U.S. homebuilders are calling on the Biden administration to temporarily lift tariffs on China and Canada to ease supply-chain bottlenecks that are hurting housing affordability.

“Until a long-term solution can be reached, Congress and the administration should temporarily suspend duties on a wide array of imported building materials and goods, from Canadian softwood lumber to Chinese steel and aluminum,” National Association of Home Builders Chairman Chuck Fowke told lawmakers in comments reposted Wednesday on the group’s website.

“In addition, policymakers must continue to aggressively explore solutions to ease building material supply chain disruptions that are causing project delays and putting upward pressure on home prices,” Fowke said.

NAHB’s requests follow a volatile period for lumber, with prices quadrupling in the past year to reach a record high in May before cooling. While prices are down about 60% from this year’s peak, they remain above historical averages.

Higher lumber prices have raised homebuilding costs, while construction companies have had to postpone projects due to transportation and production delays of other materials. U.S. housing starts fell in September as lingering supply-chain constraints, labor shortages and higher materials costs challenged builders.