The National Association of Home Builders' monthly housing market index fell to a reading of 34 in July from 36 in June, compared with expectations for a smaller decrease to a 35 print in a survey compiled by Bloomberg.
The index was still above a reading of 33 a year earlier.
The readings for single-family sales, the six-month outlook and buyer traffic all declined compared with the previous month.
"With the HMI below 40 for 15 straight months, affordability remains the home building industry's primary challenge, as elevated mortgage rates, costly land, rising material prices, and persistent skilled labor shortages continue to affect the market," NAHB Chief Economist Robert Dietz said. "Looking ahead, the newly enacted housing law is a positive step that will help expand housing supply and lower overall housing costs, although more policy change is needed at the state and local level."