Exterior wall facings

The masonry on your façade serves, of course, a decorative purpose but it also ensures that the house structure is protected. It is therefore important that it be watertight and solid.

There are two types of covering material in Montréal: clay brick and limestone. They are both assembled the same way, by layering them with mortar joints and fastening them to the structural wall (which is usually made with 100 mm wood planks). Sometimes, bricks are used to make a solid masonry wall that is also structural. This is less common because the other construction method is simpler and, besides, more energy efficient.

As a matter of fact, the weak part of a masonry wall may lie in the quality of the mortar joints. Often, joints will erode with time or due to water infiltration. The assembly will weaken and sooner or later “bumps’’ or dislocated masonry elements appear (left picture). Sometimes, it may be the fasteners which will give way. One may also notice meandering cracks in the mortar, which indicates a weakening of the foundation wall or soil subsidence. Both cases must be attended to immediately with a construction professional or a competent mason (see the AEMQ web site www.aemq.com).

A GOOD QUESTION...
SHOULD YOU HAVE YOUR MORTAR JOINTS OR YOUR WALLET CLEANED?

It is rare that a wall needs to be dismantled completely. Because of the relatively small size of masonry elements (therefore offering a degree of flexibility), it is in most cases possible to repair only the part that presents a problem. Unfortunately, there are several “contractors’’ who present themselves as masonry work specialists. These unscrupulous amateurs will needlessly “attack’’ the mortar joints. Frequently, they will remove the mortar from some joints, or, even worse, they will fill the hollow joints with an assembly known as “line trig’’.

Hollow joints look good and it is saddening to see them disappear. In addition, these unruly repairs are done on portions only of a façade, which is a disaster aesthetically speaking (right picture). The quality of replacement mortar is also very important; a mortar with quicklime is better than a mortar with high cement content. This will ensure that the joints will remain “flexible’’. Caution is the word when the time comes to clean your façade for even if the result is spectacular at first, non-professional work will result in serious damage to the masonry if its surface, which has hardened and cured with time, is weakened. By becoming more porous, the wall will be more affected by the freezing and thawing cycles, which will accelerate its deterioration.

Masonry work should be done by artisans and competent masons. In order to assess precisely how much work is needed, don’t hesitate to call in a building inspector. Their expertise may cost you a few hundred dollars but it will save you a lot by limiting interventions on your walls to those which are necessary. Also respect original materials, don’t try to “modernize’’ your façade.