One of the things Chelsea Lipham cherished about her home in Portland, Maine, was how beautiful its tree-filled lot was. What she didn’t care for, however, was the cramped interior of her 100-year-old duplex. “I was feeling kind of claustrophobic,” says Chelsea, who is a registered architect. She imagined an open, airy space with better views of the canopy around her—something that was more like the cabin in the woods she grew up in.

After the city passed regulations that made it easier to build ADUs, Chelsea jumped at the chance to create her dream space. She envisioned a place that she, her husband, and son could move into and possibly rent out in the future. Thanks to smart product and material sourcing, plus the sweat equity she and her family put into constructing the project on nights and weekends, the 950-square-foot, two-story ADU came to just under $206,000. “It was all an experiment,” Chelsea says of the design.

When Chelsea started conceiving of the ADU, she focused on ways to maximize living space within the footprint she was allowed to have under Portland’s ADU rules, which led to a two-story design. She didn’t expect to build the ADU herself, but the prices contractors quoted were too high for her budget. Nearly half of it did go to experts for the foundation and sitework, plumbing, and extending the sewer and water lines to the back of the property—work Chelsea wasn’t able to do on her own. But because she had experience helping her father, who is a woodworker, build homes over summers when she was growing up, Chelsea “wasn't scared of needing to do most of the work myself,” she says. In a full circle moment, she began to teach her son how to chip in. “He had his little wrench out helping us do things,” she says.

Keeping the volume, layout, and detailing straightforward helped make the house easy to build. “I was trying to simplify everything as much as possible, but still keep things interesting,” she says. The ground level features a short entry hall that passes a workshop and office nook before opening to a double-height living room and adjacent kitchen and dining area.

$4,280 Permit & Impact Fees	$7,923.08 Appliances	$2,356.98 Cabinets/Counters
$12,375 Drywall	$22,079.99 Electrical/Lighting	$8,230 Sprinklers
$4,646.12 Flooring/Stairs	$37,150 Foundation/Site Work	$9,252.59 HVAC
$7,726.31 Insulation	$17,818.60 Framing	$3,643.20 Roofing
$5,368 Interior Finishes	$9,157.45 Siding	$19,408.77 Plumbing
$18,222 Windows/Doors/Hardware	$15,775 Water Line (from street)
Grand Total: $205,413.09

Upstairs, there’s a bedroom for her son, a bathroom, and a sleeping loft for her and her husband. Instead of enclosing her bedroom, which overlooks the living room, she chose to keep the wall framing exposed—which also adds visual interest—and pulls a curtain across it when she wants privacy. This way, the room feels more open and airy, plus she has more views outside through the living room windows and skylights. “It kind of feels like you're in a tree house,” Chelsea says.

Prioritizing energy efficiency also helped Chelsea rein in costs up front and longer-term. She designed a well-insulated envelope, using Rockwool insulation in the walls, ceiling, and roof. She also installed reclaimed foam insulation outside of the sheathing on the walls and around the roof structure, what’s known as “continuous insulation”: a continuous layer that minimizes thermal bridges. Then this was covered with another layer of sheathing and finally, the roofing. “This allowed us to have one heat pump for the whole house and it stays really nice and cozy all year,” Chelsea says.

The material palette comprises affordable materials and finishes—a polished concrete floor, drywall with a few plywood accents—as well as ready-made products, like an Ikea kitchen and DIY staircase kit from Fast Stairs. For the exterior, she splurged on solid pine and finished it in pine tar, a durable and affordable natural wood preservative that protects against rot, insects, and UV rays. It’s commonly used in Scandinavia on houses and boats. The pitch-black facade is durable and practical but also gives the house gravitas and nods to the surrounding pine trees that were so inspiring to Chelsea.

“First and foremost, I designed it for myself,” she says. “There is a distinct feeling that maybe you are no longer in a city but rather situated in a small cabin in the woods.”

More Budget Breakdown stories:

Here’s What It Cost to Build Two ADUs on the Same Bay Area Block

To Fill an ADU With Light, $55K Yellow Window Frames Were a Design Necessity

Project Credits:

Architect of Record: Studio Clad / @studio_clad

Builder/General Contractor: Studio Clad

Structural Engineer: L&L Structural Engineering