Protect Your Flat Roof from Winter – What You Need to Know

  • October 12, 2022
  • Joel
  • Minute Read

    Aside from the difficulties of keeping yourself safe and warm during the cold winter months of Colorado, if you own a building - your home or office - the problem gets worse. Winter can be very hard on a roof, especially one that is already showing signs of wear and tear. But what is it about the winter that can be so tough on your roof?

    Icicles hanging from the edge of a roof.

    Winter is brutal on a flat roof.

    Two of the most common causes for premature roof failure, especially for flat roofs in cold climates, are temperature fluctuations and ice.

    Learn why this is the case and what you can do about it to protect your flat roof.

    Even in the Colorado winter, it is not uncommon for the daytime high temperatures to reach 50 degrees (or more) and then at night the temperature dips to freezing (or lower). This fluctuation in temperature is called thermal shock - and called "shock" for good reason.

    When the temperature gets warmer the building's structure, including the roof, begins to expand. Then when the temperature gets colder, the building's structure begins to contract. The more extreme the temperature fluctuation is, the greater this expansion and contraction that takes place. All of this puts tremendous strain on a roofing structure.

    Thermal Shock and Your Flat Roof

    Think of your roof like a rubber band. Take a rubber band and hold it out in front of you - one side in your left hand and one side in your right hand. Now begin to pull your hands apart, stretching that rubber band close to what you think the breaking point is and then let it go slack again. Keep doing that several times and you'll notice several important things:

    1. What you may first notice is that the rubber band begins to loose its tensile strength, taking less and less effort to stretch it. In effect, it gets to its breaking point much sooner.
    2. After only a few stretches, you'll also notice that the rubber band does not contract back to its original position anymore. Having lost its tensile strength by the constant expansion and contraction, that rubber band will never attain its original shape or strength again.
    3. Lastly, you might have noticed that if you stretched and loosened, i.e., expanded and contracted, the rubber band enough times, eventually it will break, and over time it takes a lot less strain to get it to that point.

    Even though a rubber band is designed to address these types of extremes, it will eventually fail if stretched enough times.

    Temperature fluctuations can work your flat roof like a rubber band

    Your flat roof can be worked like a rubber band throughout the year, causing premature failure

    Now, think of the same stresses on your roof with the constant expansion and contraction that takes place - sometimes severely so - from the effects of thermal shock and even wind.

    A roof is not necessarily designed for such extremes, and so its breaking point is not only assured, but the breaking point itself may be a lot sooner than you think.

    Also, as an older rubber band will fail much more quickly than a new one, so goes an old and deteriorating roof. Failure can happen exponentially sooner than that of a new roof. Temperature, or specifically temperature fluctuations in this case, work your roof like that rubber band.

    The more the temperature fluctuation, the more that rubber band (your roof) must stretch and relax to accommodate. This will weaken the structural integrity of your roof. In fact, as you may have guessed, this thermal shock can also happen in the height of summer

    For example, in Colorado, the daytime high temperature can easily reach 90 degrees, with the evening low temperature dropping into the 50's. That's a 40-degree temperature fluctuation - in a single day! This is not good for your roof. Now do that over and over and over, throughout the year, with even wider fluctuations thrown in for good measure.

    Every day, every night - day after day, season after season, year after year. This toll on your roof is significant. Expansion joints crack and separate, seams tear loose, roofing materials break down and deteriorate, and on and on. The end result is a failing roof. The results could be catastrophic.

    The Damaging Effects of Ice

    While ice is more specific to wintertime conditions, it is also one of the most destructive elements that your roof will likely encounter. Why? When it snows on your roof, oftentimes the first layer of snow melts as it comes into contact with the relative warmth of the building.

    That "liquid snow" gets into your roof's cracks and crevices. Then as the snow continues to fall, the wet, watery snow underneath begins to freeze. When it freezes, that moisture within those cracks and crevices expands. This expansion makes any defects in the roof worse.

    Now what happens when you get a warm day and a bulk - if not all - of the rooftop snow begins to melt? The process is started all over again. Because now the newly melted snow seeks out and finds additional cracks and crevices. Then when the temperatures drop again during the night, that water freezes and expands again.

    Similar to thermal shock, this constant freezing and thawing of snow and ice exacerbates defects in the roof. The older and more damaged your roof, the more profound the freeze-thaw-freeze effect will have.

    So your roof will encounter thermal shock as well as the expansion and contraction related to freezing and thawing. The cycles are unavoidable and only vary by degree of severity. While Florida may see significant thermal shock (especially after a rain the drastically and immediately reduces a roof's temperature), the Colorado climate must battle the severe consequences of not only thermal shock, but the freeze-thaw cycle.

    Protect Your Flat Roof - Reduce the Negative Effects of Winter

    So what can you do to reduce the negative effects of these destructive processes?

    One thing you can do is to start out with a white, highly-reflective roof. This will reduce the thermal shock to more reasonable levels. Another thing is to make sure that there is adequate drainage on your roof so that any rain or snowmelt is able to get off of your roof before it is able to freeze (or refreeze as the case may be). See also Is a Black Roof Better than a White Roof?

    Ultimately every roof is different and exists in a unique local environment. All of this makes it impossible to put the same "fix" to every roof.

    Every roof is different. But two of the best products to consider to prepare your roof for winter are the Duro-Last single-ply roofing system and the roof retoration line of products from American WeatherStar.

    Therefore, the best way to know your roof's specific needs is to have your roof evaluated by one of our qualified inspectors. We offer roof evaluations and can provide you with specific and significant insight into the needs of your particular roof.

    Contact Us today!


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