(July 10, 2024) -- The National Association of Home Builders reports that nearly two-thirds (65%) of new single-family detached homes sold in 2023 were built on lots under 9,000 square feet, less than 1/5 of an acre. According to the latest Survey of Construction (SOC), this is the highest share on record and reflects stark changes in the lot size distribution over the last two decades. In 1999, when the Census Bureau started tracking these series, less than half (46%) of new for-sale single-family detached homes occupied lots of that size.A shift in speculatively built (or spec) homes towards smaller lots continued despite the pandemic-triggered suburban flight and presumed shifts in preferences towards more spacious living. The steadily rising share of smaller lots undoubtedly reflects unprecedented lot shortages confronted by home builders during the pandemic housing boom and their attempts to make new homes more affordable.
Zooming in on lots smaller than 7,000 square feet (or 0.16 of an acre) reveals another record reading, as the share of these lots reached 40% in 2023. In sharp contrast, only 28% of new single-family detached spec homes were built on lots of that size in 1999, when the Census started tracking these data.
However, a persistent shift towards smaller lots is a more recent phenomenon. The share of lots under one-fifth of an acre fluctuated around 48%, never crossing the 50% mark until 2011. It was only during the last decade that the share rose rapidly, from 50% in 2011 to 61% right before the pandemic, and gained an additional four percentage points during the last four years.
A closer look at the lot size distribution since 2010 shows that the most dramatic shifts took place at the lowest end, with lots under 0.16 acres increasing their share by 13 percentage points. In 2010, 27% of all sold single-family detached homes occupied lots under 0.16 acres, and an additional 20% were on lots between 0.16 and 0.25 acres. Fast-forward to 2023, and these shares increased to 40% and 25%, respectively.
At the other end of the lot size distribution, the share of spec homes built on larger lots exceeding half an acre shrunk from 14% in 2010 to 9% in 2023. The share of lots measuring between a quarter and half an acre declined from 24% to 18% over that time span.
The median lot size of a new single-family detached home sold in 2023 now stands at 8,400 square feet, or just under one-fifth of an acre. This is slightly larger but statistically not different from the lowest on record median of 8,177 square feet set a year before the COVID-19 pandemic.
While the nation’s production of spec homes shifts towards smaller lots, the regional differences in lot sizes persist. Looking at single-family detached spec homes started in 2023, the median lot size in New England is almost three times larger than the national median.
New England is known for strict local zoning regulations often requiring very low densities. Therefore, it is not surprising that single-family detached spec homes started in New England are built on some of the largest lots in the nation, with half of the lots exceeding 0.56 acres. The East South Central division is a distant second on the list, with the median lot occupying just under a third of an acre.
In the South, the West South Central division stands out for starting half of single-family detached spec homes on lots under 0.15 acres. This is half the size of typical lots in the neighboring East South Central division.
The Pacific division where densities are high and developed land is scarce has the smallest lots, with half of the lots being under 0.14 acres. The bordering Mountain division also reports typical lots smaller (0.16 acres) than the national median.
The analysis above is limited to single-family detached speculatively built homes. Custom homes built on an owner’s land with either the owner or a builder acting as the general contractor do not involve the work of a professional land developer subdividing a property. Therefore, in the case of custom homes, lots refer to an owner’s land area rather than lots in a conventional sense. Nevertheless, the SOC reports lot sizes for custom homes and shows they tend to have larger lots. The median lot size for custom single-family detached homes started in 2023 is one acre.
For the regional analysis, the median lot size is chosen over the average since averages tend to be heavily influenced by extreme outliers. In addition, the Census Bureau often masks extreme lot sizes and values on the public-use SOC dataset, making it difficult to calculate averages precisely, but medians (as the midpoint of a frequency distribution) remain unaffected by these procedures.