For a small leak around an existing exposed metal-roof screw, Loctite recommends PL Roof and Flashing, a polyurethane sealant. It is a repair option—not a universal roof-installation specification. Check the screw and sealing washer first: a loose, damaged, or incorrectly installed fastener may need correction or replacement, not a bead of caulk.
Start by checking the screw and washer
Exposed-fastener metal roofing relies on properly installed roofing screws and sealing washers to close penetrations. Metal Roof Source says its correctly installed fasteners with sealing washers should effectively seal the holes; its manual covers its own products and a typical roof, so project-specific requirements may differ. See its installation manual.
Before applying anything, inspect the fastener, washer, surrounding coating, and panel. Look for movement, corrosion, damage, or an enlarged hole. Sealant may not correct a compromised fastener or damaged roof material; consult the roof-system maker’s current repair instructions.
Choose sealant for the leak location and exposure
Small leak around an exposed screw
Loctite’s product guidance recommends PL Roof and Flashing for small leaks around screws, flashing, and seams. The manufacturer describes it as UV resistant, paintable, and weatherproof. Those are product claims, not proof of compatibility with every metal, finish, or roof warranty. Check the current label and roof-system instructions before use: Loctite PL Roof and Flashing product information.
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- POLY SEALANT – Geocel 4500 Roof Bonding Sealant is a premium Scypolymer one-component, proprietary bonding sealant specifically designed for roofing applications and systems. It applies, adheres, and cures underwater.
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- IDEAL FOR – This durable sealant is ideal for use on asphalt shingles, steel, concrete, EPDM, primed TPO, primed PVC, Hypalon (black only), metal, wood, and other common building substrates.
- EASY TO USE – No additional adhesives or sealants are needed when you use this flexible sealant. It has a non-flammable formulation and works with EPDM membranes, tapes, and patches. It can also be used as a night seal and for core/test cuts.
- GEOCEL – Founded in 1974, the Geocel brand provides innovative, specially designed sealants. Quality is a key ingredient in every Geocel product and service offered, which is why professionals have come to trust and depend on Geocel products.
Panel laps and concealed seams
Butyl tape or a specified tube sealant may be suitable where the roof design calls for it to be compressed inside a concealed joint. Follow the panel maker’s directions for sealant type, tape dimensions, bead size, and placement. Do not leave butyl tape exposed unless that particular product’s instructions allow it. The New Zealand Metal Roofing Manufacturers Inc. (NZMRM) Code of Practice explains the principle: “In most cases, the post application of sealant to the outside of a joint is both futile and unacceptable.” This is general industry guidance from New Zealand, not approval for a particular roof system. See its Sealants guidance.
Metal-roof fastener caps
Fastener caps are a distinct repair system, not interchangeable with a generic surface dab. Henry says its Butyl Caps and seam tape should not be left exposed and must be top-coated with AcryShield. Follow the product’s specified coating system and application details: Henry roofing coatings information.
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- Seals leaks in all weather
- Extended outdoor durability
- Prevents ice/water damage
- Waterproof bond
- 10. 3-ounce cartridge; Coverage: 30 linear feet using a 1/4-inch bead; Specifications: ASTM D-4586, Fed. Spec. SS-C-153 Type I
Silicone and other chemistries
The NZMRM Code says metal-roof sealants are generally neutral-cure silicone or modified silicone and warns against acid-cure silicone. That general statement does not establish that either type is suitable for every screw repair, metal, or coating. Use only a sealant approved for the actual roof materials and application.
How to decide what repair is appropriate
- Identify the roof system. Find the panel and fastener information, then check the manufacturer’s current installation or repair instructions and any project-specific requirements.
- Inspect the leak area. Check the screw, washer, metal, and coating for looseness, corrosion, damage, or an enlarged hole. If the fastener or panel is compromised, determine the required repair or replacement rather than assuming caulk will fix it.
- For a small exposed screw-area leak, use a metal-roof sealant approved for the roof and permitted by its manufacturer. Loctite names PL Roof and Flashing for small leaks around screws. Follow the current label for surface preparation, application conditions, and cure.
- For a lap or seam leak, use the sealant type and bead or tape placement specified for that panel profile. These materials are commonly designed to work compressed within a joint, not as an exposed coating over it.
- Escalate extensive damage. Loctite advises replacing a panel when flashing damage is extensive and following the roof maker’s joint-preparation directions. See its guide to sealing a metal roof.
Prepare and apply it without creating a new path for water
For the applications covered by its Code, NZMRM calls for clean, dry surfaces and a continuous bead without gaps. It also cautions that a complete ring of sealant around a fastener can trap air and form a channel when compressed. Do not assume that encircling the screw is the right method; use the roof-system and sealant instructions for placement.
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- Adheres to Kynar coated metals
- Applies easily in extreme weather conditions
- Excellent adhesion to most common building materials
- UV-resistant
- VOC-compliant
For concealed joints, the Metal Construction Association’s Roof Seaming Best Practices Guide advises confirming with the supplier that the sealant is intended for metal roofing and matching the tape or bead specification to the seam. MCA describes its technical resources as general seaming practice to use alongside material installation guides and project drawings; its resource page identifies the guide as published in August 2015.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.What “best” means for this repair
There is no single sealant chemistry established as best for every metal-roof screw. The right choice depends on the roof material and coating, whether the sealant will be exposed or compressed inside a joint, the manufacturer’s approved details and warranty requirements, and whether the source of the leak is actually a screw, seam, or damaged panel. For a small exposed screw-area leak, PL Roof and Flashing is a named manufacturer-recommended option; for installation and concealed joints, the roof-system specification takes priority.
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- Ames Maximum-Stretch is a white, elastomeric, acrylic, rubberized roof coating & sealant with 650% elongation to resist cracking & peeling. With 88% light reflectivity, the bright white finish reduces surface temperatures resulting in lowered cooling costs.
- Ames Maximum-Stretch adheres to metal roofing, tar, rolled roofs and more. Use as a RV roof sealant, waterproof sealant, rubber roofing material and more. Designed for low-slope roof maintenance.
- 650% elongation - does not flake, chip or peel - elastomeric and rubberized coating and sealant. Rubber roofing material is 88% light reflective resulting in lowered cooling costs. Brush, roll or spray on!
- Non-toxic, eco-friendly, low VOC & made in the USA
- 1 Gallon - Our waterproof roof sealant is packaged in 1 gallon Pail. Designed for low-slope roof maintenance on metal roofing, built-up roofing, rolled roofing and more.
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- INDUSTRIAL STRENGTH BITUMEN FORMULA - Create a seamless waterproof membrane on flat roofs, metal roofs, low slope roofs, foundations, gutters, concrete surfaces, planter boxes, and more. Our premium liquid rubber forms a durable barrier against water infiltration where other sealants fail. Superior alternative to traditional roof tar or patch products
- SUPERIOR FLEXIBILITY & DURABILITY - With over 950% elongation, this waterproof sealant maintains adhesion even with building movement and temperature changes. Our sealant is designed to resist cracking, peeling, and UV damage. Creates a flexible rubberized coating that delivers long-lasting protection
- PROFESSIONAL COVERAGE SPECIFICATIONS - Brush, roll or spray on - For flat/low slope roofs & standing water surfaces: 1 gallon covers 15 sq ft (3-4 heavy coats to achieve 60-80 mil membrane). For vertical surfaces like foundations: 1 gallon covers 30 sq ft (2-3 heavy coats for 30 mil membrane). Ideal for both roof repair and preventative maintenance applications - Goes on brown and dries BLACK
- WATER-BASED ADVANCED FORMULA - Unlike harsh roof tar or solvent-based products, our water-based formula contains no VOCs or harmful odors, making it perfect for indoor and outdoor use. Doesn't damage foam insulation or sensitive materials. Perfect for waterproofing projects in confined spaces
- ENGINEERED WATERPROOFING SYSTEM - For maximum protection, use with Liquid Rubber Seam Tape or Geo-Textile to bridge joints, seams, vents, skylights, and protrusions where movement may occur. Creates a comprehensive waterproofing system for long-lasting leak repair and prevention on your roof, basement, or foundation
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