Skyrocketing lumber prices that have tripled over the past 12 months have added $35,872 to the cost of an average new single-family home, according to new analysis by the National Association of Home Builders (NAHB), with the price spike threatening to hobble the momentum of the U.S. housing market, one of the bright stars of the recovery from the pandemic recession. While homebuilder sentiment remains optimistic, as indicated by the NAHB Housing Market index, headwinds due to rising building costs have pulled the index down from recent highs. “The supply chain for residential construction is tight, particularly regarding the cost and availability of lumber, appliances, and other building materials,” NAHB Chairman Chuck Fowke said in a statement. At the onset of the health crisis, “the mills stopped producing,” said Dustin Jalbert, senior economist and lumber industry specialist at Fastmarkets in Burlington, Massachusetts. “As soon as they saw 20 million unemployed, they shut down …