An improved board material is provided comprising a set cementitious core bearing on at least one of its surfaces as a facer a multilayer nonwoven fibrous mat of a specific structure. The outer layer of the mat comprises fibers of a fine diameter of approximately 1 to 10 microns and the inner layer of the mat comprises coarser fibers having a greater diameter (e.g., approximately 12 to 30 microns and preferably approximately 15 to 20 microns). The outer surface is relatively smooth and is aesthetically pleasing. The coarser fibers of the inner surface provide interstices between adjoining fibers so as to promote the ingress of the cementitious core prior to setting with the achievement of enhanced adhesion between the set cementitious core and the multilayer nonwoven fibrous mat.