With the end of 2018 approaching, NAHB’s Eye on Housing is reviewing the posts that attracted the most readers over the last year. In July, Na Zhao examined construction build times for single-family homes.

The 2017 Survey of Construction (SOC) from the Census Bureau shows that the average completion time of a single-family house is around 7.5 months, which usually includes almost a month from authorization to start and another 6.5 months to finish the construction. The average completion time in 2017 was the same as it was in 2016, but it was longer than the time needed in 2015 (7 months).

The time from authorization to completion varies across the nation and depends on the geographic location, metropolitan status, and whether the house is built for sale or custom-built. According to the 2017 SOC, it takes anywhere from less than a month to 77 months to build a single-family home from obtaining a permit to completion.

Among all the single-family houses completed in 2017, houses built for sale took the shortest time, 6.9 months from obtaining building permits to completion, while houses built by owners required the longest time, 12.3 months. Homes built by hired contractors normally needed around 9 months. A large proportion of single-family homes built for sale and custom homes built by contractors on owners’ land began construction within the same month after obtaining building authorizations. However, custom homes built by owners serving as general contractors had a one-month lag between obtaining permits and construction start in 2017.

The average time from authorization to completion also varies across divisions. The division with the longest time was New England (10.4 months), followed by the Middle Atlantic (10.3 months), East South Central (9.4 months), East North Central (8.2 months) and Pacific (8.5 months) in 2017. These five divisions had average time from permit to completion exceeding the nation’s average (7.5 months). The shortest period, 6.4 months, is registered in the South Atlantic division. The average waiting period from permit to construction start varies from the shortest time of 17 days in the Mountain division to the longest one of 39 days in Pacific.

Houses in metropolitan areas, on average, took nearly 7.3 months to completion, which was 2 months shorter than those in non-metropolitan areas. This pattern was quite consistent across the nation, except for the West North Central division where the average time to completion in metropolitan areas was longer than in non-metropolitan areas in 2017.

The SOC also collects sale information for houses built for sale, including the sale date when buyers sign the sale contracts or make a deposit. Looking at single-family homes completed in 2017, 31.6% was sold before construction started, 28.8% sold while under construction, 11.3% sold during the month of completion, and 16.6 % sold after completion. The percent of single-family houses completed in 2017 and remaining unsold as of the first quarter of 2018 was 11.6%.