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MoistureLok Anti-Condensation Membrane
Factory-applied condensation control that installs with the panel and saves labor.
What is MoistureLok?
MoistureLok is an engineered anti-condensation membrane that absorbs moisture when dew-point conditions occur and releases it back into the air as temperatures normalize. It forms small pockets beneath the panel substrate to manage condensation before it drips inside the building.
MoistureLok is a factory-applied anti-condensation membrane that traps and stores moisture beneath metal roofing panels, preventing drip and protecting the building interior. Because the membrane is applied during panel production, it installs with the roof panel rather than as a separate field-installed layer—saving labor, reducing jobsite steps, and eliminating the need to inventory or handle traditional vapor barriers. MoistureLok is ideal for projects where condensation control, faster installation, and long-term durability are priorities.
MoistureLok Ideal Applications
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Buildings with elevated interior humidity levels.
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Structures experiencing cold-to-warm temperature transitions.
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Applications where condensation control beneath metal panels is critical.
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Warehouses, gymnasiums, and manufacturing facilities with moisture-generating operations.
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Agricultural buildings with high internal moisture loads.
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Wall and roof assemblies prone to dew-point-related condensation.
MoistureLok Top 3 Benefits
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Installs with the Panel for Significant Labor Savings: Because MoistureLok is factory-applied, it installs at the same time as the metal roof panel, eliminating the need for separate vapor barrier materials, handling, and field installation steps.
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Reduces Material and Project Costs: By removing the need for traditional vapor barrier products, tapes, and fasteners—as well as the labor to install them—MoistureLok lowers overall project costs and simplifies jobsite logistics.
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Low-Maintenance, Long-Term Condensation Protection: MoistureLok is engineered to absorb and release condensation automatically with minimal maintenance. The membrane resists bacteria, can be cleaned with a hose or pressure washer, and has demonstrated long-term durability with no degradation found in accelerated aging tests.
MoistureLok Details
MoistureLok is a factory-applied anti-condensation membrane that installs with the panel and removes the need for separate vapor barrier materials or field installation. The membrane has more than 20 years of proven performance with no identified degradation and can hold roughly one quart of moisture per 10 square feet. For lap applications, the bottom two to three inches of the overlapping panels and trim should be heat-treated, or “glazed,” to fuse the fibers and prevent capillary wicking. Once bonded, MoistureLok is highly resistant to removal, can be cleaned with a hose or pressure washer, and carries a UL 723 classification. Availability varies by facility and may require additional lead time.
MoistureLok is available on these panels
*MoistureLok is not available at all McElroy Metal facilities. Extra lead times may apply.
MoistureLok is available on these panels
*MoistureLok is not available at all McElroy Metal facilities. Extra lead times may apply.
MasterLok-90 (also referred to as ML-90) is a snap together trapezoidal standing seam system and MasterLok-FS is a mechanically seamed trapezoidal system. Both are designed for projects with slopes as low as 1/4:12.
MasterLok-FS (also referred to as ML-FS) is a mechanically seamed trapezoidal standing seam system also designed for projects with slopes as low as 1/4:12.
McElroy’s R-Panel features a 1 1/4" major rib, 12 inches on center. With a bold profile, R-Panel is commonly utilized for residential roofing, primarily in the Southwestern region of the US. An optional Purlin Bearing Leg (PBR) rests on substructural framing or roof deck to provide support for fastening the panel lap.
Max-Rib is a low profile (3/4") panel that is very popular with homeowners across the country due to its aesthetic appeal and price point. This panel profile is also very common in the industry and many manufacturers offer this panel in a wide variety of steel substrates and coatings. Homeowners should make sure the product being installed on their home matches their long-term performance criteria. For residential applications, McElroy strongly recommends a Galvalume steel substrate with Kynar 500® (PVDF) coatings, which offer optimal performance and protection against fade and chalk.
Multi-Rib is McElroy’s proprietary version of the industry’s standard R-Panel and commonly utilized for residential roofing, primarily in the Southwestern region. Featuring 1 1/4" major ribs, 12 inches on center, Multi-Rib's bold profile adds a distinct beauty to any home. An optional Purlin Bearing Leg (PBR) rests on substructural framing or roof deck to provide support for fastening the panel lap.
Mesa is a low profile (3/4") panel that is similar in appearance to Max-Rib. However, Mesa is both patent and copyright protected, which means it can't be copied by manufacturers offering lower quality steel substrates and coatings. Mesa is a great choice for homeowners that want quality assurance and a distinct appearance that can't be copied.
MasterLok-90 (also referred to as ML-90) is a snap together trapezoidal standing seam system and MasterLok-FS is a mechanically seamed trapezoidal system. Both are designed for projects with slopes as low as 1/4:12.
MasterLok-FS (also referred to as ML-FS) is a mechanically seamed trapezoidal standing seam system also designed for projects with slopes as low as 1/4:12.
McElroy’s R-Panel features a 1 1/4" major rib, 12 inches on center. With a bold profile, R-Panel is commonly utilized for residential roofing, primarily in the Southwestern region of the US. An optional Purlin Bearing Leg (PBR) rests on substructural framing or roof deck to provide support for fastening the panel lap.
Max-Rib is a low profile (3/4") panel that is very popular with homeowners across the country due to its aesthetic appeal and price point. This panel profile is also very common in the industry and many manufacturers offer this panel in a wide variety of steel substrates and coatings. Homeowners should make sure the product being installed on their home matches their long-term performance criteria. For residential applications, McElroy strongly recommends a Galvalume steel substrate with Kynar 500® (PVDF) coatings, which offer optimal performance and protection against fade and chalk.
Multi-Rib is McElroy’s proprietary version of the industry’s standard R-Panel and commonly utilized for residential roofing, primarily in the Southwestern region. Featuring 1 1/4" major ribs, 12 inches on center, Multi-Rib's bold profile adds a distinct beauty to any home. An optional Purlin Bearing Leg (PBR) rests on substructural framing or roof deck to provide support for fastening the panel lap.
Mesa is a low profile (3/4") panel that is similar in appearance to Max-Rib. However, Mesa is both patent and copyright protected, which means it can't be copied by manufacturers offering lower quality steel substrates and coatings. Mesa is a great choice for homeowners that want quality assurance and a distinct appearance that can't be copied.
Find a Distributor / Contractor Near You
Whether you’re building a new home or planning renovations, a metal roof can deliver long-term cost savings and comfort. To explore your options and find the product that meets your aesthetic and budgetary needs, contact a McElroy Metal distributor or contractor in your area today. We can’t wait to help make your dream home a reality.
Frequently Asked Questions
The questions below address common considerations and help guide product selection for your project.
Why Choose McElroy Metal
McElroy Metal is an employee-owned manufacturer with more than six decades of experience producing high-quality metal roofing, wall systems, and substructural components. Our nationwide manufacturing and service center network ensures consistent availability, responsive support, and dependable delivery. Built on a culture of craftsmanship and partnership, our products are engineered for long-term durability and trusted performance on projects of every size.