PRESCOTT, Ark. (AP) — Ninety workers will be laid off at the Firestone Building Products plant at the start of next month, company officials say.

The cuts represent a 21-percent employee reduction at the Prescott plant, which makes a synthetic rubber compound for roofing. They follow the layoffs of 71 plant workers in April.

Six salaried employees and 84 hourly workers will be among those laid off this time. Company officials said the cuts are to take effect Sept. 1.

Firestone Building Products is a subsidiary of Bridgestone Americas, based in Nashville, Tenn. The Japan-based Bridgestone Corp. bought Firestone in 1988.

Tina Gaines, spokeswoman for Firestone Building Products, said 437 workers remained at the Prescott plant after the April layoffs. She estimated the latest round would reduce the number of employees to 347.

In April, the company also announced layoffs of more than 50 employees at its Kingston, S.C., plant.

"The commercial construction market has been especially hard hit by the downturn in the economy, and the demand for roofing systems has fallen sharply," Gaines said. "The shift elimination and reduction of salaried employees was a very difficult decision to make but it was necessary to better align our human resources with the scale of our operations and to ensure the ongoing viability of our business."

The Prescott plant makes ethylene propylene diene monomer, or EPDM, a synthetic rubber roofing system commonly used in commercial construction. The facility is also a warehouse and distribution center.