Ubiquitous in the early 20th century, the caretaker’s cottage, carriage house, and attic apartment were zoned out of existence with the mid-century move toward single-family districts. This traditional typology, now called an accessory dwelling unit (ADU), is gaining popularity once again. Planners, newly aware of their benefits to communities, are now encouraging the creation of ADUs. These might take the form of a small apartment located in the attic, basement or wing of a single-family home; above a garage or studio; or in a tiny backyard cottage.

Accessory dwelling units provide a discreet way to enrich the fabric of neighborhoods, mixing young with old and affluent with service workers. Without changing the character of a neighborhood, they can help to increase density to the levels needed to support a community’s desired services and amenities. Increased density brings with it increases to the tax base, with little or no additional infrastructure expenditure.

ADUs can provide homeowners supplemental income, security and, when desirable, maintenance assistance and companionship. The ability to generate income from an ADU may enable prospective homeowners to qualify for a mortgage, families hard hit by the recession to avoid foreclosure, and retirees to continue to afford taxes and other homeownership expenses.  Those who often travel or hold multiple residences find comfort in knowing that a renter is keeping a watchful eye on their property. At the same time, these small housing units provide an affordable housing option for recent graduates and young couples who are finding it hard to get on their feet in this tough economy.

Providing housing for aging boomers may be the greatest argument of all.  According to 2012 census projections, the 65 and older population is expected to more than double by 2060.  80% of baby boomers would prefer to stay in their home or community when they age. An ADU tenant could provide care to aging homeowners and their property in return for housing. When the primary residence feels too large, seniors could rent the large house and moving into a smaller, accessible ADU, continuing to age on the same property they have occupied for a lifetime.

The ability to create ADUs in historic districts is critical. The income they generate could be the key to making the acquisition and restoration of a historic property possible. In some cases, projects involving the creation of an ADU in a historic structure qualify for federal or state historic preservation tax credits.

In all situations, ADU’s should be created with sensitivity to the nature of the primary residence and neighborhood. When the unit is incorporated in to the primary residence, its entrance should be discreet. The conversion of alley garages, barns and other outbuildings should strive to maintain the character of the original use and not upstage the house. New, free-standing ADUs should be diminutive and inconspicuous.

The two following examples demonstrate how an accessory housing unit can be incorporated into an existing home. In one case, the prime objective is economy, in the other it is aesthetics.


Carriage House, Durham CT (© Bazazi Design )

I accommodated the client’s need for an in-law apartment and 3-car garage in a new ‘L’ off of an existing home that references the carriage house typology. The tower, which links the new structure to the existing, houses a stair and small residential elevator. (rendering above)


In-Law Apartment, Middletown, CT

These clients came to me with a very limited budget and a sketch of a 744 sq. ft. in-law apartment addition that they couldn’t quite resolve. By removing one partition in the existing house and completely rethinking the addition, my design solution graciously met all of their needs in 30% less area, representing a $35,000 construction savings. Rather than overwhelm the existing house, it complimented it.  An accessible, covered, secondary front entry, replaced the full flight of stairs in the rear that they had envisioned.