Ready to make the most of your home's extra spaces? If you have an unused attic or basement, you likely have lots of untapped potential for living space.

Real estate and home remodeling expert Marina Vaamonde, owner and founder of HouseCashin, America's biggest marketplace for off-market houses for sale, says converting a basement or attic into a bedroom makes financial sense.

"It absolutely adds value to your home and allows you to raise the rent of your property," she says. "Depending on where you live, it could allow you to increase your rent by $100-$250 per month."

According to the National Association of Realtors' Remodeling Impact Survey, homeowners who converted their basement into a living area spent an estimated $46,900 and recovered $30,000, resulting in 64% of value recovered. The same survey found converting an attic into a living area cost $80,000, with $45,000 recovered from the project, resulting in 56% of value recovered.

The return on investment is solid, and so is the expanded use of your living space. Still, there are many factors to consider before you commit to a conversion project.

*Requirements

Sarah Barnard, a designer of personalized, sustainable spaces who is WELL- and LEED-credentialed, advises checking with your city before starting the project. Local fire codes may regulate projects based on the attic or basement's ceiling height, amount of floor space, number of windows, suitable access in and out of the space, and more.

"Different cities will have unique requirements for turning nonhabitable spaces into habitable rooms," she says, noting it's important to understand how you wish the space to function in the future so that you can discuss options with the city to best determine a plan of action during the initial planning stages.

*Remodeler Beware

Assess your space, especially a basement, to make sure it's suitable for a conversion.

Vaamonde says the biggest factors to consider are humidity, mold and water. She says many American homes are at a greater risk for basement humidity and mold because most aren't waterproofed. Plus, older homes were built when homebuilding standards were lower.

"If left untreated for too long, mold can be a very serious health hazard, made even worse if you have someone living in the basement," says Vaamonde, encouraging homeowners to install a dehumidifier and insulation, and verify that there's no mold.

Another thing to consider: you'll need to extend your HVAC system to the basement and/or to heat and cool the area.

*Basement Versus Attic

Consider which space will work best for your new bedroom: the basement or the attic.

Cristina Miguelez, a remodeling specialist at Fixr, a home remodeling information website, says the basement is generally easier and less expensive to convert into a bedroom.

For a basement, she advises waterproofing and insulating the whole basement and creating finished surfaces. Next, add an egress -- a window or door from which you can exit the basement directly to the outdoors. Consider adding a closet, which may or may not be a code requirement. A closet does add resale value.

Adding a basement bathroom isn't too big of an expense since plumbing is often already located in the basement. Still, toilets can be an issue.

"Most toilets are gravity fed, while your basement is already underground," says Miguelez. "That means that you will likely need a pressure-assisted toilet to help pump everything up and out. These can be noisy -- think the sound of a plane taking off -- so some people like to locate the bathroom as far from the sleeping area as possible."

When choosing to turn the attic into a bedroom, remember that attics can get very hot, which means you'll likely need extra insulation as well as separate ventilation to help protect your roof.

Attics need an egress, too, and you'll have to finish the walls and floor. Keep in mind that attic ceilings can be tricky, often leaving the space with little head room.

"You can only declare the square footage as living area if it reaches 7 feet or more in height," says Miguelez, noting sloped walls don't count toward total square footage. "And a bedroom needs a minimum of 70 square feet to pass code."

Attic bathroom configurations can be even trickier. She says you'll need standing room, as well as 30 inches for the toilet to sit in by itself and 20 inches for the sink to sit in by itself. Next, the shower needs a minimum of 30 square inches with at least 7 feet in height.

*Project Management

Don't forget to add lots of lighting, since basements and attics are often dark. And while many household projects are easy to tackle, Vaamonde cautions against doing the work yourself.

"This is not a DIY project," she says. "Please hire expert contractors to do this project for you."