When installing masonry walls, there are two main choices that can apply. First, the so-called self-supporting masonry wall. This type of construction consists of laying the brick on a structural steel lintel serving as a foundation. The construction of these walls is subject to the National Building Code standard which limits the maximum height to eleven meters for small buildings.
The second choice is to use anchors attached to the interior wall, which will fully support the masonry. These anchors make it possible to erect stone or masonry walls, regardless of the height. In both cases, the cladding must be anchored to the interior wall. Since the facades are subject to the forces of the wind, the coating must be properly restrained to eliminate the risk of falling.
This standard defines the minimum loads that anchors must be able to withstand and the type of use for which they are manufactured. “Even though each project should refer to a structural engineer, the standard determines the minimum installation conditions. There are two subjects in particular that are unknown in this standard: firstly, the type of steel with which the anchors will be made and, secondly, the minimum acceptable resistance.
Type of steel
The type of steel used for manufacturing is standardized according to three levels of protection against corrosion. Level 1 is said to be factory galvanized. This type of fixing is used for interior walls only and in spaces that are not damp. This type of anchor should not be used for areas such as indoor pools, showers or washrooms. If there is water ingress into the wall even once, the risk of corrosion becomes great and weaknesses will form, making the fasteners no longer up to standard.
Level 2 requires a hot-dip galvanized finish. This protection offers good corrosion resistance. It is therefore possible to use these anchors for exterior walls and in humid interior spaces. This finish offers greater durability, especially if the construction is designed to minimize water infiltration.
Level 3 requires parts made of stainless steel. This provides unparalleled durability for corrosion resistance and coating support. It is also the one preferred for constructions over thirteen meters high in certain regions where the annual driving rain index is high.
Adjustable siding anchors offer an economical and flexible way to join masonry walls to a wood, metal or concrete structure, while allowing the installation of exterior insulation.
For the minimum acceptable resistance, the standard stipulates that each fastener must have a minimum breaking strength of 1000 newtons (force corresponding to 100 kg), and this, as much in compression, in tension as in buckling. The law also requires that the anchors be tested by an independent engineer to certify them. This regulation is the basis of the safety standard. This must be adjusted upwards according to the various constraints imposed by the climate and the architecture. For example, high-rise buildings in city centers are subject to wind corridor effects, which generate gusts that increase these stresses. The wind forces this strange phenomenon which is to create pressure on the surface receiving it and suction on the opposite side. This suction has the effect of pulling the coating outwards. In height, it is therefore necessary to increase the number of anchorages to reinforce the system, otherwise the risk of falling increases.
Now, why do some masonry walls fall? Falling bricks installed on anchors have been listed in several places. According to Mr. Vaillancourt, “it's mainly because of the corrosion of the anchors. The standards have changed over the past thirty years. In the past, it was permitted to install anchors made of level 1 steel. These rusted over time, thus weakening their resistance to the force of the wind”.
Although some building owners do everything possible to reduce construction and maintenance costs, Mr. Vaillancourt warns that one should never be negligent in the choice of anchors. “Masonry is a proven system that gives a beautiful architectural finish. In addition, the cost of the anchors is minimal compared to the total cost of the masonry. » The difference is not that big between the different types of bindings. For a level 1 fastener, you have to pay about $0.20 per square foot, while for a level 3 fastener, you have to count $0.75 to $1 per square foot. The price difference is significant, but beware, the installation of a level 1 anchor is not at all recommended outdoors and the anchors should be changed at least every twenty years, which is unthinkable in masonry. For $1 per square foot, that's peace of mind for many decades. “The quality of a building is not only apparent, it's what holds it all together that ensures the integrity of a structure for generations,” warns Mr. Vaillancourt. It is indeed an idea that deserves a good reflection considering that buildings have the potential to survive us for a long time.
Rigid anchors and insulators
It is not because this system is very durable that there is no evolution in the world of anchors. In recent years, owners and developers have increasingly wanted to install rigid insulation on the exterior wall in order to obtain good thermal insulation. As a result, the installation of the anchors is made more complex because the distance increases between the load-bearing wall and the covering and because it is necessary to cut the thermal bridges created by the installation of a piece of metal through the insulation. Moreover, the National Building Code updated in June 2020 the requirements for insulation and breaking thermal bridges (see FORMES , vol. 16, no 2, “Energy efficiency – Raising previous standards” , pp. 46-48). This element is now very important in the design. To meet this demand, it was necessary to rethink the design of the bindings and add a barrel with insulating washers to reduce heat exchange to a minimum.
The Thermal 2-Seal™ Wing Nut Anchor is a single screw anchor for use when insulation is already installed. It features a double-diameter cylinder with factory-installed EPDM washers to seal both the insulation face and the air/vapor barrier. Its thermal wings are designed to reduce heat transfer. Thermal wings are made from steel encapsulated in plastic to create a thermal break. The plastic is very flame resistant.
Thus, despite the apparently high price of certain types of anchors, we must not forget that it is in the durability of the work that the buyer finds his account. The standards are strict and it is not for nothing. Until homeowners and contractors are made aware of the best choice for their buildings, there will be tripping hazards. So, it is better to think twice, so as not to receive a brick on the head!