When cold weather comes, many masonry contractors decide not to work, intimidated by the extra preparations required. Materials must be kept warm to be useable. Masons must be warm to work efficiently. The finished masonry work must be protected from freezing or risk expensive damage. All this costs more. Owners are willing to incur these additional costs to have their buildings ready for occupancy in the spring when most tenants relocate. For masonry contractors, working in cold weather can bring additional income. Aside from the uncomfortable working conditions, cold weather affects masonry construction in two ways. It slows hydration of the portland cement in the mortar, and it can cause damage when water in the mortar freezes. For these reasons, work procedures must be adjusted in cold weather. 25 tips for maintaining masonry quality in these conditions are presented.