Ice Dam Prevention for Steep-Slope Roof Systems

In the middle of winter with snow falling outside, you can’t help but notice how the snow collects on steep-slope commercial buildings. Yes, snow piles up on top of roofs and gets very heavy, but piles of snow aren’t necessarily the biggest thing to worry about. It’s what happens to the snow as it melts that can really cause issues with your roof assets.

Indications of larger issues include a lack of snow as compared to other locations, or an excessive build-up of snow overtop latent ice at low eave conditions. Collateral damage at the eaves, including damaged sheet metal components, stained overhangs and interior leakage can oftentimes tell the story of a roof system in need of improvements.

What Are Ice Dams and How Do They Form?

Steep slope roofs are typically water-shedding coverings and rely on a waterproofing underlayment. Ice dams are the result of having a “warm” attic space, which causes a temperature differential between eave and ridge conditions. Interior heat melts the snow, then the melted snow (liquid water) is then covered with additional snow and the snow can turn to ice as temperatures drop.

Hydrostatic pressure builds up at these areas due to accumulation overtop of the melted snow and can back up underneath the roof covering and breach the underlayment, creating undesirable conditions – such as interior leaks, stained soffits, damaged finishes, etc. Repeated freeze-thaw cycles cause a thick buildup of ice to form at the edge of the roof system over the eaves, which can cause icicles to form.

The buildup of water, ice and snow on the roof surface can force its way under the roof covering or through vulnerable joints in the roof surface, penetrating the building envelope and entering the building’s interior environment.

To put it simply:

• Snow and ice collect on the roof.
• Snow and ice start melting from the highest parts of the roof and drain downward.
• Areas near the edge of the roof can remain cold,  with snow and ice accumulation remaining intact, blocking water drainage.
• Melted snow and ice collects at the cold edges of the roof, causing it to refreeze.
• A heavy collection of snow and ice can form at the edges of the roof, potentially threatening the roof’s structural integrity. This can also lead to leakage into the interior space, and damage both interior and exterior finishes.

It’s no surprise that once any part of your building envelope is compromised, the interior assets follow suit. Water that penetrates the roof can then seep down into the walls, insulation and flooring, damaging important assets, interrupting operations/production and destroying irreplaceable records.

How To Prevent Ice Dam Formation

Ice dam formation is very common in any geographical area that experiences snowfall and wide temperature variations. Ice damming is preventable, but if this is an occurrence at your facility, you may need professional assistance. Considerations for mitigating ice damming include:

• Assess Roof Insulation and Ventilation – A well-insulated/ventilated roof will have less “warm” spots than a poorly insulated one. A regular assessment will tell you whether the insulation/ventilation is sufficient or needs improvement. It’s all about keeping the attic space “cold” and limiting thermal shorts in the insulation envelope.
• Invest in De-Icing Cables – If ice dams are an ongoing problem for your building, you might consider investing in an engineered de-icing cable solution that can be installed at low eaves, gutters and downspouts. This can be a common practice for those who have perennial issues.
• Plan for Remediation During a Reroofing Project – If an assessment shows that it’s time to replace your roof system, a reroofing project is a great opportunity to evaluate the ventilation and waterproofing material selection. Proper ventilation would be a key to lowering the underdeck temperature while smarter material selection can help prevent/mitigate structural damage if ice-damming reoccurs.

Stop Spending. Start Investing.

Technical Assurance is your partner for total roof management. Our programmatic approach to building envelope asset management aims to reduce emergency spending and reactive repairs by providing annual assessments and implementing preventative maintenance programs. We can help you find and invest in the right solutions to help prevent, mitigate or remediate ice damming on your commercial roof.

Moisture management is key to maintaining the integrity of your roof system. You can also learn more about uncontrolled rainwater penetration and moisture ingress here.

If you’re having trouble with ice dams on your commercial roof system, we can help you better understand the issue, offer solutions, and manage and maintain your valuable assets. Contact us to request a free consultation!