As we explained in our last post about cold weather masonry work, the 40°F-mark is important when it comes to working with mortar. It’s important to keep the mortar heated above 40°F, but it’s understood that you can’t always control the air temperature (at least not easily). Here are some important steps to take if you’re doing masonry in winter:
- If the temperature is above 32°F, cover the walls with plastic to prevent water from getting into the masonry.
- If the temperature is between 32°F and 20°F, cover the walls with 1/2-inch insulation blankets to prevent or reduce rapid heat loss and to block water from getting into the masonry.
- If the temperature is between 20°F and 0°F, cover the walls with 1-inch, plastic insulation blankets, or maintain a heated area to 40°F for two days after the installation is complete.
It is important to only mix the mortar as you need it, so that it doesn’t become too cold before you use it. If the temperature of your mortar dropping too low becomes a concern, you can keep it warm by placing it on a heated surface, like a metal mortar board. Make sure that you keep an eye on your mortar if you’re trying to warm it, because excessive heat may dry it out.
The following tips apply for all masonry in winter being done in 40°F temperature or colder, or when the temperature of the masonry itself is below 40°F:
- Always heat sand or water to produce mortar above 40°F.
- You can use heat sources on either or both sides of masonry while it’s under construction.
- Install wind breakers if wind conditions exceed 15 miles per hour.
- Do not lay glass unit masonry in cold weather.
- Try to work inside heated enclosures when the temperature drops below 20°F.
- Beware of commercially-produced “antifreeze” admixtures for masonry work, because they are oftentimes just accelerators and not freezing-point depressants. Be sure that the admixtures that you are using are approved for the work you’re doing.
- If temperatures fall below freezing, and you experience frozen lumps in your work, you may need to heat sand in order to thaw the lumps.
- Always add cold sand to heated water in the mixer before adding cement to avoid flash setting.
- If masonry units are below 20°F, or have frozen moisture, visible ice, or snow on their surfaces, do not lay them.
- Although very high absorption fired-clay brick may need to be wetted prior to use, all masonry units should be kept dry before you’re ready to use them.