apparatus and product of this invention have the following advantages 1 the foam mixture is smoothed into the fiberglass mats by the rotating hexagonal bar before it begins to react cream 2 most of the foam mixture is held between the two fiberglass mats so that it can be transported to the substrate while rising and curing 3 the fiberglass becomes an integral reinforcing within the urethane foam 5 trapping the foam mixture between the two flat non woven mats helps to mold the foam into a flat profile as it rises and cures 6 the fiberglass mat reinforcing is inexpensive and restrains the foam so as to make it more dimensionally stable under temperature and humidity changes 7 boardstock can be readily removed from a release surfaced conveyor belt after curing to a tack free condition removal from the belt is facilitated by the much higher bond strength of foam to glass mat vs foam to release surface 8 an additional layer of fiberglass mat can be introduced into the process for additional reinforcing 9 the foam mixture that remains on the top mat forms a smooth skinned surface the smooth skin facilitates bonding of protective sheeting or membranes to the surface and imparts additional compressive strength to the foam surface 10 the hexagonal bar rotating is easily cleaned off by pulling out a few inches of fiberglass mat.