Hot Weather Masonry – Planning Construction

General. As previously noted, hot weather influences the properties of mortars and units

as individual materials and it affects the interaction between mortar and units that occur

in the construction of masonry. The rates of stiffening and setting of mortar are increased,

while hot, dry units exhibit high suction characteristics. Relative humidity, wind velocity,

and sunshine are additional factors that affect the moisture loss during and after

construction. Unless proper planning, preparation, and construction procedures are used,

hot weather can impede productivity and compromise the quality of masonry

Planning should include a consideration of scheduling to avoid construction during hot,

mid-day periods and a review of the requirements for materials. Provisions need to be

made to protect and prepare masonry materials for use. Modifications to construction

procedures may include wetting high absorption clay units, reducing the length of mortar

spread before placement of units to minimize elapsed time between spreading mortar and

placing unit, covering masonry after construction, and/or fog spraying with water.

Summary. Planning, preparation, and procedures for hot weather masonry construction

should focus on assuring that mortar remains workable from the time of mixing until

placement of units, and that sufficient moisture remains in the masonry to provide for

normal strength development of the mortar. Available avenues of achieving these goals

include scheduling construction to avoid hot, mid-day periods, optimizing selection and

preparation of masonry materials, protecting constructed masonry from sun and wind,

damp curing masonry by covering with wet burlap, or fog spraying with water.

Resource: Masonry Institute of St. Louis – www.masonrystl.org

Hot & Cold Weather Masonry-Publication of Masonry Industry Council