Although lots come in all kinds of shapes and sizes, from my experience, almost all single family home lots can put an ADU on it to varying degrees of sizes, costs, and creativity. However, certain lots definitely work better than others.
This is not a hard and fast rule, in general I like lots that are at least 6,000 sq ft and at least 1,200 sq ft of backyard space. This usually gives the most flexibility without having to resort to too many custom designs or setback issues.
Alley Access Lots
Not super common, but they are out there. I like these lots because the alley provides separate direct access to the ADU from the back of the property. This creates added privacy as you can orientate all your designs to the back of the lot. Parking can be located off the alley, adjacent to the ADU, or in the side yard set back area. Depending on the city, you might be able to utilize part of the alley’s width as your rear setback. You can also put up a fence for even more privacy between the main house and the ADU.
Corner Lots
Similar to alley access lots, I like corner lots because they are easy to separate out the access. I will add it’s easier when the front of the house faces the narrow side of the lot, which allows you to easily create a separate entrance to the ADU with a curb cut with a driveway. You might also be able to pull utilities easier to the side street instead of having to go the entire length of the lot.
Infill Lots
This is the most common kind, a lot with neighbors on three sides. The existing driveway can be used for access to the ADU, whether it’s a garage conversion or new detached ground-up construction. I would try to have the driveway be at least 20’ in width for cars to get in and out without interference. When that is not feasible you can park in tandem or create a parking spaces in the 10’ space between the ADU and the main house or the side setback space of the ADU.
Multifamily
Multifamily lots typically do not have enough extra land as they have denser build outs or are used for parking. Although you can convert garages, carports, laundry or storage rooms you are taking away important amenities for your renters. You will need to factor in higher vacancy rates as you try to find tenants that don’t care or adjust your rent accordingly. When they do though, it can provide handsome returns if you can fully take advantage of the two extra detached units plus one more from 25% of the existing structure.
