Mortar Industry Association (MIA) part of the Mineral Products Association (MPA)


mortar industry association



Hot and cold weather working

Masonry construction in both hot and cold weather conditions requires consideration as to how these conditions may affect the quality of the finished masonry. In some cases, extreme weather conditions may warrant the use of special construction techniques or protective measures to ensure that masonry work is not adversely affected.

Summer working

Evaporation of water from the mortar is the primary concern in hot weather. If sufficient water is not present, the bond between the mortar and masonry unit may be reduced. However, the increased rate of hydration of the cement and favourable curing conditions in warm, humid weather will help develop masonry strength if sufficient water is present at the time of construction.

More detailed information can be found by clicking here to go to the MIA learning text, part 11, Construction (see Summer working).

Winter working

Mortar hydration and strength development occurs at temperatures of greater than about 4°C. This means that when the temperature at the time of laying is less than about 4°C, the characteristics of the mortar may be affected. Consequently, masonry construction should be discontinued when the air temperature falls below 3°C, unless the mortar temperature can be maintained at a minimum of 4°C until it has hardened; this may necessitate working in heated enclosures. If suspended, laying may be resumed when the air temperature rises to 1°C and is expected to continue rising to above 3°C over the bricklaying period.

For more detailed information go to the MIA data sheet No 7, Factory-produced mortar for use at low/freezing temperatures or go to the MIA learning text, part 11, Construction (see Winter working).

MIA data sheets

No. 7 Factory-produced mortar for use at low/freezing temperatures

MIA learning text

Part 11 Construction (see ‘Summer and winter working’)

Part 13 Best practice – potential site problems (see ‘Freeze/thaw cycles and frost attack’)

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