Hurricanes Irma and Harvey are changing builder D.R. Horton's forecast for cash-flow from operations, its backlog conversion rate and certain expenses as a share of revenue.

Fiscal 2017 estimates for the backlog conversion rate are now 85%, down from a previous estimate of 88%-90%; selling, general and administrative expenses will likely make up 8.6% of revenue rather than 8.3%-8.4%; and cash-flow from operations is forecast to be $150 million as opposed to $300 million.

The fiscal 2018 guidance the builder issued in July remains unchanged.

Among other builders that find the storms are affecting their business is Lennar Corp., which recently warned that there would be delays in new-home deliveries as a result. The company has 40% of its revenue concentrated in the Southeast and Texas, which have been hard hit by the storms.

While the storms are slowing sales, the scarcity of inventory that results from the hurricanes puts upward pressure on home prices.

Overall, builders are growing slightly more pessimistic due to the storms.

On a scale of 1-100, homebuilder sentiment was 64 this month, according to the National Association of Home Builders and Wells Fargo. The previous forecast for the September index level was 67. Last month, the revised index was 67.

Lenders also are struggling with challenges due to storm-related delays in pending home sales, particularly Hurricane Irma, which affected more than 90% of mortgaged properties in Florida.

Servicing businesses also are under pressure due to the hurricanes. Delinquencies were much higher in the areas affected by Hurricane Harvey, for example.