Methods for manufacturing pre-fabricated insulated foam wall structures with high racking strength and related pre-fabricated wall structures

A method of manufacturing a high racking strength pre-fabricated insulated wall structure comprising:

• (a) spray applying a polyurethane foam-forming composition into a cavity of a wall structure, wherein the wall structure comprises:
• i) a first member;
• ii) a second member spaced apart from the first member;
• and
• iii) connecting members extending between the first member and the second member, wherein the first member, the second member, and the connecting members each comprise a front surface and a rear surface that form the front frame surface and a rear frame surface;
• and
• iv) a foam panel attached to the front frame surface, such that foam panel, the first member, the second member, and the connecting members define the cavity within the frame;
• and
• (b) allowing the polyurethane foam-forming composition to expand within at least a portion of the cavity to form a polyurethane foam layer deposited in the cavity,
• wherein the polyurethane foam layer is formed in-situ during the manufacturing method, and
• wherein the density of the polyurethane foam layer is 3.0 to 4.0 lb/ft3 when measured according to ASTM D1622-08 and the wall structure is disposed in a climate-controlled spray application station throughout the spray applying wherein the relative humidity and dew point of the air in the climate-controlled spray application station is controlled throughout the spray applying so that the wall structure has a racking strength of at least 500 pounds per linear foot (2224 N).