By definition, an ADU (short for accessory dwelling unit) is a second complete dwelling unit built on a lot zoned for single family residences. This special zoning category was created about a dozen years ago as way to allow seniors to live near their adult children rather than moving to senior facilities. It is believed — and experience seems to bear this out — that seniors who reside near the kids in ADUs rather than in assisted living settings live longer, healthier and happier lives.
Today, according to the very credible New York Times, nearly 20% of American families live multi-generationally (the statistic describes adult homeowners living with other adult members of their family). Hence the ADU boom.
ADUs are now allowed in many/most communities. Any unit with a second full kitchen is considered an ADU, and in most communities an ADU can be attached or detached from the main residence on that lot.
Communities limit the size of ADUs, typically between 500 and 1000 square feet. They also impose other restrictions, which I research before I begin planning with my clients.
I believe that ADUs should reflect the architecture of the primary home whose site it shares, and to some degree the architecture of the neighborhood, if the setting is suburban or urban.
The ADUs shown here are good examples. Each was designed at the same time as the main structure, but that is not necessary. The Lindal building system is flexible enough to morph into almost any architype.
In the first case, above, the larger of that two is a traditional unit, 999 square feet in size and sited less than 100 feet from the 3700 square foot primary unit. Like the larger unit, it has a steep roof pitch with shed dormers and is clad on the ground floor with horizontal beveled siding and on the top floor with shingle siding.
In the second case, above, a 500 square foot ADU is fashioned after the modern primary dwelling. Sited barely 50 feet from the larger home, the ADU was designed and sited so that the inhabitants of each dwelling will not be able to see into the other except for knowing that the “lights are on.”
Being built on a fairly wild site the area between the two units was planned to be a shared communal area between the two, a spot for outdoor dining and relaxing.
So... .what’s this!? TWO ADUs on one site!? Actually not: only one of the these two Lindal cabins (only 275 square feet each), built in the Berkshires in Massachusetts is an ADU. The other is an outbuilding. Which raises the subject of our next posting, “When is an ADU not an ADU?”
A caution about cost:
Many people think that a small cottage or an ADU is a low cost idea… that a 1000 SF ADU costs one-third of a 3000 SF house. As with German cars, couture, even Cheerios, that is not the case. A small house has proportionately more of the same cost centers — a fully equipped kitchen, a heating system, two bathrooms — than larger home and proportionately less “empty space.” Experience shows that a 1000 square foot ADU can cost $50 to $75 per square foot more than a 2500-3500 square foot home built on the same site.