Share of US Homes Built on Slabs Continues to Grow

The National Association of Home Builders (NAHB) recent analysis of the US Census Bureau’s Survey of Construction (SOC) reveals an interesting shift in the foundations new houses are being built on. According to the NAHB, 72.4% of new single-family homes started in 2023 were built on slab foundations, 16.6% were built with full or partial basements, and 9.9% with crawl spaces.

The share of new homes built on slabs has risen steadily from 45.8% in 2000 to 72.4% in 2023. The largest increase occurred from 2022 to 2023, with a jump of 3.9 percentage points, compared to an average increase of 1.93 percentage points over the previous five years. Conversely, the share of homes with full or partial basements decreased by 3.0 percentage points from 19.6% in 2022 to 16.6% 2023.

The NAHB explains that in colder areas where building codes require foundations to be built below the frost line, most homes are constructed with full or partial basements. In the northern divisions, full or partial basement foundations provide additional finished floor areas at a marginal increase of construction cost. The divisions with a majority share of full or partial basements in new homes are West North Central at 63.9%, followed by New England at 62.1%, Middle Atlantic at 48.1%, and East North Central at 48.0%.

The NAHB notes that interestingly, in East North Central, the share of homes with basements is now almost equal to those with slabs. The average area of finished basement was 1,128 sq. ft. in East North Central, 932 sq. ft. in the West North Central division, 890 sq. ft. in New England, and 1,117 sq. ft. in the Middle Atlantic. Nationwide, the average finished floor space of basements was 1,113 sq. ft. in 2023.