The disclosed invention consists of an improved gypsum based, cellulosic containing
board and method for applying a resin to an untreated board at a spray station
where pMDI resin is sprayed onto the front and back side of the board. A resin
distribution system is used to supply the spray nozzles with pMDI. Optionally,
a second spray station is included, if desired, to add additional pMDI resin over
the surface of the board to achieve complete coverage. The improvement is an increased
water resistance and flexural strength.