The Complete Guide to Working with Masonry in Cold Weather

As we move into the later months of the year, the issue of the temperature dropping can start to pose a real problem for contractors.

Cold weather can stop contractors working as laying brick becomes hazardous. Mortar freezes, wasting product and money. Newly laid bricks can be damaged as masonry doesn't set correctly in cold weather.

All in all, working with masonry in cold weather can be dangerous, and it’s essential that you follow cold weather masonry construction and protection recommendations.

Find out everything you need to know about cold weather, mortar and masonry below.

How cold can you work with mortar?

To meet the functional requirements of Chapter 2 of our Technical Manual, minimum working temperatures should never fall below 2°C when working with masonry. It is imperative that regular temperature readings are taking when working during cold weather periods.

Thermometers should be placed away from direct sunlight, preferably in a shaded area. It’s important to consider wind chill and weather exposure when assessing the temperature. Make necessary allowances for those sites which are deemed to have higher levels of exposure.

How to protect masonry units in cold weather

When working in cold weather, it’s important to follow cold weather masonry procedures to protect your product. This includes things like providing covers to protect your materials from frost, snow and ice. This is particularly true of bricks, blocks, sand and cement. Frozen materials should never be used when laying brick or in any circumstances. Always wait for temperatures to rise before laying bricks in cold weather. Cold weather can stop the bond between the mortar and brick setting correctly. This usually occurs at temperatures below 2°C.

Image of covered and thereby protected blockwork 

How to protect masonry work in cold weather

Any newly built walls or other masonry construction will require protection against frost where temperatures are expected to drop below 2°C. You should be protecting all masonry with polythene or hessian, ideally. If temperatures are expected to fall to an extremely low level, anti-freeze agents like insulation boards may be required and heated enclosures may even need to be considered.

Image of protected masonry walls

Finishes including rendering, plastering and screeds

Rendering should only be finished if the temperature outside is at least 2°C and rising. There should be no frost within the construction that is to be rendered and where possible, rendering should not take place where freezing weather conditions are anticipated prior to adequate curing.

It’s important to note that no plastering or screeding should take place unless the building is free from frost. It is acceptable to use internal heating to warm the building however it’s important to make sure that the heaters do not produce excessive vapour within the dwelling. Adequate ventilation should be provided to allow moist air to escape. The structure should be appropriately pre-heated before plastering and continue to be heated as the plaster dries.

For further information on working in cold weather you can download Chapter 2 of our Technical Manual:

The information used in this article is taken from Version 8 of the LABC Warranty technical Manual and is provided as guidance in meeting our technical standards. If working on an LABC Warranty site, please check which standards apply.

Please Note: Every care was taken to ensure the information in this article was correct at the time of publication on 5.3.2018. However, for the most up to date LABC Warranty technical guidance, please refer to your Risk Management Surveyor and the latest version of the LABC Warranty technical manual.