Tag: ventilation

How to Prevent Ice Dams on Metal Roofs

Posted on by Ken Buchinger

Those in areas prone to below-freezing temperatures are likely familiar with ice dams and the costly damage they can cause. With winter weather already upon us, it’s important to ensure your building is protected against the dangerous and expensive effects of ice dams.

What Causes Ice Dams to Develop?

Most ice dams are a result of building air barrier flaws. When warm indoor air escapes through a rooftop, it warms the roof sheathing. This rise in temperature melts the underside of the layer of snow on top. The melted snow then moves down the slope of the roof toward the eaves, where it freezes into ice. As this process continues, the ice thickens, resulting in ice dams. These obstructions can cause water to back up and form a reservoir that can damage ceilings.

Ice Dams | ABC Blog

How Can Ice Dams Be Prevented?

To prevent ice dams, follow these four steps:

  1. Seal Air Leaks: Sealing air leaks between the warm building interior and the attic or ceiling is imperative to prevent increased sheathing temperatures that can lead to ice dams. If your roof leaks every winter, it’s likely that an air leak is to blame. And, getting a new roof is not likely to help—even if it features more ventilation. The simple way to determine if you have air leaks is to get into your attic and check. Leaks can likely be easily sealed with two-component polyurethane spray foam. And extending any exhaust fans that don’t reach outside can help adequately seal the structure.
  1. Ensure Proper Insulation: Many buildings don’t have adequate insulation levels to prevent ice damming. Building codes based on your geographic location can help you determine how much insulation you need. If the structure’s design doesn’t allow for adequate insulation, we recommend installing as much closed-cell spray polyurethane foam as possible. If replacing your roof, you can also install additional rigid foam insulation on top of the existing roof sheathing before you install the new roof. When taking that approach, make sure all products used are compatible with your new roof and adhere to manufacturer’s recommendations. It’s also imperative that attic insulation completely covers the top plates of a building’s exterior walls.
  1. Improve Ventilation: Improving ventilation alone will not prevent air leaks that cause ice damming and should never be your first or only defense. In fact, improving ventilation without sealing air leaks and installing adequate insulation can increase heating costs and make ice damming problems worse. Despite this, if combined with steps one and two above, addressing your roof ventilation can’t hurt. The best ventilation options include soffit and ridge vents. It’s important to remember that all attic ventilation systems require an insulation dam (blocking) between the trusses and ventilation baffles at the attic’s perimeter, facing the soffits, to maintain a ventilation channel from the soffit to the attic and protect against wind-wash.
  1. Use Underlayment: Covering your roof sheathing with two or more layers of rubberized membrane underlayment is another protection method that is far less effective if not used in concert with steps one and two. To use properly, it should extend from roof eaves to a point that’s three feet higher than your exterior wall.

Additional measures like framing your roof with raised-heel trusses can also help prevent ice dams. Additionally, avoiding including valleys as well as gutters that are at or above the roofing plane is ideal. Taking these steps can help ensure people and property are safe from overhead dangers. This should be a priority when designing, installing and maintaining your metal roof.

For additional information on how metal roofs perform in winter weather, read part one and part two of our ‘Metal Roofs and Snow’ blog series. For additional tips on how to winter-proof your roof, reach out to a local ABC representative today.

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Proper Ventilation for Metal Roofs and Walls

Posted on by David Lester

Selecting metal roof and wall panels is a strategic investment for the life of a building. To protect their investment, it is key that your customers ensure the proper ventilation system is installed. Optimal air movement not only promotes temperature regulation and energy efficiency but also reduces the risk of moisture-related issues like condensation build-up. Here, we look at some of the main ventilation considerations and resources your customers need to ensure success.

ABC Blog: Proper Ventilation of Metal Roofs and Walls

Why is proper ventilation important?

Proper ventilation helps optimize the performance and efficiency of metal buildings by:

  1. Controlling condensation

Condensation can wreak havoc on metal, causing corrosion, reduced thermal performance of insulation, mold and mildew growth, and even insect infestations. For example, in warm and humid areas, outside air that enters a building without moving through a ventilation system can bring with it large amounts of humidity. This humid air can create an uncomfortable environment, accelerate panel weathering and increase the possibility of mold growth. This issue is worsened when the outside temperature falls below the inside temperature, creating a perfect breeding ground for condensation development.

  1. Regulating temperature

Regulating and maintaining ideal interior temperature can help cool the building in warmer months, keeping the structure comfortable to occupy. Temperature regulation also helps protect the integrity of the building from excess (and premature) metal panel expansion and contraction. This movement can weaken the integrity of fasteners, which are designed to keep panels from detaching/pulling away from the substrate.

  1. Preserving air quality inside the building

Proper ventilation helps remove volatile organic compounds and other air pollutants that are detrimental to human health and productivity. The Environmental Protection Agency (EPA) and the Occupational Safety and Health Administration (OSHA) have published guidance on indoor air quality standards in commercial/institutional buildings. These standards help determine ventilation needs that need to be met to ensure compliance.

Who Needs Ventilation?

As expected, most structures require proper ventilation in accordance with their geographic location, contents and/or building end-use. Structures housing chemicals or moist substances require more ventilation than those storing dry goods in relatively arid environments. Ventilating a building that stores ceramic in the desert is very different than ventilating an indoor sauna in practically any geographic location. Agricultural facilities in particular must employ proper ventilation to mitigate the dangers posed by ammonia and other corrosive airborne fumes. (See our Animal Housing blog post for more.)

How to Ensure Proper Ventilation:

Similarly, the ideal amount and type of ventilation your customers need depends on their building’s unique specifications and end use. Generally, structures larger than 2,400 sq. ft. may require more than one type of ventilator to allow air to move between them (cross-ventilation). Structures that house people, animals and/or valuable material also benefit from cross-ventilation using ridge vents near the roof and a louver vent located closer to the structure’s floor. In these cases, it is recommended that your customers work with design professionals and building engineers who can help determine the building ventilation requirements. These professionals can recommend the appropriate, high-quality metal panels and components that suit the unique requirements of their project.

So, what ventilation options are available for your customers? Ventilation solutions fall into two main categories: natural (unpowered) and mechanical (electrically assisted):

  • Natural ventilation methods include installing a ridge and eave vents that enable air to circulate naturally through the building. Your customers can also use vents that capitalize on the natural vacuum created when air moves quickly over angled surfaces like roofs. The lower pressure in this vacuum draws air out of the building—most often through ridge vents. This choice will depend on your customer’s aesthetic preferences and/or installation location limitations.

 

  • Mechanical or power-assisted ventilation helps draw more cubic feet of air into and out of the space per minute. Powered fans with curved blades and/or louvers are often used to achieve greater air flow. As previously noted, air flow is vital in preventing condensation, so this is particularly helpful in naturally humid environments.

Conclusion

In conclusion, proper ventilation is a critical component of any high-quality building. As metal panels are becoming more popular, understanding how to achieve an effective ventilation system can help ensure the success of your customers’ building projects.

For more on ABC’s ventilation solutions, visit our previous blog on condensation management, check out our ventilation-enabling components or reach out to your local representative today!