The average length of time to complete construction of a multifamily building, after obtaining authorization, is 16.2 months, according to the 2018 Survey of Construction (SOC) from the Census Bureau. The authorization-to-completion time has been on an upward trend since 2013.

The average time to build multifamily homes varies with the number of units in the building. In 2018, buildings with 20 or more units took the longest time (19.5 months) to build after obtaining authorization. Properties with 5 to 9 units required 16.7 months. 10 to 19 unit buildings finished in 15.9 months, and, lastly, 2 to 4 unit buildings came in at 12.1 months. Compared to 2017, it took longer to complete multifamily buildings with more than 4 units in 2018. It took additional 1 months to finish 5 to 9 unit buildings, additional 0.8 months for 10-19 unit buildings, and 1.9 months longer for buildings with 20 or more units. However, it was 1.4 months shorter to finish buildings with 2-4 units in 2018 than in 2017.

The 2018 SOC data also shows a significant regional variation in the average construction duration of multifamily buildings. The Northeast had the longest time from authorization to completion, 20.3 months, followed by the West, 17 months, and the South – 15.3 months. The shortest permit-to-completion period happened in the Midwest with 12.9 months.