The index, also known as homebuilder sentiment, came in at 58, unchanged from April, and missing the forecast for 59 according to Bloomberg.
"Builders remain cautiously optimistic about construction growth in 2016," said NAHB chief economist Robert Dietz in the release.
"Builder confidence has held firm at 58 for three consecutive months, showing that the single-family housing sector continues to recover at a slow but consistent pace," said NAHB chairman Ed Brady, who's also a home builder and developer from Bloomington.
"As we enter the spring home buying season, we should see the market move forward."
A spokesperson for the NAHB told Business Insider that the release was accidentally published ahead of the 10 a.m. release time because of an error by the web team.