Homebuilder optimism remains limited, despite historically low mortgage interest rates as demand just isn't there, according to the latest National Association of Home Builders index. The NAHB and Wells Fargo (WFC) survey builders to gauge perceptions of the new, single-family home market for the next six months. A score higher than 50 indicates more builders view the market as good than poor. The index slid to 14 for September from a revised reading of 15 for August. The index has stayed within 13 to 17 for 12 months. NAHB Chairman Bob Nielsen said "very little has changed in terms of housing market conditions so far this year." "Builders continue to confront the same challenges in accessing construction credit, obtaining accurate appraisal values for new homes, and competing against foreclosed properties that they have seen for some time," according to Nielsen. He said the downgrade of America's debt by Standard & Poor's and congressional gridlock on the budget deficit hurt homebuilder and consumer confidence in recent weeks. Earlier Monday, Lennar Corp. (LEN) said its third-quarter earnings fell 31% from a year earlier on 2.9% fewer homes delivered. The Miami-based homebuilder said third-quarter orders increased 11% to 2,914 homes. David Crowe, chief economist for the NAHB, said the extended, low, narrow range of the trade group's index "reflects builders' awareness that many consumers are simply unwilling or unable to move forward with a home purchase in today's uncertain economic climate." "While some bright spots are beginning to emerge in about a dozen select metro areas, the broader picture remains fairly bleak due to the weak economy and job market," Crowe said. The part of the NAHB survey that gauges expectations of sales over the next six months fell two points to 17, while the component that tracks prospective buyers declined two points to 11. The component gauging current sales conditions fell one point to a reading of 14 for September. Write to Jason Philyaw. Follow him on Twitter: @jrphilyaw