A method for adhesively sealing a joint or a surface in or on a building structure that is in contact with chlorinated water, includes the steps: applying a primer composition P onto the surface or into the joint to be sealed; waiting for primer composition P to be cured; applying a moisture-curable sealant composition S onto the cured primer composition P, thus sealing the joint or the surface; and curing the moisture-curable sealant composition S by means of moisture; wherein said primer composition P comprises: at least one polyol and at least one polyisocyanate, or a polyurethane reaction product thereof, and at least one organic solvent; and wherein said moisture-curable sealant composition S includes: between 10 and 60 wt.-%, based on the total composition S, of at least one organic polymer having hydrolysable silane groups, and at least one silane curing catalyst.

A method for adhesively sealing a joint or a surface in or on a building structure that is in contact with chlorinated water, includes the steps: applying a primer composition P onto the surface or into the joint to be sealed; waiting for primer composition P to be cured; applying a moisture-curable sealant composition S onto the cured primer composition P, thus sealing the joint or the surface; and curing the moisture-curable sealant composition S by means of moisture; wherein said primer composition P comprises: at least one polyol and at least one polyisocyanate, or a polyurethane reaction product thereof, and at least one organic solvent; and wherein said moisture-curable sealant composition S includes: between 10 and 60 wt.-%, based on the total composition S, of at least one organic polymer having hydrolysable silane groups, and at least one silane curing catalyst.

Disclosed are hydrophobic finish compositions and cementitious articles made with the hydrophobic finish compositions. In some embodiments, the article is a waterproof gypsum panel surface reinforced with inorganic mineral fibers that face a flexible and hydrophobic cementitious finish possessing beneficial waterproofing properties. The waterproof gypsum panels of the invention have many uses, such as, tilebacker board in wet or dry areas of buildings, exterior weather barrier panel for use as exterior sheathing, and roof cover board having water durability and low surface absorption. The flexible and hydrophobic cementitious finish can include fly ash, film-forming polymer, silane compound (e.g., alkyl alkoxysilane), an extended flow time retention agent including either one or more carboxylic acids, salts of carboxylic acids, or mixtures thereof, and other optional additives.

Disclosed are hydrophobic finish compositions and cementitious articles made with the hydrophobic finish compositions. In some embodiments, the article is a waterproof gypsum panel surface reinforced with inorganic mineral fibers that face a flexible and hydrophobic cementitious finish possessing beneficial waterproofing properties. The waterproof gypsum panels of the invention have many uses, such as, tilebacker board in wet or dry areas of buildings, exterior weather barrier panel for use as exterior sheathing, and roof cover board having water durability and low surface absorption. The flexible and hydrophobic cementitious finish can include fly ash, film-forming polymer, silane compound (e.g., alkyl alkoxysilane), an extended flow time retention agent including either one or more carboxylic acids, salts of carboxylic acids, or mixtures thereof, and other optional additives.