Tek screws with rubber washers combine a self-drilling metal screw with a sealing washer, making them useful for fastening roofing, siding, and other metal panels. The drill-shaped point can create its own hole in compatible materials, while the washer helps keep water out around the fastener. Choosing the right screw involves more than matching the panel color: material thickness, screw length, washer type, and exposure to weather all matter.
What Are Tek Screws With Rubber Washers?
“Tek screw” is a common U.S. trade name for a self-drilling screw. Its pointed tip has cutting flutes that drill through material as the screw advances, often eliminating the need to predrill a pilot hole when the fastener is rated for the job. Tek screws are commonly used to attach metal panels to metal framing, and some types are designed for fastening metal to wood.
A rubber washer is typically bonded to a metal washer beneath the screw head. When installed correctly, the rubber layer compresses against the panel and forms a seal around the hole. The metal portion spreads the clamping force over a wider area than the screw head alone. The elastomer is often EPDM, a weather-resistant synthetic rubber, though products vary and may use other materials.
These fasteners are also sold as self-drilling roofing screws, metal roofing screws, or screws with bonded sealing washers. “Tek” can refer to a particular product or be used generically, so buyers should check the package specifications rather than assume all self-drilling screws have the same drill-point capacity or washer construction.
Where They Are Used
Tek screws with sealing washers are most often used where a fastener penetrates an exterior metal panel and the opening needs protection from rain. Common applications include metal roofing, wall siding, agricultural buildings, sheds, carports, and metal-clad outbuildings. They may also be used on certain flashing or trim details when the manufacturer specifies a washered fastener.
The screw must suit both materials being joined. For example, a screw designed for thin sheet metal may not drill efficiently through a thick steel purlin. A fastener intended for wood framing may have a different thread design from one made for steel. The panel and supporting structure, not just the washer, determine the correct screw.
Installation location matters, too. Some roof systems require fasteners through the flat of the panel; others specify placement on a rib or a particular panel feature. The correct location depends on the panel profile and system design. Following the panel maker’s instructions helps preserve the roof’s water-shedding design and can reduce the risk of leaks or panel damage.
How the Sealing Washer Works
As the screw is tightened, the washer’s rubber face compresses between the metal washer and the panel. This compression helps close the path around the screw shank. The seal depends on proper contact, a sound panel surface, and a compatible washer—not simply on tightening the screw as hard as possible.
Too little compression can leave a gap that admits water. Too much can deform the rubber, distort the metal washer, damage the panel, or strip the screw’s threads. On a roof, a crushed or split washer can fail to seal even if the fastener feels tight. The goal is controlled compression consistent with the fastener or roofing manufacturer’s directions.
Rubber washers are not a substitute for sound roof design, properly overlapped panels, flashing, or underlayment. A washer can seal around an individual fastener, but it cannot correct a poorly detailed joint or a fastener placed where water collects.
Types and Specifications to Compare
Drill-point capacity
Self-drilling screws are available with different point styles and drilling capacities. A point suited to thin sheet metal may not be suitable for thicker structural steel. Product packaging or a technical data sheet should identify the approved material range, often expressed as a thickness range. The fastener’s drilling capacity is not the same as its ability to carry a structural load; those are separate considerations.
Screw length and thread
Length must provide adequate engagement in the supporting material while allowing the washer to seat against the panel. The needed length depends on the panel profile, any spacer or insulation, and whether the fastener enters wood or steel. Thread style also matters: many metal-to-metal screws use threads suited to steel, while metal-to-wood screws are designed to grip wood framing. Follow the system supplier’s selection guidance instead of choosing by appearance alone.
Washer material
EPDM washers are commonly selected for outdoor exposure because EPDM is used in weather-resistant sealing applications. Still, UV exposure, temperature, chemicals, and contact with other materials can affect service life. A washer’s suitability depends on the specific product and environment. Check the manufacturer’s data for compatibility and exposure limits, especially in coastal, industrial, or chemically demanding locations.
Coating and corrosion resistance
The screw’s coating should be appropriate for the environment and compatible with the roofing or siding material. Corrosion resistance can depend on the base metal, coating, washer assembly, and contact with dissimilar metals. Coastal air, industrial pollution, and persistent moisture can accelerate corrosion. In these settings, confirm that the fastener is approved for the exposure and panel material; a generic “coated” description is not enough to establish suitability.
Head style and color
Hex heads are common because they work with a nut driver and are easy to install with a drill or impact driver. Some products include painted heads to coordinate with roof or siding colors. Color matching is a finish choice, not proof that the screw has the correct structural rating, coating, or washer. Verify the technical specifications separately.
How to Choose the Right Fastener
Before buying, identify the panel material and thickness, the supporting structure, and the conditions where the fastener will be used. Then compare the screw’s drill-point capacity, length, thread, washer material, corrosion protection, and any system-specific approval. Roofing and siding manufacturers often publish installation guides that identify compatible fasteners and placement.
| Selection factor | What to check |
|---|---|
| Panel and substrate | Confirm whether the screw is intended for metal-to-metal or metal-to-wood fastening. |
| Thickness | Match the drill-point capacity to the combined material thickness specified by the product maker. |
| Length | Allow for the panel profile and required engagement in the supporting material. |
| Weather exposure | Check washer material and corrosion protection for the site conditions. |
| Roofing system | Follow the panel manufacturer’s requirements for screw type, location, and spacing. |
For a structural or code-regulated application, use fasteners specified by the project documents and applicable building requirements. A self-drilling tip makes installation easier; it does not automatically make a screw appropriate for structural connections, wind uplift, or every roofing assembly.
Installation: A Practical Checklist
- Read the product and panel instructions. Confirm the screw type, installation location, spacing, and tool guidance for the specific system. Requirements vary among panel profiles and substrates.
- Use the correct driver. A properly fitting hex nut driver reduces slipping and helps the installer control the screw. Use a drill or driver with adjustable speed and clutch settings where possible.
- Keep the screw aligned. Drive it perpendicular to the panel unless the manufacturer specifies another orientation. An angled fastener can seat unevenly and compromise the washer’s contact.
- Drive at a controlled speed. Let the drill point cut through the material instead of forcing the screw. Excessive speed or pressure can overheat the point, damage threads, or make it harder to stop at the correct compression.
- Stop when the washer seats correctly. The washer should contact the panel evenly and show the compression described by the manufacturer. Do not keep tightening after the rubber is visibly crushed or the panel begins to deform.
- Inspect the finished fastener. Check that the head is seated, the washer is intact and centered, and the panel is not visibly distorted. Replace fasteners with damaged washers or stripped threads rather than relying on a compromised seal.
Roof work also presents fall hazards. Use appropriate fall-protection practices and follow applicable workplace safety requirements. For extensive roofing, steep slopes, or work beyond a person’s experience, a qualified roofing contractor can help ensure safe and correct installation.
Common Installation Problems
Overtightening
Overtightening is one of the most common causes of washer failure. It can flatten or split the rubber, deform the metal washer, dimple the panel, or strip the connection. If the washer is damaged, the fastener should generally be replaced according to the system manufacturer’s repair guidance.
Undertightening or uneven seating
A screw that is not seated firmly may leave a gap beneath the washer. A screw driven at an angle can also compress one side more than the other. Check the fastener’s alignment and seating during installation rather than assuming that the drill’s sound or resistance confirms a watertight seal.
Wrong screw for the substrate
A screw with insufficient drilling capacity may spin, overheat, or fail to penetrate the supporting metal correctly. A thread designed for steel may not provide the intended hold in wood, and a wood-thread screw may not be appropriate for steel framing. Match the fastener to the materials and thicknesses listed by its manufacturer.
Incorrect placement or spacing
Fasteners placed in the wrong part of a panel or spaced differently from the specified pattern can affect weather resistance and performance. The correct pattern depends on the roof system, panel design, support spacing, and project requirements. Avoid applying a spacing rule from a different panel or roof assembly.
Reusing or mixing fasteners
Removed screws may have damaged threads or washers and may not provide a reliable seal when reinstalled. Mixing fastener types, washer materials, or coatings can also create inconsistent performance or compatibility concerns. Use the specified product and replace suspect fasteners with approved equivalents.
Maintenance and Replacement
Periodic visual checks can help identify loose, missing, corroded, or visibly damaged fasteners. Pay attention to cracked or deteriorated washers, rust staining, and signs of water entry inside the building. Inspection frequency should reflect the building’s exposure and the roofing system’s maintenance instructions.
A leaking roof does not always have a failed screw washer as its cause. Water can enter at panel laps, valleys, flashing, penetrations, or damaged panels and travel before appearing indoors. Finding the source may require examining the full roof assembly. Repairs should use compatible materials and follow the panel manufacturer’s instructions; sealing every screw with caulk is not a reliable substitute for correcting the underlying issue.
Finding Reliable Product Information
Product data sheets are the best place to verify a screw’s drilling range, dimensions, washer material, coating, and intended applications. Roof-panel manufacturers’ installation manuals provide system-specific requirements, including fastener location and spacing. For general guidance on metal roofing and building-envelope details, resources such as the Metal Construction Association can provide industry context, while the screw manufacturer remains the authority for its product’s specifications.
When a project involves structural loads, unusual exposure, or a roof assembly with warranty requirements, the installer should consult the building designer, panel supplier, or qualified contractor. The right Tek screw is the one approved for the specific panel, support, and exposure—not simply the one that fits the driver.