Share of Homes Built on Slabs Surges to 72.4%

NAHB analysis of the Survey of Construction (SOC) shows that 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 (pp), compared to an average increase of 1.93 pp over the previous five years. Conversely, the share of homes with full or partial basements decreased by 3.0 pp from 19.6% in 2022 to 16.6% 2023.

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 (63.9%), followed by New England (62.1%), Middle Atlantic (48.1%), and East North Central (48.0%). 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 square feet (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.

In warmer climate where slab foundations are preferred for their cost-effectiveness, new homes with slab foundations are most commonly found in the West South Central (96.9%), Pacific (86.5%), South Atlantic (83.3%), and Mountain (52.9%) divisions. However, adoption rates for slab foundations are also increasing in northern divisions. The figure below shows the share of slab foundations for these four divisions have risen from less than 15% in 2000 to over 30% in 2023. Notably, there is a knee in the curve in 2020, indicating that supply chain disruptions and building material prices brought about by the pandemic contributed to the switch to slab foundations. Another factor is the increased use of frost-protected shallow foundations (FPSF), introduced in 2000, that also enhances affordability.