Lumber prices in Chicago rose to new record highs Tuesday, with uncertainty about wood supplies hitting at a time when the building products are most in demand.

It’s peak home-building season in the U.S., and that’s clashing with a lumber supply chain that’s being dogged by everything from trucking delays to worker shortages.

“Clearly lumber prices, which are at historical levels, have entered a frenzied stage,” said Joshua Zaret, a senior analyst at Bloomberg Intelligence. “It’s all being driven by supply, and just the uncertainty of supply right now.”

The pandemic has left Americans with a bigger-than-usual appetite to buy new homes and do renovations, which is behind the quadrupling of lumber costs this past year. Builders who need wood for spring construction are struggling to find it, so they’re going to the futures market and pushing prices to new highs, said Brian Leonard, lumber analyst for RCM Alternatives in Chicago.

There’s still such a thing as too expensive. The market saw wild swings on Tuesday, with prices rising and then falling by exchange limits.

“We needed to get to a price where the buying stopped,” said Mike Wisnefski, chief executive of MaterialsXchange in Chicago.

Speculators with long positions may also have taken profits, contributing to the sudden price declines, said Stinson Dean, chief executive officer of Deacon Lumber Co.

The July futures contract rose by the $48 exchange limit to $1,334.60 per thousand board feet, an all-time high, before briefly falling by the same limit to $1,238.60 on the Chicago Mercantile Exchange.

Prices settled up 3.9% to $1,286.60.