| abstract |
A cementitious board (100) and a method of manufacturing the cementitious board (100) has a cover layer (105) having a surface weight of about 300 grams / M2, and an air permeability index of no more than about 300 CFM. / ft2 (test method FG 436-910). The cover layer 105 reduces the penetration of a cementitious material grout (29) during the manufacture of the board (100) and passes water vapor from the grout (28) while the grout (28) cures. Binders, coatings or impregnants (107) decrease the pore size, increase or decrease the contact angle of liquids, promote adhesion to cementitious cores (101), promote adhesion to the cover layer (105) and promote the adhesion or affinity to adhesive compositions used to bond cementitious boards to exterior insulation systems and exterior finishing systems (EIS and EIFS). |