Hot Weather Masonry Construction

Finally – the hot summer months are
upon us! Now is the time to remind
you of the key considerations for
masonry work in hot, dry and windy
weather conditions.

Key Challenge: Mortar Cracks!

A common complaint during the summer months is the appearance of fine cracks in mortar joints that appear up to a day or two after construction. These cracks are generally caused by mortar that has not cured properly. This can be the result of insufficient water available for the cement (in the mortar) to cure or by materials (masonry units, mortar constituents) that are too hot at the time of construction, causing ‘flash set’ of the mortar.

Recommended Solutions:

Pre-dampen the product
With Arriscraft products, we recommend that you pre-dampen the units. Using a hose, simply allow water to run over the skids of units for up to 30 minutes, depending on the configuration of units on the skids. This dampening can be done on the previous day, but should be done at least five hours prior to the units being used. Following this timeframe will ensure that the units are reasonably wetted, but surface dry at the time of laying.

Use proper mortar mix
Remember that the choices of mortar type and the individual mortar materials are very important.
The use of a 1:1:6 portland cement-lime mortar, when properly combined with the appropriate quantity of water, will produce a general-purpose mortar exhibiting good workability and board life in its plastic state and good durability and flexibility in its hardened state.

The use of only Type S hydrated lime will give better water retention properties to the plastic mortar.

Protect all materials
Properly covering all materials will help to reduce heat build up, minimize dust contamination of masonry units and control high moisture loss. Remember to ensure that the sand pile is kept in a moist condition. Dampen the sand pile if needed at the end of each day.

Adjust your installation as needed
When it is hot outside, use cool equipment and pre-soaked mortar boards. Limit the spread of mortar to 1.2 m (4 ft.) and place units within one minute of spreading the mortar. On sunny days, masons should work and move with the shade when practical and possibly start working earlier in the morning.

The use of wind screens, water/fog sprays and wall coverings at the end of the day will slow the rate of moisture loss from the masonry.

Download our Quick Reference Guide here. To discuss these guidelines, or for any other questions, give us a call at 1-800-265-8123.