Common misconceptions about reinforcing fiberglass mesh

Fiberglass is composed of tiny glass fibers that are produced when glass that is heated and extruded into extremely thin threads, a process that’s been used for many centuries. The application of this production into the material that we know today as fiberglass began in the late 1930s.

Several types of silica with different chemical properties are used to make fiberglass. Some have a high acid resistance, more tensile strength, or are produced based on their different possible applications. Fiberglass is an extremely stiff, durable and flexible material touted for its strength that is used in many common everyday items such as skis, hockey sticks, hunting crossbows, and medical casts for broken limbs.

The reinforcing fiberglass mesh is an extremely necessary component of Exterior Insulation Finishing Systems, and it is composed using regular, plain glass, the same that is used in the manufacturing of products like glass bottles. There are come misconceptions about the reinforcing fiberglass mesh used in EIFS, and these misconceptions can lead to improperly installed EIFS or mistakes that can prove costly down the road.

Common mistakes when applying the mesh include:

Choosing not to use mesh throughout the whole wall cladding. The mesh used in EIFS is a pivotal part of the overall strength of the whole system. If the mesh is only applied at the insulation board joints to compensate for the expanding and contracting at these points, the areas of the EIFS where reinforcing mesh is not found are left quite weak and vulnerable to exterior impact.

When EIFS is used, it may often be next to or encroaching on a non-EIFS wall. Normally, the cementitious base coat is extended between these two walls and further onto the non-EIFS wall. However, both of these walls may shift at different rates, which would yet again lead to cracking and other problems because of excess strain on the reinforcing mesh. Inserting a caulking joint can be an effective way to rectify this problem.

Another mistake is using improper tools in the application of the mesh. One of the biggest detriments to fiberglass mesh used in EIFS is when its structural integrity is compromised during the application process. Glass is a brittle material, meaning it would rather shatter than bend if hit with something. The tiniest bumps or nicks on the surface of the mesh can significantly reduce its effectiveness and durability and cause it to break, which can result in eventual cracks in the lamina. Using a better-suited trowel to apply the mesh in details, such as one with a plastic insert that won’t cut or harm the mesh, solves this problem effectively.

Poor solutions to common problems and misconceptions:

A major problem thought to be prevalent with the fiberglass reinforcing mesh used in EIFS is that the alkaline substances that are found in the most commonly used form of cement used on the planet, Portland cement, can abrade tiny imperfections within the surface of the fiberglass – the cement used in the base coat can actually harm the structural integrity of the mesh. The alkali comes from within the cement when it reacts with humidity or moisture. Alkali-resistant glass is available, but it is extremely expensive and infeasible for EIFS purposes as it negates one of the largest benefits of using EIFS, that being cost-effectiveness.

Plastic mesh is available as a potential solution to the alkali cement dilemma. It’s resistant to the chemical properties of cement and will not react the same way, but it also stretches more than fiberglass and will melt at the high temperatures observed in a typical house fire. These qualities are far less desirable than the alkaline-resistance it offers and place limits on where it can be used.

The reality of these problems affecting EIFS: They don’t.

EIFS have been designed and developed to be suited to Canadian climates and homes, and protect against problems those climates may face that do not apply elsewhere. As such, most reinforcing mesh is made of fiberglass that is coated in a plastic resin, which keeps it strong, stiff, and resistant to the alkali properties of any cementitious base coat. This resin may be clear or coloured, depending on specifications.

The extremely high working strength of glass, more so than even steel, is significantly outshone by its readiness to shatter easily. The brittleness of glass is not a factor in the reinforcing mesh, because of the way fiberglass is manufactured. The material properties of the glass have been reworked so that the immense strength remains, but it will not break easily. It will not stretch either, which means it will not allow itself to be overworked to the point of breakage that would crack the lamina, cracking that would lead to a series of problems that could eventually snowball out of control.

These misconceptions about the fiberglass reinforcing mesh also only arise when the EIFS is modified for cost because of competition or an advantage over another in price. Components being removed or made of different materials will only reduce the durability and effectiveness of EIFS that is already perfectly suited for homes in Ontario and across Canada.

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