Creating Building Envelopes for Cold Weather
Working in cold weather areas means dealing with several challenging circumstances for the architects as well as the construction crews. Precipitation and freezing temperatures can cause significant harm to the building envelope’s structural integrity, resulting in discomfort for the occupants. Consequently, many different factors must be taken into account by the architects while planning and selecting the materials. Similarly, the construction crew must take adequate measures to ensure that severe weather conditions don’t lead to expensive delays. With adequate planning and preparation, it is possible for the stakeholders to complete building envelope projects within budget and on time, even in extremely old climate.
Lets us now discuss the importance of the planning phase in this context. Many experts feel that the best possible component of building envelopes for cold weather is WRB-AB or vapour-impermeable water-resistive and air barrier. However, this is not always the case. It is true that a WRB-AB is extremely efficient in preventing the external elements from entering inside the building. However, selecting a WRB-AB that doesn’t allow the escape of vapour from the building can cause serious structural issues for the envelope.
According to the laws of physics, moisture always tries to achieve the state of equilibrium by moving in specific directions. This is why it tends to migrate from warmer to colder and high pressure to low pressure areas. Therefore, in cold weather regions, the significantly lower outside temperature will result in the creation of a vapour drive. As a result of this vapour drive, the accumulated humidity and warmth inside the building will try to escape via the building’s exterior walls.
As a result of collection of moist air on cool surfaces, the air can easily form liquid water by condensation. This is extremely likely to lead to corrosion on metal assemblies, peeling paint, and growth of mold and mildew. This is why it is important to opt for a WRB-AB that is capable of blocking bulk water while allowing the passage of vapour.
In colder climates, another common concern is ice build-up. As water gets expanded in volume when it freezes, the structure of a building envelope may get severely damaged if water manages to enter inside the envelope. Accumulated ice and snow may also cause thermal bridging, allowing the escape of heat from the building interior through the thermal barrier. This will significantly reduce the overall energy efficiency of the building. This is another reason for selecting a WRB-AB that allows the vapour to pass, but keeps the cold air and water out of the building.
Timely Completion within Budget:
Schedule disruptions are common problems while working in cold-weather climates. One of the ways to remain on schedule regardless of weather is to specify products with an inherent capability to be used in cold weather. Silicone-based, liquid-applied WRB-Abs can be used in these climates. Sometimes, they also contain building wraps, bond enhancers, self-adhering membranes, anti-freeze additives, or other curing enhancers.
Please remember that even though these specialised products are suitable for cold-weather application, in order to be effective, it is important to apply them within a specific temperature range. Also, these products are not capable of accounting for certain changes that may take place overnight such as ambient temperature drop, accumulation of ice and snow, etc. Under both these circumstances, bond-inhibiting conditions are created. This can be a serious application issue with liquid-applied and self-adhering WRB-ABs. As an example, if the temperature is below the application range of the WRB-AB, a primer is required by the self-adhering membranes. Also, if they are applied in the presence of a layer of ice or snow on the sheathing, the adhesive may get brittle or cause the product to bond with ice or snow instead of the sheathing. In colder weather, liquid-applied products tend to move at a slower rate. This impacts their efficacy negatively and changes their absorption and curing profiles. This, in turn, can affect the application layer’s thickness. While it is tough to roll these products in colder climatic conditions, spraying is not a viable option because it can be dangerous for the workers.
In order to avoid costly delays caused by these extreme conditions, contractors often rely on tenting and heating for temperature regulation during the WRB-AB application process. However, naturally, the cost of renting the equipment and running the heater can be exorbitant. In order to remain exposed for to cold climate for longer durations, sheathing with integrated WRB-ABs is also an option. This may help overcome concerns related to temperature fluctuations and exposure to snow and ice.
At CGS Façade Group, we provide end-to-end support for all your building envelope related requirements. Since the inception of our company in 2005, we have completed numerous state-of-the-art building facades in all parts of the world. Regardless of where your next building envelope project is, contact us for world class engineering and craftsmanship.