his firm after retiring in November as a Marine Corps lieutenant colonel, learned carpentry as a boy from his father and remodeled several homes while in the service.

"A Mr. Build franchise definitely will give me an edge on the competition," he said, citing the planned regional advertising and building material discounts. "I don't know if this will put any of them out of business, but those on a fly-by-night basis will be hurt."

Allan L. Wenger, owner of Wenger Homes, is banking that Mr. Build's advertising will establish a good reputation for the company so that more customers will be attracted to his franchise. "If I don't get the extra work, then I've wasted the $8,000," he said.

"I think it is kind of a gamble, but it's not so much a spin of the roulette wheel," said Wenger, who has been in business for a year. "I think it's a good, solid idea. The timing of the idea is correct, and the need for it is out there."

Jack Guertin, president of Guertin Associates, says he hopes Mr. Build would double or triple his home-remodeling business.

Spokesmen for the National Association of Home Builders' National Home Improvement Council said previous attempts to franchise the remodeling industry have failed. Other companies also are trying to franchise the market now, they said.