When installing a metal roof, you're investing in a durable, long-lasting, and often energy-efficient system. However, even the most robust metal panels have gaps and openings – primarily along their corrugated profiles or at their termination points. This is where closure strips become an essential, albeit often overlooked, component. Ignoring them can undermine your roof's integrity, leading to unexpected problems down the line.

What are closure strips? Purpose & materials

Closure strips are specially designed foam or sometimes metal pieces that are used to seal the open voids or "flutes" within metal roofing panels.

• Purpose:

  • Preventing Water Intrusion: Their primary function is to block wind-driven rain, snow, sleet, and even fine dust from entering the gaps between the metal panels and the underlying roof structure. Without them, moisture can easily blow up and under the panels.

  • Pest Exclusion: They act as a critical barrier against insects (like wasps, bees, and spiders), birds, rodents (mice, squirrels), and other small animals that seek shelter or entry points into attics and wall cavities.

  • Noise Reduction: Foam closure strips can offer a degree of sound dampening, reducing the "drumming" noise that rain or hail can sometimes create on metal roofs.

  • Thermal Barrier: They help minimize air leakage, contributing to better insulation and energy efficiency by preventing conditioned air from escaping and unconditioned air from entering the attic space.

  • Aesthetic Finish: By filling the voids, they give the roof edge a cleaner, more finished appearance.

• Materials:

  • Foam (most common): Made from durable, closed-cell polyethylene or similar foam materials. They are often cross-linked for enhanced durability and resistance to temperature extremes, chemicals, and UV radiation. Foam strips are custom-cut to perfectly match the profile of specific metal panels (e.g., specific corrugated patterns or standing seam profiles). Many come with an adhesive backing for easy installation.

  • Metal (less common for closures, more for vents): While not typically used as primary "closure strips" to fill voids, specialized metal pieces can be designed as part of a closure system, particularly for vented applications.

Preventing insects, birds & water intrusion

The open flutes or corrugated waves of metal panels, if left unsealed, create inviting entry points for various nuisances. Closure strips are the first line of defense:

• Insect and Pest Barrier: Small insects can build nests, and larger pests like rodents and birds can squeeze into these openings, making their way into your attic. Once inside, they can cause damage to insulation, wiring, and even create health hazards. Closure strips physically block these entry points.

• Water and Moisture Blockage: Wind-driven rain and melting snow can easily be forced up and into the unsealed voids of metal panels. This leads to leaks, moisture accumulation in the attic, potential mold growth, and accelerated deterioration of the roof deck and insulation. Closure strips create a snug seal that prevents this upward migration of water.

• Debris Prevention: Leaves, dust, dirt, and other windblown debris can accumulate in these open spaces, potentially clogging gutters or creating an environment for moisture retention and rot. Closure strips keep these areas clean and clear.

Where installation is critical (ridge, eave, gable)

Closure strips are strategically placed at specific termination points of the metal roof to ensure comprehensive protection.

• Eaves (Bottom Edge of Roof):

  • Purpose: Located under the metal panels at the lower edge of the roof (where panels meet the eave flashing or gutter).

  • Function: Prevents insects, wind, and water from blowing up into the roof structure from the bottom. "Inside" closure strips are typically used here, fitting the underside of the panel's profile.

• Ridge (Roof Peak):

  • Purpose: Placed under the ridge cap, where two roof slopes meet at the peak.

  • Function: Seals the void created by the panel profile as it meets the ridge cap, preventing rain, snow, and pests from entering the peak of the roof. "Outside" closure strips are commonly used here, fitting over the high ribs of the panel. Often, a "vented" closure strip is used at the ridge to allow for attic ventilation while still blocking pests and weather.

• Gable Ends (Side Edges of Roof):

  • Purpose: Installed along the sloped edges of the roof where the metal panels meet the gable trim or rake trim.

  • Function: Seals the open flutes along the side edges, preventing wind, rain, and pests from entering the roof system from the sides. This ensures a tight seal along the entire perimeter.

• Other Penetrations: While not always "strips," similar sealing concepts apply around chimneys, skylights, pipe vents, and other roof penetrations. Specialized flashings and sealants are used to ensure these areas are just as watertight and pest-proof as the main panels.

Compatibility with standing seam and corrugated panels

Closure strips are highly specialized and must be compatible with the specific profile of the metal roofing panels being installed.

• Corrugated and Ribbed Panels (Exposed Fastener Systems):

  • Compatibility: This is where closure strips are most visibly and critically used. Each manufacturer's corrugated or ribbed panel has a unique profile (the shape and spacing of its "waves" or ribs).

  • Fit: Closure strips are custom-cut or molded to precisely match the "positive" (high points) and "negative" (low points/flutes) contours of that specific panel profile. A perfect fit is essential for an effective seal. You need to ensure you purchase closure strips designed for your exact panel profile.

• Standing Seam Panels (Concealed Fastener Systems):

  • Compatibility: While standing seam roofs have a much smoother, flat appearance, closure strips are still often used. They are typically used at the eaves and ridges, particularly where the flat panel transitions into a folded edge or meets a trim piece, creating small gaps that still need to be sealed against insects and wind-driven rain.

  • Fit: For standing seam, the closure strips are often simpler "flat" strips that fit into the base of the seam or at the panel's end, rather than conforming to complex corrugations. Vented options are common at the ridge to facilitate airflow.

• Importance of Match: Using the wrong closure strip profile or a generic "universal" strip will result in an ineffective seal, defeating their purpose. Always use strips recommended or supplied by the panel manufacturer or a reputable roofing supplier that explicitly states compatibility.

Professional advice vs. DIY considerations

Installing closure strips, while seemingly simple, requires precision and knowledge.

• Professional Installation (Recommended):

  • Expertise: Professional roofers specializing in metal roofing understand the nuances of each panel profile and the critical locations for closure strip installation. They know how to cut, fit, and secure the strips to ensure a lasting, watertight, and pest-proof seal.

  • Precision: Correct alignment and secure fastening are vital. Professionals use the right adhesives and fasteners to ensure the strips stay in place for decades, even under thermal expansion and contraction.

  • Warranty Compliance: Proper installation of all components, including closure strips, is often a requirement to maintain the manufacturer's warranty on your metal roof system.

  • Safety: Roofing work involves inherent risks. Professionals have the necessary safety equipment and training.

• DIY Considerations (Proceed with Caution):

  • Cost Savings: The primary motivator for DIY is to save on labor costs.

  • Challenges:

    • Profile Matching: Accurately identifying and sourcing the correct closure strips for your specific metal panel can be challenging.

    • Cutting and Fitting: Precise cutting and fitting are essential, especially on complex rooflines or at angles. Improper cuts create gaps.

    • Adhesion and Fastening: Ensuring long-lasting adhesion and proper fastening requires understanding product specifications and environmental conditions.

    • Hidden Issues: A DIY installer might overlook subtle gaps or potential water ingress points that a professional would immediately identify.

  • Risk: An improperly installed closure strip can lead to leaks, pest infestations, or premature roof degradation, potentially voiding warranties and leading to costly repairs down the road.

While some highly experienced DIYers might manage, for the longevity and performance of a metal roof, professional installation of closure strips is highly recommended. The relatively small cost of professional installation of these critical components far outweighs the potential long-term damage and frustration of an improper DIY job.

Overall contribution to longevity and performance

Closure strips, despite their small size, are indispensable for the long-term longevity and optimal performance of a metal roofing system.

• Prevents Premature Degradation: By preventing water intrusion and pest infestation, closure strips protect the underlying roof deck, insulation, and structural components from moisture damage, rot, and contamination. This directly extends the life of the entire roofing system.

• Maintains Energy Efficiency: By sealing air gaps, they contribute to a more stable indoor temperature, reducing heating and cooling costs over the decades your metal roof is in service.

• Ensures Structural Integrity: By keeping out moisture, they prevent the weakening of wood decking or framing that could compromise the roof's structural integrity over time.

• Preserves Aesthetics: By preventing debris accumulation and maintaining a clean, sealed edge, they help preserve the attractive, sharp lines of your metal roof for its entire lifespan.

• Protects Investment: Given the significant investment in a metal roof, closure strips act as a low-cost insurance policy, protecting against common vulnerabilities that could otherwise lead to expensive repairs or premature replacement.

In summary, closure strips are not an optional accessory for metal roofing; they are a fundamental component. They ensure that the inherent durability and weather resistance of your metal panels are fully realized by sealing the vulnerabilities that would otherwise lead to leaks, pest problems, and diminished performance over the decades. For guaranteed peace of mind and maximum roof lifespan, ensure they are an integral part of your metal roof installation.

Unsure if your metal roof needs closure strips or if your current ones are performing optimally? Contact Masterpiece Roofing today for a professional inspection and expert advice on optimizing your metal roofing system's performance and longevity.