Hot Weather Masonry-Performance of Units

General. When considering the influence of masonry units on construction during hot

weather, one should recognize that the absorption (suction) of units may vary dependent

upon their exposure at the project. Units that have been heated and dried by the sun will

absorb more water from the mortar than units kept shaded.

High absorption units can contribute to rapid dry-out of mortars in hot weather. Wetting

of high absorption fired clay units prior to use will reduce this tendency to dry out the

mortar. Concrete masonry units should not be wetted before use, but concrete masonry

can be covered with wet burlap or water sprayed after walls are constructed to assure

adequate curing moisture.

Summary. Unit temperatures and absorption characteristics affect the properties of masonry

constructed during hot weather. Shading units during storage, wetting high IRA fired clay units,

and water spraying or covering clay or concrete masonry walls with wet burlap after construction

are methods of compensating for the effects of hot weather on unit properties and masonry performance.

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

Hot & Cold Weather Masonry-Publication of Masonry Industry Council