The nation’s biggest homebuilder trade group is calling on newly installed Commerce Secretary Gina Raimondo to take action on the high cost of lumber that it says is threatening housing affordability.

Along with 35 other organizations, the National Association of Home Builders sent Raimondo a letter on March 12 calling her to turn her “immediate attention to an issue threatening the economic recovery and housing affordability: the price of lumber. We respectfully request that your office examine the lumber supply chain, identify the causes for high prices and supply constraints, and seek immediate remedies that will increase production.”

Lumber prices have nearly tripled in the last year, the letter says, and oriented strand board prices are up more than 250 percent.

“These spikes have caused the cost of building an average new single-family home to increase by more than $24,000 since mid-April 2020 according to the National Association of Home Builders standard estimates of lumber used to build the average home,” the letter states. “Similarly, the cost of the average new multifamily unit has increased by $9,000 over the same period due to the surge in lumber prices. Additionally, lumber and engineered wood products such as OSB are a large and important component of residential and commercial remodeling projects, such as hospitals, schools, offices and restaurants.”

Because many builders sign fixed-price contracts, they have to absorb any materials costs. If the price increases are sustained, the letter warns, it could make certain single-family and multifamily construction projects unviable.

The NAHB recently released survey data showing that most single-family homebuilders in the Northeast are struggling with supply chain issues, from price to timeliness of deliveries, even as demand for single-family homes skyrockets amid record-low interest rates and the coming of age of a large cohort of Millennials looking to buy their first homes or upgrade to a home sized to their growing families.