Design a Basement Apartment

Whether you're looking for extra income or need a place for aging parents to live, here are tips for flipping your basement into a comfortable living, dining and sleeping space.


By: Barbara Ballinger

Homeowners have numerous reasons to convert a basement into an apartment: A returning college grad might need a rent-free place to live while accumulating savings; they may need a place to house an au pair for their young children, have an aging parent or grandparent who doesn't want to live alone, or want income by renting otherwise unused space.

"If the home is near a college, there could be high demand for a renter who doesn't want to live in a dorm," says Neil Salvage, general manager of Lending Tree Home Pros, which connects contractors and homeowners.



Kathryn and Steven Van Asselt found yet another reason after they purchased a house in Portland, OR, two years ago with a 700-square-foot basement. They knew the location would appeal to those moving into the area and not wanting to reside temporarily in a hotel.

With Steven's expertise as a general contractor and owner of Van Asselt Construction, they also knew they could make improvements affordably, and their prior experience as landlords gave them a leg-up on what renters seek and how the process works. They first checked city regulations to be sure they could have someone live fulltime within their premises and pay rent, install a working kitchen, meet criteria for minimum ceiling height (at least 6'8"), and have the right number of egresses for safe exit.


To save space in their basement apartment Kathryn and Steven placed the washer and dryer in the bathroom.

To save space in their basement apartment Kathryn and Steven placed the washer and dryer in the bathroom.

Next, they had the space inspected to be certain it was dry—and would remain so. Then, they were ready to make changes—provide a private access to the street so their tenants wouldn't have to enter and exit their home, break through concrete walls to enlarge windows to add light to the bedroom and living walls, add insulation for warmth and sound dampening to cut noise to their upstairs level, install a full kitchen and bathroom, and paint walls.

Furnishing the apartment became the fun part of the process, but they kept costs down by purchasing mostly at IKEA. "We knew that people like IKEA because it's modern and cheerful," says Kathryn, a professor at Portland State University. She also knew to add in nice perks—good coffee maker, HD flat-screen TV, towels, real closet space, laundry equipment, and stack of maps and brochures about Portland. They estimate total costs at between $15,000 and $20,000, and have been able to find renters through Craigslist who pay $400 a week, with one-month minimum stay.

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Here's what else the couple and others suggest:

  • For smaller apartments, focus on space-saving furnishings and appliances, such as wall-mounted toilets and Murphy beds, says Marianne Cusato, author of The Just Right Home and designer of the tiny post-Hurricane Katrina cottage.
  • Tie plumbing into the main home's existing stacks to save since this is typically the biggest basement expense, says architect Duo Dickinson.
  • Focus on comfort and warmth. Go with carpet tiles or area rugs atop cold stone or concrete; insulate walls, ceilings, floors, and pipes, and use materials that won’t decay if wet, says architect Joe Eisen.
  • Consider a separate mechanical system and sound-proof it if located next to the apartment.
  • Install sufficient artificial light since natural light may be minimal; this may require upgrading your home’s electrical panel.
  • Exposing ceiling beams and ductwork can look fine, says Bree Al- Rashid, managing broker at Redfin Corp; some actually prefer it to dated looking acoustical tiles.
  • If older relatives come to stay now or down the road, consider installing an elevator or at least having a space reserved for it. Though it can run $25,000, that's far less than an assisted care facility, says architect Aaron D. Murphy of ADM-Architecture and a Certified Aging in Place specialist for the National Association of Home Builders. Consider other universal design ideas: color contrasts when levels change, zero thresholds for showers, grab bars in tubs and by toilets, wider doorways, lower counters for wheelchairs to access easily, he says.
  • Think furnishings and surfaces that are easy to clean and maintain, so they'll wear well and look good after renting repeatedly.

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