Brick Veneer in Cold Weather
Dear Tim: I have asked you for advice in the past and it was dead on - so I thought I would try you again. I am building a new home in Chicago. The problem is the timing might require brick work to be done in the winter months. I have seen this done at job sites around Chicago and all seems well. Some guys use tarps and heaters when applying the mortar and probably add some type of additive for the mix -- is this an acceptable practice? Is its skill dependent on the brick laying team? Finally, if I were to see failure in the mortar due to the weather, do you think it would occur within a year or something that would gradually occur and not become a significant problem for a few years? Maury P.
Dear Maury: Brick can be installed in cold weather but there are very strict guidelines as to how it should be done. The biggest problem is that the water in the mortar mix can freeze before it has a chance to develop into hard crystals that interlock the sand, cement paste and brick into one homogeneous unit.
There are additives you can blend in with the mortar mix to work at or slightly below freezing temperatures. These additives are very effective when used exactly as directed on the product labels. Problems happen when the masons stray from the temperature ranges that are suggested by the manufacturers.
Another trick real craftsmen use is to warm up every component used in the process. With proper planning, a tent can be built over all of the materials and the brick, sand, sacks of mortar and water are heated so they think it is 60 F or higher outdoors. Raising the temperature of all of the materials is very effective and can make all of the difference.
The best solution is to tent the entire house and create an artificial environment where the entire house and all of the materials think it is 45 - 55 F. This enclosure will be expensive to build and maintain, but if you leave it up for three days after the last brick is installed, you should never have problems.
If the mortar does freeze, failure will be immediately visible. The mortar will fall apart with little effort after seven days.