The glory days of flipping houses had everybody and their mother’s brother thinking they were going to become real estate millionaires overnight. But the credit crunch and continued housing market woes have stopped many aspiring real estate investors in their tracks.

But you may not have to give up the goal of profiting from real estate. If you have an unused garage or empty outbuilding on your property, turning it into a rental could be one way to bring in extra income. Just make sure you plan your project carefully, don’t cut corners and check local zoning laws.

Bring in the garage conversion pros

Involving professionals in a garage conversion can help homeowners avoid major problems down the line. Although the DIY route is tempting, hire an architect or designer to help plan the garage conversion project. “It is much more complicated than the average person thinks, and the city will require a set of plans signed and sealed,” says John Hock, president of John Hock Enterprises, a general contracting firm in Delray Beach, Fla.

Hiring a licensed and trained contractor, plumber and electrician can also prevent serious mistakes. “I’ve been in the business all my life and I wouldn’t do my own wiring or my own plumbing,” says Bob Boothroyd, construction manager for the Boothroyd Group in Greenwich, Conn. “If a homeowner should have a fire or plumbing leak, the insurance company will look to see who did the work. If they find out that an owner did it or had an unlicensed friend do it there’s a big chance they won’t pay the claim.”

Using a licensed plumber is also important if your home has a septic system. Your county or state may require you to upgrade to a larger system if you add bedrooms, since your change indicates that additional people will probably be living there.

Boothroyd suggests that homeowners look for reputable contractors that belong to organizations such as the National Association of the Remodeling Industry.

Check local zoning laws

Zoning laws vary by municipality, but in many places building permits will be required for a garage conversion. Without appropriate permits, your local government could halt construction. “The homeowner will need to prove at their expense the building thus far is up to code and provide a set of plans and building permit to continue,” says Hock.

In some cases, converting a garage into a rental unit turns the property into a two-family home. If a kitchen with an oven is installed, for instance, the property often is considered two-family. In some communities, however, installing a kitchenette without an oven may mean a property keeps its single-family status. “A lot of towns allow family members to have a separate unit, some with cooking facilities, some without — a so-called in-law apartment,” says Boothroyd.

Your town also may require minimum room sizes for a garage conversion. Depending upon the size of your garage you may only be able to put in a studio apartment. Other garages, or buildings not attached to your home, may be suitable for a two- or three-room apartment.

Don’t be cheap

While you may be hoping to get away with spending as little money as possible to create your rental unit, $25,000 to $40,000 is probably realistic, says Boothroyd. “It’s not going to be $10,000 or $20,000, but if you’re going up to $50,000 or $60,000 you’re getting pretty fancy.”

Your ultimate budget will depend upon such things as whether your garage has access to existing utilities, such as air conditioning, as well as what part of the country you live in. You also may be able to cut costs by doing some of your own carpentry work or other tasks. But it’s best to err on the side of caution when assigning yourself work.

“You need to have a realistic assessment of your skills because frankly, you’re really building a little house except that you have the shell constructed,” Boothroyd says. “But you’re really doing the hard part. The finishing part is generally a higher skill level than a lot of the rough work.”