By Dylan Bertet, owner of Build Better Properties (CSLB #1077286), a Bay Area design-build contractor.
An addition, an ADU and a second story solve different problems. An addition makes your main house bigger. An ADU gives someone else a separate place to live. A second story adds the most space without touching your yard.
Choose an addition if your house feels too small
An addition expands the home you live in: a bigger kitchen or dining room, more bedrooms and bathrooms. If the house itself is the problem, an ADU in the backyard won’t fix it. Additions also tend to add more value than ADUs because they add square footage to the primary home.
Choose an ADU for privacy or rental income
An ADU is a separate home with its own kitchen, bathroom and entrance, either detached in the backyard or attached to the house. It’s the right call for rental income, or for family who live with you and want their own space.
Choose a second story when you need a lot of space
A second story is the biggest option: the roof comes off and a new floor goes on top. It usually makes sense when you need about 1,000 sq ft or more and your lot is tight, or you don’t want to give up the backyard. It isn’t necessarily the most expensive choice, but it is the most involved. The foundation almost always needs reinforcing, as on our Fremont second story, where we installed 15-foot drilled piers, and it’s harder to do one without the project being treated as new construction.
What about tearing down?
A teardown only makes sense if you want a brand-new house for your own reasons, or if fixing the existing house would cost more than building new. For a home in good shape that needs 400 to 800 sq ft, an addition usually wins.
Planning an addition? Read our full Home Additions FAQ, see the cities we serve, or call (650) 801-2699 to have us walk your house.