Ice Damming 101: How to Combat Ice Dams on Metal Roofs
We’re no stranger to cold weather in Montana. Icy gales, heavy snowfall, and double negative degree weather are all part of the winter experience.
However, ice dams on your metal roof are a chilly occurrence you shouldn’t have to face. Ice buildup on your roof can lead to costly long-term damage and diminish your metal roof’s value. At Great Northern Metal Company, we’ve seen the toll ice dams can take on a metal roof, so we want to arm you with the knowledge for how to stop ice dams in their tracks.
If you’re in Montana and concerned about an ice dam forming on your roof or want to ice dam-proof future metal roofing projects, you’re in the right place. Keep reading for our experts’ solutions.
What is an Ice Dam?
An ice dam is a ridge of built up ice that forms at the edge of a metal roof, preventing melting snow from draining off. They usually form after a bout of heavy snowfall or extreme cold and can be found on the lower portions of roofs or gutters.
Ice dams form through repeated cycles of freezing and thawing. The snow collects on the roof, melts, then collects on a lower portion of a roof where it is colder or not well insulated. There, the ice steadily builds up and creates a heavy ice barrier. This phenomenon is very common in cold climates like Montana’s, particularly on sloped metal roofs or the North and East angles of roofs where sunlight is sparse.
What Causes Ice Dams?
The main cause of ice dams is the uneven heating of your roof. This is typically due to poor attic insulation and ventilation. When the upper areas of your roof remain above freezing, snow melts and flows down to the colder eaves, where it refreezes and forms an ice dam. Other contributing factors include:
- Heat loss from the house
- Snow accumulation on the roof
- Complicated designs on the North and East aspects of the roof
- Outside temperatures that consistently stay below freezing
What Damage can Ice Dams Cause?
If left to build up, the fallout of ice dams can be extensive and expensive. When ice dams build up, the standing water on your roof can leak into your building. These leaks can ruin the insulation in your attic, leading to increased energy costs, mold, and mildew growth. Also, water infiltrating the building’s structure can stain and damage ceilings and walls, peel paint, and warp floors.
On the outside of your building, ice dams can wreck your roof’s metal panels. Ice expands when it forms, which can damage the seams of panels and pull trim apart. This can lead to you needing to replace metal panels, which can be both time consuming and expensive. Ice dams often form in gutters and, if severe enough, can cause your entire gutter to fall from the weight of buildup. Also, damage to your gutter can lead to fascia damage, such as stripping the paint and even tearing it down.
In short, it’s better to prevent ice dams now rather than to have a costly headache in the long run.
Ice Dam Prevention Tips
To stay on top of ice dams, you must consider four factors: design, heat loss, roof ventilation, and maintenance. By taking into account each of these aspects, you can keep your roofs free from ice dams and long-term damage. Here are some actionable tips to help you protect your metal roof:
Design
- Consider the Slope of Your Roof: If you are designing or building in a cold climate, make sure your roof’s slope accounts for the risk of ice damming. Metal roofs with steeper slopes drain snow, ice, and water more effectively. Typically, a slope over 3/12 is best for shedding water.
- Install Oversized Gutters: Installing larger gutters can help reduce the risk of ice damming by accommodating a greater flow of melting snow and water. This ensures the water drains freely and prevents ice buildup. However, if you upgrade to bigger gutters, you may need to account for this change in the rest of your roofing design. Bigger gutters may necessitate larger downspouts and stronger supports to manage the increased load and maintain system integrity.
Heat Loss
- Enhance Attic Insulation: Upgrading your attic’s insulation is a fundamental step in preventing ice dams. Effective insulation helps maintain a uniform temperature across the roof, preventing the snow on the warmer upper areas of the roof from melting and then refreezing at the colder eaves. This not only reduces the risk of ice dams but also improves the overall energy efficiency of your building.
- Install Heated Cables: Heated cables installed along the edges of your roof can be an effective proactive measure. These cables heat up the areas where ice dams typically form, ensuring that any water from melted snow flows off the roof instead of refreezing. It’s important to install these cables before the winter season begins and to ensure they are correctly positioned and secured to be most effective.
- Seal Air Leaks: Sealing air leaks from the living spaces below the attic is another critical measure. Warm air that escapes into the attic can cause uneven temperatures on the roof, facilitating ice dam formation. Use caulking or foam insulation to seal around light fixtures, pipes, chimney passes, and other potential leak sites in the attic.
Ventilation
- Improve Ventilation: Proper attic ventilation is critical in maintaining a cool roof temperature by allowing a natural flow of cold air. Soffit and ridge vents should be installed to create a balance that pushes warm air out while drawing cold air in. This balance is crucial for minimizing the amount of snow melting on the roof due to heat from the attic.
Maintenance
- Clear Snow from the Roof: Regularly removing snow from your roof dramatically lowers the risk of ice dam formation. Use a roof rake after heavy snowfall to clear the first three to four feet of the roof edge where ice dams typically form. This prevention method is especially crucial during deep freeze cycles. If you’re unable to safely remove the snow yourself, consider hiring professionals.
- Regular Maintenance and Inspections: Schedule annual or bi-annual inspections with a professional to ensure your roof and attic insulation are in good condition. These inspections can help catch potential problems like deteriorating insulation or blocked ventilation before they lead to ice dam formation. Regular maintenance checks also help extend the life of your roof by ensuring that minor issues are addressed promptly.
Cold Weather Resources
If you’re braving the harsh Montana winters, maintaining your metal roof is crucial. Dive into our range of articles tailored to help you keep your roof in top condition:
Get Expert Advice from Great Northern Metal Company
Want to ensure your metal roof stands up to Montana’s harsh winters? At Great Northern Metal Company, we don’t just supply high-quality metal roofing and siding. We provide valuable insights and expert advice on the best practices for metal roofing, including preventing ice dams.
Contact us today to learn how our products can enhance your roofing projects and help you manage Montana’s winter challenges. Let’s work together to keep your roof safe throughout the snowy season.
What Is Sealant for Metal Roofing?
Metal roof sealant helps seal seams, joints, gaps, and other areas where water or air could enter a roofing system. Most gun-grade sealants are applied from a tube and form a bead over or within a joint. Depending on the formulation, the material may remain permanently pliable or cure into a flexible seal.
For metal roofing, flexibility matters. Panels naturally move as temperatures rise and fall, so a sealant used at a moving joint needs to accommodate that movement without losing adhesion.
The location of the seal matters too. A product used at an exposed seam may need different properties than one placed inside a concealed joint.
Sealant also should not be treated as a substitute for proper flashing, fastening, or panel installation. It works as part of the roofing system, not as a fix for a detail that was built incorrectly.
What Is Butyl Tape for Metal Roofing?
Butyl tape is a preformed sealing material typically installed between two roofing components. Instead of applying a bead from a tube, the installer lays a continuous strip of tape along the joint before the materials are fastened together. That makes it especially useful at concealed laps and other locations where two metal surfaces come together.
Butyl stays flexible, which helps it maintain a seal as a metal building experiences normal movement. There are also expanding sealant tapes that serve a similar purpose while filling irregular gaps and accommodating movement within the joint.
Sealant vs. Butyl Tape
The simplest way to think about the difference is application.
Gun-grade sealant works well when you need to apply a bead into a seam, joint, or gap. Butyl tape works well when you need a continuous seal between overlapping or adjoining components.
One is not automatically better than the other. The roof detail determines which type makes sense.
Metal Roof Sealant vs. Butyl Tape: Which Should You Use?
Different roof details put different demands on the sealing product.
These are general guidelines. Always check the roofing-system requirements and the manufacturer’s installation instructions before choosing a product.
4 of the Top Metal Roof Sealants and Butyl Tapes
The right product depends on the joint, expected movement, temperature conditions, and whether the seal will be exposed or concealed.
Here are four options GNMC has tried, tested, and trusts so much that we chose to carry them at our shop.
Best for: Expansion joints, lap seams, and joints that need to accommodate movement.
EMSEAL AST Hi-Acrylic Sealant Tape is a self-adhering, open-cell polyurethane foam tape impregnated with acrylic-modified asphalt.
Unlike a standard flat tape, EMSEAL AST gradually expands after it is removed from its packaging. That allows it to conform to the joint and fill gaps along irregular surfaces. For metal roofing and metal buildings, that can be particularly useful around details affected by thermal expansion and contraction.
Why It Works Well With Metal Roofing
One of EMSEAL AST’s biggest advantages is its ability to move with the building. The tape conforms to contours and maintains a seal as metal panels expand and contract. It is designed to help keep out dust, air, wind-driven snow, and moisture through joint details.
It also does not dry out and become hard or brittle over time. Because the material remains compressed within the joint, it is designed to stay in place rather than squeeze out the way some caulks or butyl products can.
Its resistance to UV exposure, aging, and mildew also makes it well suited to demanding exterior applications.
Common Applications
EMSEAL AST can be useful for:
- Expansion and compression joints
- Lap seams
- Mechanically fastened joints
- Irregular gaps
- Metal building details where movement needs to be accommodated
It can also be used alongside several common building materials, including metal, plastic, wood, and concrete.
Interested in EMSEAL AST? Contact GNMC
Best for: Metal panel joints that need a permanently pliable, gun-grade sealant.
TFC BUTYL™ is a single-component butyl-based sealant designed specifically for strong adhesion to metal panels.
Its biggest distinction is that it remains permanently pliable. It does not skin over into a hard surface, which allows the material to continue moving with the joint after installation.
Why It Works Well With Metal Roofing
Metal panels do not stay perfectly still over the life of a building. Temperature changes create movement, and joints need a sealing product that can handle it.
TFC BUTYL remains flexible and moisture-resistant, which makes it useful for metal panel details where a rigid sealant would not be appropriate.
It also meets or exceeds AAMA 809.2 and is available in gray or white.
Installation Matters
Good adhesion starts with a clean surface. Before applying TFC BUTYL, the substrate should be dry and free from frost, oil, grease, incompatible coatings, or other contaminants that could interfere with adhesion.
The product is applied using a standard caulking gun and can be tooled after application if needed.
It is also worth paying attention to storage. TFC BUTYL should be kept in a controlled, dry environment below 75°F and used within 12 months of manufacture.
One other detail to know before choosing it: TFC BUTYL is not paintable.
Ask GNMC about TFC BUTYL™.
Best for: Seams, panel joints, and gaps that need a flexible cured sealant.
NovaFlex Metal Roof & Panel Adhesive Sealant is a single-component silicone sealant and adhesive commonly used as a seam sealant or joint filler in metal roofing and panel systems.
It is non-corrosive and non-sag, making it useful where contractors need a gun-grade product that will stay where it is placed.
Why It Works Well With Metal Roofing
Temperature range is one of NovaFlex’s standout characteristics. The product can be applied at temperatures from -20°F to 160°F and has a service temperature range of -40°F to 400°F.
That broad range is useful for metal roofing, where surfaces can experience substantial temperature swings.
NovaFlex also offers good adhesion to common building materials and can bridge gaps up to 3/8 inch. Its exterior weathering and aging performance make it suited to exposed building applications.
Where NovaFlex Makes Sense
Contractors may consider NovaFlex for:
- Metal roof seams
- Panel joints
- Joint filling
- Small gaps
- Details exposed to wide temperature swings
It remains flexible at temperatures down to -10°F and is freeze-thaw stable. There are a couple of limitations worth knowing before installation. NovaFlex is not recommended for joints that will be submerged underwater, and it should not be used on surfaces that will later be painted.
Cure time also depends on temperature and humidity, so installers should account for site conditions and follow the product instructions.
Contact GNMC about product availability.
Best for: Concealed metal building joints that need a continuous, flexible seal.
MB-10A Butyl Tape is an elastomeric butyl rubber sealant specifically designed around the requirements of metal buildings.
It comes extruded on silicone-coated release paper, which makes it straightforward to position during installation. It is also produced in different sizes and lengths to suit a range of applications.
Why It Works Well With Metal Roofing
MB-10A is designed to maintain its seal through normal building movement. Its combination of adhesive strength and cohesive strength helps the tape stay together and stay bonded as the assembly moves.
Temperature performance is another important benefit. MB-10A is designed to withstand extreme roof temperatures while maintaining compressibility in colder conditions. It also offers resistance to UV light and cold flow.
Those characteristics matter on metal buildings, where the material may experience a wide range of temperatures throughout the year.
Common Applications
MB-10A may be a good fit for:
- Concealed panel laps
- Metal building joints
- Overlapping components
- Details requiring a continuous butyl seal
- Joints affected by normal building movement
Choosing the right tape size is important. The joint needs enough material to create the intended seal without using so much that the tape squeezes excessively out of the detail.
Inquire about MB-10A Butyl Tape
What to Consider Before Choosing a Metal Roof Sealant
Before grabbing a tube or roll, look at what the joint actually needs and ask yourself the following questions:
- How Much Will the Joint Move? Metal panels expand and contract as temperatures change. A sealing product at a moving joint needs enough flexibility to accommodate that movement.
- What Temperatures Will the Product See? Metal roof surfaces can get hot, and Montana projects can also see very cold conditions. Check the product’s application temperature separately from its service temperature. A sealant may perform across a wide temperature range once cured while still having specific limits for installation.
- Is the Joint Exposed or Concealed? A concealed panel lap has different needs than an exposed seam. Butyl tape is often a practical choice where two materials are compressed together. A gun-grade sealant may make more sense when a seam or gap needs to be filled from the outside.
- What Materials Is the Product Touching? Always check compatibility with the metal substrate and any adjoining materials. A product that adheres well to bare metal may have different requirements around painted finishes, other coatings, plastics, or masonry.
- Will the Surface Be Painted? Some sealants are not paintable. Both TFC BUTYL and NovaFlex have limitations that should be understood before choosing them for a detail that will receive a finish later.
- What Does Installation Require? Good products still need good installation. Surface preparation, storage, bead size, compression, and cure time can all affect the finished seal. Read the product instructions before installation instead of assuming every sealant or tape works the same way.
Frequently Asked Questions About Metal Roof Sealants and Butyl Tape
What is the best sealant for a metal roof?
The best metal roof sealant depends on where it will be used. Gun-grade sealants can work well for seams and joints, while butyl tape is commonly used between overlapping components or in concealed joints. Movement, temperature, substrate compatibility, and exposure should all factor into the decision.
Is butyl tape good for metal roofing?
Yes. Butyl tape is well suited to many metal roofing details because it creates a continuous seal between components while remaining flexible enough to accommodate normal building movement.
Is sealant or butyl tape better for a metal roof?
Neither option is better for every application. Butyl tape is often used inside laps and concealed joints, while gun-grade sealants are useful for filling seams, joints, and gaps. Some details may use both as part of the roofing system.
Does metal roof sealant need to stay flexible?
For joints that experience movement, flexibility is important. Metal panels expand and contract as temperatures change, so the sealing product needs to accommodate the expected movement without losing adhesion.
Can you use any silicone sealant on a metal roof?
No. Use a sealant that is compatible with the roofing material, coating, joint design, and expected temperatures. The product instructions and roofing-system requirements should guide the choice.
Need Metal Roof Sealant or Butyl Tape for Your Next Project?
Great Northern Metal Company carries EMSEAL AST, TFC BUTYL™, NovaFlex, and MB-10A Butyl Tape for a range of metal roofing and metal building applications.
Tell our team what detail you are working on and what you need the product to do. We can help you review the options GNMC carries and get the right product information before you place an order.
Inquire About Metal Roof Sealants
