Three Cheers for Lexington's ADU Ordinance


Lexington is in the midst of a mounting housing shortage. Happily for residents and aspiring Lexingtonians alike, the city’s planners are taking this potential affordability crisis seriously. While much of the conversation still centers around whether or not to expand the urban growth boundary, there are still plenty of opportunities to foster more housing construction in already built-out areas. Last year, for example, Lexington planners made it easier to add more housing in struggling retail hubs like Turfland and Hamburg.

Continuing this trend, Lexington planners announced a new Accessory Dwelling Unit (ADU) ordinance earlier this year. An ADU, also known as a “granny flat” or a “casita,” is a small extra housing unit that shares a lot with a larger single-family home. These can be attached—typically filling up a disused basement or attic—or detached—as in a disused garage or in a new structure altogether.

Given the low cost to add an ADU to a home, they provide an opportunity to add housing that’s inherently affordable to existing neighborhoods, without disrupting community character. This would go a long way toward keeping young professionals and downsizing seniors in Lexington. It would also help to address rising housing demand, as 40,000 more Lexingtonians are expected to arrive by 2025.

But let’s imagine that you’re not a renter or a new arrival: why should you care about ADUs? There are also substantial benefits to current homeowners in allowing ADUs. Many families will now be able to add an ADU to their property to supplement their income. Growing up, the family of a friend who lived in Mt. Vernon did exactly this. This extra income can be especially helpful for seniors, who may have too much space and not enough financial support, which is why the AARP has been a leader on legalizing ADUs.

Alternatively, ADUs can be used to support multigenerational living, with young adult children or aging parents enjoying an independent living space. My neighbors in Kenwick had an arrangement like this, converting the space above their detached garage into an extra apartment, and it worked well for them. All of this is to say, there are a lot of reasons to like ADUs.

So what exactly does the Lexington ordinance do? In most key respects, the current proposal is a model ADU ordinance, learning important lessons from cities that have already piloted ADUs. Let’s run through some of the key rules:

The Basics: The proposed ordinance would allow one ADU per lot, as-of-right, anywhere that low-density residential is allowed. That is to say, if a homeowner follows the rules, she can build an ADU without much added fuss. This keeps everything simple and transparent. As my Strong Towns colleague Daniel Herriges has argued, adding too many new rules or permits can act as roadblocks to new ADU construction, without creating any tangible benefits for neighbors. 

Bulk: Under the proposed rules, ADUs can be 800 square feet, maximum. If the ADU is attached (i.e., in a garage or attic), it’s capped by the same floor area rules that cap the size of all single-family homes. If the ADU is detached, or in a stand-alone structure, it can’t be more than half the size of the main home on the lot or 625 square feet, whichever is greater.  No ADU can be taller than the main home or 20 feet, again, whichever is greater. (If you can’t tell, planners love formulations like this!) The goal here is to keep ADUs small and inconspicuous.

Site Planning: Under the proposed rules, any detached ADU must sit behind the rear wall of the main home and three feet away from any lot line. The building footprint of an ADU, or the amount of lot area that it takes up, cannot be more than the primary home. There are no minimum lot size requirements for ADUs, which would have discriminated against more modest homes. If you’re familiar with Lexington building rules, you’ll notice that these rules are basically just a slightly more restrictive version of the rules that already apply to accessory garden sheds and workshops!

Owner-Occupancy Requirement: Owner-occupancy requirements force homeowners to prove that they live in the home where they want to add an ADU. This requirement can make it much harder to secure financing and can result in far fewer ADUs getting built. This is why many cities that pioneered ADUs have scrapped the owner-occupancy requirement. Lexington’s planners did their homework on this issue: the proposed rules do not place owner-occupancy requirements on ADUs. Homeowners only need to prove their residence if they intend to use the ADU for short-term rentals. 

Parking Requirements: ADU residents are far less likely than residents of single-family owners to own a car or drive. Yet many cities who pioneered ADUs tried to require that each unit come with additional off-street parking space. This was quickly revealed to be a mistake: parking requirements are expensive and make ADUs technically infeasible in neighborhoods with many small lots, as in much of Northern Lexington. Again, lesson learned: the proposed ordinance does not mandate additional off-street parking. As the Lexington planner Chris Taylor succinctly put it, “The ADU ordinance is intended to provide housing for people and not for cars.”

Design: With respect to design, the proposed rules are quite conservative: multiple front-facing doors aren’t allowed, and any exterior stairs must be along either the side or rear wall. As my friend Blake Hall—organizer of Build a Better Lexington—has pointed out, the front door rule could make some garage-to-ADU conversions difficult. I’m not thrilled about the rule either—it’s strictly aesthetic, serving no purpose other than to hide the ADU. But it speaks to the quality of the ordinance as proposed that this is the only real thing I can find to quibble with.

All in all, this is an extremely well-crafted ADU ordinance, incorporating many of the lessons learned from other cities. The proposed rules—combined with an associated Homeowner’s Guide, a collaborative project of the UK College of Design, AARP, and Lexington planners—would support the creation of a lot of new gentle infill housing, whichLexington urgently needs. It’s a great next step for a growing city.

(Top Photo Source: Britt Selvitelle at Wikimedia Commons)


Are you a Lexington urbanist who wants to get involved? Lexington planning staff are still soliciting public input. You can fill out this online survey until Friday, August 23rd at 5pm. Otherwise, the proposal will head to the Lexington Planning Commission in September and then to City Council after that; multiple public hearings will be held for each.  Follow Imagine Lexington on Twitter for additional updates.