Lumber Liquidators’ sales plunge found a floor — but only by discounting.

The nation’s largest hardwood floor retailer said net sales slumped 12.8 percent last month after a March 1 “60 Minutes” report that raised health concerns over its Chinese-made laminate flooring.

The report found unsafe levels of formaldehyde, a carcinogen, in its China-sourced flooring products.

Same-store sales fell an even steeper 17.8 percent in March, but analysts said the decline was less than they’d been expecting.

Much of the sales decline appeared to come in laminate sales, which fell by about 20 percent in March.

Analysts noted that the sales decline that began in early March had slowed down, which caused the stock to rally early in the day. But a decline in gross margins was a worrisome trend.

“The company is clearly being promotional in stores with a $1 off per foot of Bellawood [its top-quality line] and nearly every other SKU on sale,” a Morgan Stanley analyst reported.

Analysts cite a move away from the more profitable laminate is putting added pressure on gross margins, which fell to about 35.5 percent, from 41.1 percent in the year-earlier period.

Total revenue rose 5.6 percent to $260 million in the first three months of the year. Analysts expected $256.8 million.

Shares ended up 19 cents, at $33.20, on Thursday.