WASHINGTON — Confidence among U.S. homebuilders dropped to a 15-year low this month as sales slowed and profits dropped, according to a survey released yesterday.

The National Association of Home Builders/Wells Fargo index of builder confidence fell to 30 in September from a revised 33 in August, the Washington-based association said. A reading below 50 means most builders view conditions as poor. It was the eighth consecutive monthly drop in the index.

Profits are dropping for builders as they offer incentives such as stainless steel appliances to entice buyers. The housing slump is curbing economic growth and will let Federal Reserve policymakers keep interest rates unchanged as they meet this week, economists say.

The confidence survey asks builders to characterize current sales as "good," "fair" or "poor" and to gauge prospective buyers' traffic and their expectations for the next six months.

A measure of sales expectations for the next six months fell to 37 from a revised 41 in August. The index of buyer traffic held steady at 22. The index of current sales dropped to 32 this month from 37. All three index readings were also the lowest since 1991.

Confidence fell in three of four regions this month, with the biggest decrease in the Northeast, where the index dropped to 28 from 34. The index fell to 38 from 43 in the West and dropped to 38 from 41 in the South. The confidence index for the Midwest was unchanged at 16.