Small-Scale Residential Housing: Infill Housing, ADUs and Tiny Homes

Joe Archibald

 

Often when people think about sustainable building, they think about material sourcing, location of the building on the property, renewable energy sources and the other more common metrics.

Just as important a factor, however, is where the building is located within the community.

When it comes to housing, especially here in the mountains around Asheville, finding suitable building lots is getting harder.

Many builders and clients have realized that building smaller, utilizing infill lots and developing within existing neighborhoods is a great way to not only weave into that community, but to also reduce the need for car trips, lessen the creep of suburban sprawl and bring more vitality to areas that have been previously neglected.

Also, as more people live alone, remain single longer or choose to not have children, smaller-scale housing is becoming a more popular option.

Let’s take a quick look at some recent initiatives that the City of Asheville has worked on in an effort to promote small-scale residential development to create a denser and more vibrant urban core.

Infill housing

Infill housing, in its simplest terms, is filling in the gaps between existing buildings.

In city planning terms, it refers to the rededication of open land to new construction, typically within urban areas. Sometimes these open spaces were previously built upon but have gone vacant over time. More commonly new buildable areas are created through the reallocation of property boundaries, such as when an owner decides to subdivide their property to create two or more parcels where there was previously only one.

Many of Asheville’s suburban developments of the early 1900s had lots that were in excess of an acre in size and, over time, as the city has grown outward, these developments are no longer suburban but are now considered a part of the urban environment. (Think about Kenilworth and Lake Shore Park as examples).

In an effort to create more available land for housing development the City of Asheville’s Urban Planning Department in 2017 passed new zoning regulations to the Unified Development Ordinance (UDO) that allow for reduced lot parcel sizes when an owner decides to subdivide their property.

Allowable lot widths were decreased, along with reductions to overall lot square footage. Depending on where the existing building is located on the lot, these reductions may be even more. Off-street parking requirements still remain, however there are some adjustments, again depending on the existing lot conditions.

ADUs

Accessory Dwelling Units, or ADUs, are housing units that are either part of the main residence on the property (known as attached units, basement or attic apartments) or a separate building that is smaller in size and scale to the main building (known as detached units).

Detached units are the type often associated with ADUs; garage apartments or granny flats are typical names for these units. All ADUs are required to have a separate electrical service meter, and detached units often require separate water and sewer connections.

These last two items can make ADUs less affordable to build than clients desire. Even with their limited size (800 square feet is the current maximum), they truly are another house with regards to their construction and utilities required.

In an effort to promote this type of development, Asheville’s Urban Planing Department passed new regulations governing the size and location on both attached and detached ADUs.

“To address the lack of housing, in 2015 we decided to update standards for ADUs to make them easier to build and to allow for more housing to be distributed throughout the city in backyards,” said Vadilla Satvika, an urban planner with the City of Asheville, regarding the new regulations that were approved in 2016. “We realized … that a key challenge to allowing them was that current standards (at the time) only allowed ADUs on conforming lots. … Effectively 20 percent of properties were prohibited from ADUs just because their lot was not meeting standards, maybe having the lot frontage too narrow or a garage that could be converted to an ADU was encroaching into a setback. So we moved ADUs from the UDO article that requires lots to be conforming and into another place. Now, all residential parcels can build ADUs.”

This change has led to an increase in the number of ADUs being built, however there remain challenges in the process which have slowed progress toward the city’s initial estimates of the number of units that would be created.

The biggest of these challenges is cost; an owner either needs to have cash in hand or the ability to obtain a home-improvement or other loan on the existing building in order to have the funds to construct the ADU. Bankers report it is quite difficult to obtain a mortgage directly on a detached ADU, which hinders the ability for many to construct them, even if they have the space and desire.

Tiny homes

Another potential option for increased housing options and density within existing residential areas can be found in tiny homes.

Generally considered to be dwelling units of less than 300 square feet, most tiny homes are bile. Most, however, are never moved, despite being installed on temporary foundations.

While there are a few tiny home communities that have developed in the greater Asheville area in recent years, they have not become a significant component of small-scale residential infill development.

Challenges to their increased prevalence include cost and the availability of utility connections, along with regulations restricting the use of trailers (recreational camper trailers) as long-term housing. (Currently, the use of RV trailers parked for housing in a city residential area is not allowed for long-term use. While tiny homes aren’t typically considered an RV trailer, that is the closest similar structure type.)

The City of Asheville has not created any significant regulations directly pertaining to tiny homes to date, nor have state or national building codes. There are discussions regarding tiny homes within many building code development committees, and there might be specific building codes adopted in the coming years.

Societal challenges

As with any new development, infill housing, ADUs and tiny homes have their detractors.

Despite the generic opposition to increased density, the primary argument against these forms of small-scale residential housing relates to the lack or age of public utility infrastructure. These concerns typically revolve around water and sewer line capacity.

While it is a fact that some areas of the city have infrastructure issues and that replacement of existing utilities is much more difficult than building new infrastructure in a suburban area, it is also true that developing new housing within existing neighborhoods and urban cores has a far lower life-cycle impact than any ‘green’ suburban development.

Another infrastructure issue is stormwater capacity. Properly designed and built infill development should not contribute negatively to stormwater impacts, especially when compared to the impact of new highways or large scale suburban retail development, something that more dense urban neighborhoods offer as contrast.

The takeaway

If you are a green builder, developer or client who is looking for a new avenue to reduce the impact on the land in our community, give some thought to creating small-scale housing options.

Not only are they a current growing trend, they truly are one of the best sustainable housing options that can be made.

 

Joe is the owner of Narwhal Design|Build, PLLC, a craft-based design and fabrication firm specializing in small-scale residential and renovation design work and custom woodworking. He is a licensed architect in North Carolina, Maryland and Washington D.C., who serves on the City of Asheville’s Planning and Zoning Commission. He lives above friends in a 1900s duplex in a moderately dense North Asheville neighborhood. Connect with Joe at narwhalbuilt.com. 

You can also view this article as it was originally published on pages 62-63 in the 2019-2020 edition of the directory.