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LOWERING THE COSTS OF BUILDING AN ADU THROUGH MODULAR CONSTRUCTION

TAMI SALVADOR CAMAS

HACK-A-HOUSE 2024

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SINGLE-FAMILY HOME DENSIFICATION

THE PROBLEM: The United States has a shortage of affordable housing.

75% of land is zoned for single family homes in the US. Most cities and states have not changed their zoning laws. It can be really expensive to remodel or add an ADU.

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SINGLE-FAMILY HOME DENSIFICATION

THE SOLUTION: Infill development to densify single-family homes by adding prefabricated ADUs.

CONSIDERATIONS: Jurisdictions nationwide are moving to allow more units of housing per parcel of land.

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HOW IT WORKS

Modular construction is a process in which a building is prefabricated off-site in about half the time compared to on-site construction, reducing labor and material costs. It has shorter development timelines and an overall safer and more efficient development process than manufactured homes.

Source: Building Affordability by Building Affordably

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COST COMPARISON

Buying a prefabricated unit is much cheaper than building the unit on site.

According to FIXR, the average costs of building a modular unit versus a stick-built unit (or built on site) are the following:

Source: FIXR

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DETACHED ACCESSORY DWELLING UNITS POLICY IN UTAH

Utah’s ADU Legislation varies by county or municipality.
Salt Lake City, Millcreek, Centerville, and Lehi have policies that allow detached ADUs, among other municipalities.

The Salt Lake County established that “Detached ADUs are also permitted but may only be built on single family home lots with an area of seven thousand square feet or greater.”

In 2023, the maximum size of an ADU increased from 650 sq ft to 1000 sq ft.
Under the previous regulations in Salt Lake County, detached ADU's were restricted in height to not exceed that of the primary residence.
The permitting and approval process of building ADU’s changed from an 9 months to 3 months

Source : Salt Lake County Ordinance

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IMPLEMENTATION

Salt Lake County Other municipalities in Utah Other States that allow detached ADUs

US states such as California, Oregon, and Washington allow detached ADUs.