What is the Best Roofing Membrane for Winter?

When installing a flat or low-slope roof, you need to invest in a roofing membrane to withstand the harsh winters. That will help you protect your commercial property against such elements. So, what’s the best roofing membrane for winter?

This guide explores some of the best roofing membranes that can perform well during winter. You’ll also get to learn why winter is usually hard on roofing membranes. Finally, we’ll share a few tips on how to prepare and protect your flat roof from winter damages.

Let’s get started!

What’s the Best Roofing Membrane for Winter?

When looking for an excellent roofing membrane that can withstand the freezing temperatures during winter, invest in multiple-layered membranes. Single-layered membranes tend to be more vulnerable to heavy snowfalls.

Here are some of the best roofing membranes to withstand Canadian winters.

  1. Built-Up Roof Membranes (BUR)

This type of roofing membrane comprises alternating layers of reinforced materials and asphalt, creating a smooth finish. BUR membranes boast high tensile strength and water-resistant attributes, making them suitable for industrial and commercial roofing.

The good news is that the membrane can withstand the harsh winter weather. Its alternating layers of reinforcing fabric sheets and bitumen (coal tar or asphalt) are responsible for the membrane’s resistance to winter. Each of the layers is a ply.

Installation of BUR Membranes

Start the installation process by applying a base sheet to fasten it if a slope exists on the roof. A minimal slope must always exist to allow drainage.

You will then apply a layer of heated bitumen, which you have to follow immediately by reinforcing felt sheets. The felt will get coated or impregnated by bitumen to allow the heated bitumen to fuse with the sheets. Notably, the felt rolls are usually 3’-0” wide.

Finally, apply surfacing to offer protection and a spectacular aesthetic. This can be a final layer of asphalt spread across the entire roof or a mineral cap sheet integrated into the layers below. However, the most popular surface treatment is the aggregates.

Advantages of BUR Membranes

Built-up roof membranes have been in use for years and have an excellent track record in terms of performance. When properly installed and maintained, BUR membranes can last for up to 25 years. Deferred maintenance can diminish the lifespan significantly.

Disadvantages of BUR Membranes

The primary disadvantage is that asphalt bitumen products pose significant risks to the environment and the roofers installing them. Finding a leak on the BUR roofing system can also be tricky. You’ll have to remove the aggregates to access the watertight layers.

  1. Modified Bituminous Membrane Roofing

Modified Bitumen (Mod Bit) membranes are improved built-up roof systems and have been in use since the 1960s. The bitumen binder and reinforcing fabric are combined in a single roll to make the installation process more manageable.

Installation of Modified Bitumen Membranes

The membranes are usually installed on the roof in multiple layers of 2-3 plies to ensure water tightness. You can adhere or mechanically fasten a base sheet before installing a final surfaced sheet in a two-ply application.

When it comes to three-ply installations, you’ll install the base sheet then follow it by reinforcing ply. You’ll then cover it with the surface sheet. The surfacing offers extra protection and can be: adhered minerals, fine aggregates, or even liquid coatings. 

Advantages of Modified Bitumen Membranes

A significant advantage of the modified bituminous roofs over the BUR roof systems is their simplified installation process. That means they are less susceptible to issues. Also, the membranes have been in the market for decades, making them highly reliable.

Disadvantages of Modified Bitumen Membranes

Like the BUR roof systems, modified bituminous membranes are also hazardous to the environment. They also pose health risks to roofers due to the chemicals they contain and the fumes they produce. 

Why Winter is Usually Hard on Roofing Membranes

When the temperature is extremely low during winters, roofs with single-ply membranes tend to suffer the most due to heavy snowfalls. Some of the roofing membranes that usually experience most winter damages include PVC, EPDM, or TPO.

If you live in an area that experiences a dramatic fall in temperatures, you shouldn’t invest in single-ply membranes. They are usually more susceptible to extreme winters. A phenomenon known as “supercooling” can even exacerbate the impacts of winter.

“Supercooling” usually occurs when the membrane roof temperature gets colder than the ambient air temperature. The phenomenon is typically notable on clear moon nights when the thermal radiation gets emitted into space faster.

The occurrence will subject the roofing membranes to colder temperatures. When the temperature warms up during the day, the roof’s expansion and contraction will even be greater, increasing the risks of damages. This may compromise the roof’s structure.

Drainage Issues that Can Affect Roofing Membranes in Winter

Besides the impacts of fluctuating temperatures and damages from heavy snowfalls on a roofing membrane, uncorrected roof drainage issues can also threaten the integrity of membrane roofs. Here are some of the problems that can destroy roofing membranes.

Trapped Melt Water

Membranes roofs are usually designed to allow water to flow. But when the snowmelt becomes trapped after a heavy snowfall, it adds significant weight to the roof. If the roof was not designed to support the extra weight, the roof might collapse.

Ice Damming

When snow builds up on your roof during winter and melts partially in warmer dayparts, the meltwater will travel to your roof’s drainage system. When the temperature drops suddenly around the drainage areas, the melted water will refreeze to form an ice dam.

Frozen or Clogged Drains and Scuppers

When properly installed, the drainage systems on any roofing design will function well and efficiently. However, when the drains, scuppers, or gutters get clogged with a lot of debris, they will freeze, stopping or slowing the drainage rate.

Final Words

If you live in cooler areas, invest in the best roofing membrane to withstand the harsh climate. The good news is that you now know the best roofing membranes designed for winters, including the BUR and modified bitumen roofing systems. At Roof Master, we can help you with the installation process.

Contact us to talk to one of our roofing experts and get immediate help.

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