Metal-to-Wood vs Metal-to-Metal Roofing Screws: Which Do You Need?

Key Takeaways

• Start with one non-negotiable question: Is your substrate wood or metal? That single choice dictates the screw family, drill point, thread style, and whether the roof stays watertight for decades or starts leaking in a couple of seasons.
• Metal-to-wood roofing screws use a Type 17 self-piercing point and a coarse thread that grips wood. They’re ideal for plywood, oriented strand board (OSB), and dimensional lumber, but they won’t drill into steel purlins.
• Metal-to-metal roofing screws rely on Tek self-drilling points and fine threads that cut and form threads in steel. They’re built for purlins, Z-channels, and I-beams, and they don’t hold in wood.
• Tek point selection makes or breaks the install. Tek #1 and #2 handle light-gauge sheet-to-sheet, Tek #3 is the everyday purlin choice, and Tek #4 and #5 are for heavy structural steel. Pick incorrectly, and you’ll snap screws or strip holes.
• Ethylene propylene diene monomer (EPDM) washers outlast neoprene, especially in hot-sun and coastal zones. Over-tightening crushes any washer and invites leaks, so snug is the rule.
• Stainless steel (304 inland, 316 near saltwater) costs more up front but can last the life of the roof in corrosive environments. Bi-metal screws pair a carbon steel drill tip with a stainless body for a smart middle ground.
• Details are crucial at install: drive straight, place screws in the flats (not on rib crowns), limit drill speed to 2,500 RPM or less, and skip the impact driver that snaps heads and walks points.
• Expect spacing around 24″ on center in field zones, 12″ at eaves and ridge, and down to 6″ in corners/high-wind zones. Verify with American Society of Civil Engineers 7 (ASCE 7) wind load guidance or your local authority.
• Supply Maverick carries the hard-to-find sizes such as long Tek #4/#5 “beambusters,” oversize #14 FastGrip replacements for wallowed-out holes, and painted screws that match our metal panels, all with same-day shipping on most orders placed before 12 p.m. EST.
• Callbacks are expensive. Spending an extra $0.10 per screw now beats $500 to $2,000 in return trips later and helps avoid $10,000+ interior damage from leaks.

Understanding Your Substrate: The First Decision

Everything else flows from this decision. Before you compare points, threads, or pricing, identify what sits beneath your metal panel. Whether you’re fastening into plywood, OSB, dimensional lumber, or steel framing, the substrate determines which screw can develop dependable holding power.

Why Your Substrate Is the Most Important Part

Every component of a roofing screw — point, threads, diameter, and washer — works as a system designed for a specific base material. Wood depends on coarse, deep threads that lock by friction and fiber compression. Steel needs a self-drilling point that bores cleanly, followed by fine threads that form mates in the steel. Swap those roles, and you’ll either fight to seat the screw or end up with a weak connection that won’t last.

Pros who begin by asking “What’s my substrate?” avoid most fastener headaches. Wood deck? Choose Type 17, metal-to-wood screws. Steel purlin? Go with metal-to-metal, Tek-point screws sized for your gauge. Mixed conditions (retrofits, repairs)? Match each fastener to both the entry material and the base material you’re anchoring into.

Wood Substrates (Plywood, OSB, Dimensional Lumber)

Wood sheathing and framing (think 1/2″ to 3/4″ plywood or OSB and 2x lumber) behave very differently than steel. Holding power depends on penetration depth, species, density, and moisture content. Coarse-thread screws with Type 17 tips pierce the panel skin, then displace wood fibers as threads advance, creating a reliable friction lock.

• Best screw type: Metal-to-wood roofing screws with Type 17 self-piercing points and coarse threads (often about 10 to 14 threads per inch).
• Penetration target: Aim for 1″ of embedment into solid wood when possible; 1/2″ is an absolute minimum if thickness is limited.
• Placement: In the flat of the panel where it bears on the deck or purlin, not on the rib.
• Chemistry caution: For pressure-treated lumber, confirm the screw’s coating or a stainless option is compatible with the wood preservatives.

Field tip for anyone installing in high-moisture regions or unconditioned agricultural buildings: seasonal wood movement can loosen marginal fasteners. Moving up to a #12 diameter and ensuring full embedment helps prevent back-out.

Metal Substrates (Purlins, Z-Channels, I-Beams)

Steel framing demands a screw that drills and taps in one pass. Tek-point screws do both. The tip cuts a clean hole through the panel and steel, and the fine threads form as the screw advances. Choose the Tek point by the total steel thickness you’ll penetrate. Too small and you stall or snap the head; too large and you hog out the hole and lose thread engagement.

• Best screw type: Metal-to-metal roofing screws with Tek self-drilling points and fine threads (typically 18 to 24 threads per inch).
• Thickness-driven selection: Tek #1 to #2 for thin sheet-to-sheet, Tek #3 for common commercial purlins, Tek #4 to #5 for heavy structural members.
• Head seating: The washer must bear on a flat portion of the panel; never set a sealing washer on a rib crest.

Metal-to-Wood Roofing Screws: Complete Guide

A metal-to-wood screw has one job: pierce the panel, then grip solid lumber securely. This section shows you what to look for before you order or start fastening, including the Type 17 point, coarse thread, length, washer, and finish that fit wood-backed applications.

What Are Metal-to-Wood Screws?

Metal-to-wood roofing screws are self-piercing fasteners with sharp Type 17 points and coarse, deep-cut threads made to lock into wood. They pierce 20- to 29-gauge metal panels easily, then bite into plywood, OSB, or dimensional lumber. They aren’t self-drilling in steel and aren’t suitable for metal substructures.

Key Characteristics of Metal-to-Wood Screws

• Type 17 self-piercing point: Starts fast, reduces panel deformation, and usually eliminates the need for pre-drilling.
• Coarse thread pitch (about 10 to 14 threads per inch): Maximizes bite and pull-out resistance in wood fibers.
• Common diameters: #9, #10, and #12; larger diameters increase shank strength and thread bearing area.
• Typical lengths: 1″ to 2.5″, measured from the underside of the head; select for total stack-up and target embedment.
• Sealing washers: Ethylene propylene diene monomer (EPDM)-bonded washers create a durable weather seal when properly compressed.
• Head styles: A 1/4″ hex head is the field favorite for positive driver engagement and speed; painted heads are available to match panel finishes.
• Coatings: Exterior-rated coatings or stainless options improve corrosion resistance, especially with treated lumber or aggressive environments.

When to Use Metal-to-Wood Screws

• New residential roofs over plywood or OSB decks.
• Agricultural buildings and pole barns fastening into wood purlins or girts.
• Furring-strip retrofits where panels land on dimensional lumber.
• Trims and flashings fastened to wood blocking.

If the anchor material is wood, metal-to-wood screws are the right call. They pierce the panel skin cleanly and achieve reliable holding by engaging wood fibers. If your base is steel (of any thickness), switch to a metal-to-metal screw.

Fastener Specifications and Pull-Out Values

Pull-out capacity in wood isn’t a fixed value. It varies by species and grade, fiber orientation, density, moisture, and the amount of thread you embed. 

• Diameter: In identical wood, a #12 provides more holding power than a #10 thanks to greater thread circumference and shank strength.
• Length: Choose a length that achieves at least 1″ of thread embedment into solid wood whenever possible (or a minimum of 1/2″ if thickness is constrained).
• Threads engaged: More engaged threads generally help, but avoid bottoming into voids or over-penetrating thin substrates.

Because capacities vary by species and grade, consult the screw manufacturer’s technical data for tested values in comparable wood. On marginal substrates, such as weathered lumber, low-density OSB, or old nail lines, consider a larger diameter (e.g., #12), a longer length, or additional fasteners per the panel manufacturer’s guidance.

Installation Best Practices for Metal-to-Wood Screws

• Use a variable-speed drill at 2,500 RPM or less; too much speed overheats tips and burns off coatings.
• Avoid impact drivers; they’re prone to snapping heads, walking the tip on sloped panels, and over-compressing washers.
• Drive perpendicular to the panel; angled screws distort washers and leave gaps.
• Seat washers snug so the EPDM compresses slightly without mushrooming.
• Fasten through the flats where the panel bears on the substrate, not in the ribs.
• Target at least 1″ of embedment into solid wood; verify length against your total stack-up.
• Brush off metal shavings (swarf); hot filings left on painted panels can stain and rust.

Common Mistakes and How to Avoid Them

• Using metal-to-wood screws on steel purlins: Type 17 points won’t drill steel, so expect broken tips, scuffed paint, and wasted time.
• Over-tightening: Crushed washers lose their elasticity and leak later; set them snug, not smashed.
• Under-tightening: A loose washer can’t seal; look for slight, uniform compression.
• Driving at an angle: Even a small tilt leaves a crescent gap under the washer.
• Too-short screws: Less than 1/2″ embedment risks pull-out; choose a longer length or a larger diameter.
• Ignoring treated wood chemistry: Pick compatible coatings or stainless where preservatives are aggressive.

Metal-to-Metal Roofing Screws: Complete Guide

Steel needs a screw that drills cleanly and forms dependable threads in the substrate. Here’s how to choose the right Tek-point fastener for the steel you’re working with, whether you’re attaching panels to purlins, fastening trims, or working through heavier structural members.

What Are Metal-to-Metal Screws?

Metal-to-metal roofing screws are self-drilling fasteners with Tek points that bore through steel, then form threads as they advance. They use fine thread pitches to maximize engagement in metal. They’re indispensable for attaching panels or trims to steel purlins, Zs, channels, or I-beams. They aren’t designed for wood and won’t hold in it.

Key Characteristics of Metal-to-Metal Screws

• Tek self-drilling points: The point number corresponds to total steel thickness capacity.
• Fine thread pitch (typically 18 to 24 threads per inch): Creates more contact points in thin steel for stronger engagement.
• Common diameters: #12 and #14 for structural panel attachment; smaller sizes for stitch and lap screws.
• Length options: From 3/4″ up to 16″, depending on stack-up and structural thickness.
• Sealing washers: EPDM-bonded washers for weather-exposed fastenings; non-washered options for concealed applications and lap stitching with sealant tape.
• Coatings and alloys: Exterior-grade-coated carbon steel, plus stainless or bimetallic options for corrosive environments.
• Painted head choices: Match your panel color for a clean, professional finish.

Understanding Tek Point Ratings (This Is Critical)

Tek point numbers reflect the drill tip’s capacity. Match the number to the combined thickness of all steel you’re drilling through (panel plus purlin or web). A quick field guide:

• Tek #1: Very light-gauge sheet-to-sheet (around 22 gauge and thinner). Drill point about 0.016″ to 0.031″; max combined thickness roughly 0.035″ to 0.060″.
• Tek #2: Light to medium gauges (roughly 18 to 14 gauge). Drill point about 0.050″ to 0.070″; max thickness around 0.060″ to 0.090″.
• Tek #3: The commercial standard for typical purlins (about 18 to 12 gauge, 0.090″ to 0.190″ total). Drill point about 0.115″ to 0.130″.
• Tek #4: Heavy structural members (roughly 7 to 3 gauge, 0.190″ to 0.250″). Drill point about 0.190″ to 0.200″.
• Tek #5: Maximum penetration, up to about 1/2″ thick steel. Drill point about 0.250″ to 0.315″; often called the “beambuster.”

If screws snap, tips burn, or holes strip, odds are the Tek point didn’t match the thickness. Right-size the Tek, and you’ll move through purlins without drama.

When to Use Metal-to-Metal Screws

• Attaching metal roofing or siding panels to steel purlins or girts.
• Fastening to Z-channels, C-channels, struts, and I-beams.
• Lap and stitch screws for panel-to-panel seams (thin sheet-to-sheet work typically uses Tek #1 to #2).
• Clip fastening for standing seam systems to steel sub-framing (follow the clip manufacturer’s specs).
• Retrofits where new metal layers tie into existing steel framing.

Fastener Specifications and Holding Power

In steel, performance is about the threads you form and how the panel bears under the head and washer. Thin sheet risks pull-over if the washer bears on a soft rib, while thicker members require the correct Tek so the drill point penetrates cleanly.

• Diameter is key: A #14 often increases thread engagement and the head/washer bearing area compared to a #12.
• Length selection: Long enough to penetrate the steel member fully and develop full thread formation, but not so long that interior components snag.
• Washer fit: EPDM washers need a flat bearing surface on the panel to seal properly.

For engineered assemblies, verify pull-out, pull-over, and shear values from the fastener manufacturer, and ensure they align with your design loads and panel supplier’s approvals.

Installation Best Practices for Metal-to-Metal Screws

• Speed control: Keep the drill at 2,500 RPM or less; high RPM overheats tips and damages coatings.
• Right tool: A drill gives steady torque; impact drivers tend to over-tighten, walk the point, or snap screws.
• Keep it straight: Drive perpendicular for even thread formation and a reliable washer seal.
• Support and clamp: Prevent panel creep and point walking; let the Tek do the drilling and don’t force it.
• Chip management: Clear swarf so hot filings don’t mar painted finishes.
• Stainless exception: In thick steel, a small pilot can reduce galling for stainless or bi-metal screws; always follow the manufacturer’s guidance.

Common Mistakes and How to Avoid Them

• Wrong Tek number: Undersized points stall and snap; oversized points strip threads in thin steel.
• Setting in ribs: Washers don’t seal reliably on rib crowns; fasten in the flats where the panel bears on the purlin.
• Over-driving: Spins out threads in thin-gauge steel; you’ll get a spinner that never tightens.
• Under-driving: Washers don’t seal; water finds the gap.
• Using metal-to-metal screws in wood: Tek tips auger out wood fibers, and fasteners loosen over time.

Head-to-Head Comparison: Metal-to-Wood vs Metal-to-Metal

Both screw families attach metal panels, but their points, threads, and holding mechanics serve different substrates. This side-by-side view makes the differences easy to spot so you can compare installation speed, cost, availability, durability, and the type of grip each screw provides.

Drill Point Technology

Metal-to-wood screws use a sharp Type 17 tip that pierces the cladding and parts wood fibers. Metal-to-metal screws use Tek points that cut a hole in steel before threads form. One relies on piercing and displacement; the other relies on drilling and thread formation. That’s why Type 17s can’t drill steel, and why Tek tips over-drill and ruin holding in wood.

Thread Design and Grip Mechanics

Coarse threads on wood screws wedge deep into fibers to resist pull-out. Fine threads on metal screws maximize contact within thin steel walls, forming stronger threads. Swap those designs onto the wrong substrate, and you’ll guarantee weak connections and premature failure.

Size and Availability

Metal-to-wood screws commonly run #9 to #12 in diameter and 1″ to 2.5″ in length for roofing and siding. Metal-to-metal screws are typically #12 to #14, with lengths from 3/4″ for lap screws up to 16″ for deep structural fastening. Supply Maverick stocks both families in a wide range of sizes and head colors, including hard-to-find long Tek #4 and #5 options for structural steel and oversize #14 replacement screws for damaged holes.

Cost Comparison

Expect metal-to-wood roofing screws to land around $0.06 to $0.12 each depending on size and coating. Metal-to-metal roofing screws generally run $0.10 to $0.26 each based on diameter, Tek point, and finish. Stainless options can be two to three times the cost of galvanized, but in coastal applications, they may eliminate the need for future replacement cycles. Spending an extra dime per screw today beats paying $500 to $2,000 in callbacks later.

Installation Time and Labor

Match screw to substrate and both types install quickly. Wood screws pierce and bite with light pressure; Tek screws drill and tap efficiently when the point rating suits the steel thickness. Use the wrong type, and you’ll waste time snapping screws, wallowing holes, and fighting under- or over-driven washers. Picking correctly pays for itself in labor saved on day one.

Performance and Longevity

With proper installation, high-quality fasteners often deliver 20 to 40 years of service. Service life depends on washer material (EPDM outlasts neoprene two to three times under UV), corrosion resistance (coatings versus stainless or bimetal), and technique (straight, snug, and properly spaced). Put the wrong screw in the wrong substrate, and it won’t last, period.

Decision Framework: How to Choose the Right Screw

Use this quick process before you place an order. A few checks up front can save you from stripped holes, failed seals, and a frustrating rework later. Narrow your choice by checking the substrate, panel system, environment, building requirements, and fastener specifications.

Step 1: Identify Your Substrate

1. Confirm what you’re anchoring into, be it wood (plywood or OSB, dimensional lumber) or steel (purlins, Zs, I-beams).
2. If it’s steel, estimate the total thickness you’ll drill through (panel plus structural member) to choose a Tek rating.
3. If it’s wood, verify you’ve got enough thickness for at least 1/2″ embedment, ideally 1″.
4. Note any pressure-treated lumber and select compatible coatings or stainless if needed.

Step 2: Determine Your Panel System

1. For exposed-fastener panels (corrugated, 5V, R-panel), fasten through the flats with washered screws matched to the substrate.
2. For standing seam systems, follow the clip manufacturer’s fastener requirements; the wood or steel substrate still determines the screw family.
3. For lap joints and trims, plan for smaller stitch or lap screws (Tek #1 to #2 for sheet-to-sheet) and use sealant tape where specified.

Step 3: Consider Environmental Factors

1. Sun exposure and heat cycling favor EPDM washers over neoprene; EPDM lasts significantly longer under UV exposure.
2. Inland corrosion protection: High-quality coated carbon steel or 304 stainless generally works well.
3. Coastal or chloride-rich areas: 316 stainless is the go-to within about 3 miles of saltwater; bi-metal screws deliver stainless bodies with a carbon steel drill tip.
4. Snow and ice zones: If adding snow guards (such as Snow Defender devices), match fastener material to roof conditions and the manufacturer’s recommendations.

Step 4: Verify Building Code Compliance

1. Use ASCE 7 wind zone maps and roof zone definitions (corner, perimeter, field) to set spacing. Typically 24″ on center in the field, 12″ at eaves and ridge, and as tight as 6″ at corners in high-wind areas.
2. Check your panel manufacturer’s installation manual and approvals; warranties often hinge on correct fasteners and spacing.
3. For engineered projects, ensure fastener capacities meet design loads and local code requirements.

Step 5: Select Size and Specifications

1. Pick the family: Type 17 metal-to-wood or Tek metal-to-metal based on the substrate.
2. Choose diameter: #10 for standard wood applications, #12 for extra bite, #14 for oversized repairs or heavy-duty steel.
3. Choose length: Account for panel thickness, any insulation or underlayment, and the target embedment (wood) or full thread formation (steel).
4. Choose Tek rating (metal): Match to the total steel thickness, which is #3 for most purlins, #4 and #5 for heavy members, #1 and #2 for stitch or lap.
5. Choose washer: EPDM for longevity; painted washers and heads for a clean look on exposed fasteners.
6. Choose finish or alloy: Coated carbon steel for inland; 304 or 316 stainless, or bimetal, for corrosive environments.

Real-World Application Scenarios

Every roof has its own substrate, exposure, and fastening pattern. These examples show how the selection process works on the jobs contractors and DIYers run into most often, from residential roofs over wood decks to commercial buildings on steel purlins and repairs in corrosive environments.

Scenario 1: Residential Metal Roof on a Wood Deck

You’re installing a new 29-gauge corrugated panel over 5/8″ OSB sheathing on a home. The substrate is wood, so you’ll choose a Type 17 metal-to-wood roofing screw. A #10 diameter is common for residential work, while a #12 offers more grip in softer OSB or along windward edges.

• Recommended fastener: #10 or #12 metal-to-wood painted roofing screws with EPDM washers and a Type 17 point.
• Typical length: 1-1/2″ often covers panel plus underlayment and achieves roughly 3/4″ to 1″ embedment in many residential assemblies. Remember to verify your stack-up.
• Spacing: Field rows about 24″ on center; eave and ridge rows about 12″ on center; corners or high-wind areas may require 6″ on center. Verify per ASCE 7 and manufacturer guidance.
• Technique: Drive in the flats, keep screws perpendicular, and set washers snug, not crushed.

Pro tip: If you plan to add snow guards later (such as Snow Defender devices), keep fastener materials consistent by using the same EPDM-washered, painted-head screws sized for your wood deck. This way, seals and appearance match across the roof.

Scenario 2: Commercial Building on Steel Purlins

You’re fastening 26-gauge R-panel to 14-gauge steel purlins. That’s a metal substrate, and the combined thickness (panel plus purlin) calls for Tek #3 at minimum. Many crews standardize on #12 or #14 Tek #3 for this application; step up to Tek #4 if purlins run thick or you’re drilling through overlapping layers.

• Recommended fastener: #12 MetalGrip metal-to-metal screws with Tek #3 for typical purlins; use Tek #4/#5 if you’re engaging thicker structural components.
• Typical length: 1″ to 1-1/2″ depending on panel rib depth and purlin thickness, ensuring full penetration and thread formation in the purlin.
• Spacing: Follow the panel supplier’s pattern; a common baseline is 24″ on center in field zones and 12″ at eaves and ridge, tightening at corners per ASCE 7.
• Lap screws: Use smaller Tek #1 to #2 stitch screws at side laps with sealant tape as required by the panel manufacturer.

Crew efficiency tip: Keep multiple Tek ratings on-site. If you hit a thicker girt or stacked steel, jumping from Tek #3 to Tek #4 prevents head snaps and delays.

Scenario 3: Pole Barn on Pressure-Treated Lumber

You’re installing 29-gauge panels on pressure-treated 2×4 purlins. The substrate is wood, so Type 17 metal-to-wood screws are correct. Because treated lumber can corrode some coatings, confirm finish compatibility or upgrade to stainless steel where warranted.

• Recommended fastener: #12 metal-to-wood screws with EPDM washers for stronger grip in soft or wet lumber.
• Typical length: 1-1/2″ to 2″ depending on purlin thickness to ensure 1″ embedment.
• Finish: Exterior-grade coating compatible with treated wood; consider 304 stainless or bimetal in aggressive exposures.
• Spacing: Follow manufacturer and local load requirements. That means 24″ on center in the field, with tighter spacing at eaves, ridge, and corners (per ASCE 7).

Durability tip: If the building is open-sided or high-moisture, slightly increase the diameter and length, and choose EPDM washers to maintain seals during seasonal movement.

Scenario 4: Metal Roof Repair and Re-Screwing

You’re chasing leaks on an older exposed-fastener roof. Washers are flattened, a few screws spin, and some holes are slightly enlarged. Repairs call for fresh washers and upsized replacement screws that re-bite into the substrate without over-enlarging the panel holes.

• Recommended fastener: #14 FastGrip Replacement Metal Roofing/Siding EPDM Washered Screws. Oversize to re-grip in slightly wallowed wood holes and reseal.
• Substrate check: Confirm whether you’re anchoring into wood or steel. If it’s steel, use an appropriately sized Tek metal-to-metal replacement. If it’s wood, an oversized Type 17 is the answer.
• Technique: Remove failed screws, inspect holes, place a small square of butyl tape under the panel if the hole’s borderline, then drive the #14 replacement snug. Don’t rely on caulk alone.
• Audit: Replace any screw that’s angled, stripped, or has a cracked washer. Don’t cherry-pick only obvious leaks.

Pro tip: If you find many stripped steel purlin holes, step up to a #14 Tek or shift slightly off old lines to fresh steel, following engineering guidance and the panel’s hole coverage limits.

Scenario 5: Coastal or Corrosive Environment

You’re installing in a coastal zone with salt-laden air. Corrosion risk is high, UV is intense, and wind loads often run elevated. Material selection is just as important as screw type.

• Recommended screw materials: 316 stainless for exposed fasteners within about three miles of saltwater; 304 stainless suits many inland or fringe coastal sites. Bi-metal screws combine a carbon steel drill tip with a stainless body for drilling performance and corrosion resistance.
• Washer material: EPDM only; neoprene dries and cracks sooner in harsh sun.
• Tek selection: Choose by steel thickness as usual; stainless or bi-metal options are available in common Tek points.
• Budget planning: Expect a 20 to 30% premium for 316 stainless over 304, and two to three times the cost of coated carbon steel overall. Remember, though, you’re buying service life to match the roof.

Wind tip: Tighten fastener spacing per ASCE 7 in perimeter and corner zones; follow the panel manufacturer’s high-wind patterns.

What Happens When You Choose Wrong (And How to Prevent It)

Using the wrong screw can turn a straightforward installation into a series of leaks, loose panels, and costly callbacks. Here’s what usually goes wrong when wood screws meet steel or Tek screws meet wood, along with the simple selection checks that can prevent those failures.

Metal-to-Wood Screws on Metal Substrates

Type 17 points don’t drill steel. On purlins, they skid, dull, or snap. Even if the panel hole opens, the screw won’t form threads in steel, so it won’t hold. Expect loose washers, leaks, and a peppered panel where both appearance and waterproofing suffer. Prevention is simple: if you’re anchoring into metal, use Tek-point, metal-to-metal screws matched to your steel thickness.

Metal-to-Metal Screws on Wood Substrates

Tek tips excavate too much material in wood, and the fine threads don’t bite fibers well. Result: poor holding that worsens as wood cycles through wet and dry seasons. Screws back out, washers lift, and leaks start at wind-exposed edges first. Prevention: if the anchor is wood, use Type 17 metal-to-wood screws with coarse threads.

The Real Cost of Fastener Failures

Swapping a spec on paper can cost thousands in the field. Callbacks often run $500 to $2,000 in labor and travel. A single persistent leak can cause over $10,000 in interior damage, not counting reputation hits or warranty disputes when the wrong fastener was used. Spend the extra dime per screw, choose EPDM washers over neoprene, and right-size the Tek point, and your future self will thank you.

Supply Maverick: Your Partner for the Right Fastener

Finding the right fastener shouldn’t slow down your project. Supply Maverick helps contractors and DIYers source the specialized metal roofing and siding components they need without the big-box runaround. With hard-to-find inventory, wholesale pricing, bulk value, and same-day shipping on most orders placed before 12 p.m. EST, you can keep the material side of the job moving.

Extensive Inventory of Both Types

We stock the everyday workhorses and the hard-to-find heroes: Type 17 wood-to-metal screws in #9, #10, and #12 diameters; Tek #1 to #5 metal-to-metal screws in #12 and #14; extra-long Tek #4 and #5 for structural steel; painted heads to match our panel colors; bi-metal stainless for corrosive sites; and oversize repair options like #14 FastGrip for worn-out holes. Need snow guards? We carry the Snow Defender line and the fasteners to mount them right.

Contractors and DIYers both win here: you’ll find what big-box stores don’t carry, without waiting weeks for a backorder.

Same-Day Shipping Keeps Your Project On Schedule

Order before 12 p.m. EST and most fasteners ship the exact same day, so your crew stays productive and your schedule stays intact. We ship across the US, Canada, Australia, and New Zealand, and we keep quantities deep so you’re not left short mid-project.

Expert Guidance Backed by a Major Manufacturer

Supply Maverick is the e-commerce division of Mid-Michigan Metal Sales, so you’re getting recommendations grounded in real manufacturing and field experience. Not sure whether you need a #12 MetalGrip Tek #3 or should step up to Tek #4? Debating between 304, 316, or bi-metal for a seaside project? Contact with your panel details and the exact product name or SKU you’re considering and we’ll get you dialed in fast.

Wholesale Pricing That Won’t Break the Bank

You’ll see wholesale pricing and bulk discounts on our site, plus Net 30 accounts for qualified contractors. Our goal’s simple: premium fasteners, hard-to-find inventory, and value that makes sense for both pros and weekend warriors.

Installation Tips and Best Practices

The right fastener only performs as well as it’s installed. These practical checks help you protect the panel finish, seal the washer correctly, and keep the job moving. You’ll also find guidance on tool selection, drill speed, screw placement, quality control, and post-installation maintenance.

Pre-Installation Checklist

• Confirm substrate type (wood or steel) and choose the correct screw family (Type 17 or Tek).
• Verify the Tek rating matches total steel thickness if fastening to metal.
• Confirm length for required embedment (wood) or full thread formation (steel).
• Choose EPDM washers for long-term sealing, especially in high-UV or coastal areas.
• Check color and head style for exposed-fastener applications.
• Map your fastening pattern per ASCE 7 zones: corners, perimeters, and field.
• Stage tools: variable-speed drill, correct driver bit, magnetic nutsetter, and personal protective equipment (PPE).
• Plan for chip cleanup and panel protection.

Proper Fastening Technique

1. Align the panel so fastener lines land squarely on purlins or layout marks; clamp if needed to prevent creep.
2. Hold the drill perpendicular to the panel; start slowly to avoid point walking, then increase the speed to 2,500 RPM max.
3. Let the point do the work: pierce wood (Type 17) or drill steel (Tek) without excessive force.
4. Watch the washer as the head seats; stop when the EPDM slightly compresses, and don’t crush it flat.
5. Place fasteners in the flats where the panel bears on the substrate, not on rib crowns.
6. Clear swarf and filings from the panel as you go to protect the finish.

Quality Control During Installation

• Spot-check torque: randomly inspect screws to ensure washers are snug but not over-compressed.
• Look for angled fasteners and correct them immediately.
• Inspect lap seams and trims for stitch screw placement; add sealant tape per the panel manufacturer’s detail.
• Verify spacing in roof zones matches the layout; tighten patterns at eaves, ridges, and corners as required.
• Replace any screw that spins out or won’t tighten; step up diameter or relocate slightly to bite material.

Post-Installation Maintenance

• Inspect the roof annually and after major storms. Be sure to check for backed-out screws, damaged washers, and flashing issues.
• Replace any fastener with a cracked or flattened washer; don’t try to “re-swell” seals by over-tightening.
• Remove debris and any lingering metal filings from installation.
• If repainting exposed heads for appearance, use a compatible touch-up system and follow the panel manufacturer’s guidance.

Metal-to-Wood Roofing Screws: Quick Reference Examples

Need a starting point for a wood-backed panel system? These examples can help you match a Type 17 screw to common residential, agricultural, and repair applications. Use the substrate, panel thickness, required embedment, and exposure conditions to confirm the final choice.

Example Product Fits for Wood Substrates

• #10 metal-to-wood painted roofing screws, Type 17 point, EPDM washer: Everyday residential wood-deck installs with 29- to 26-gauge panels.
• #12 metal-to-wood painted roofing screws, Type 17 point, EPDM washer: Higher-wind edges, softer OSB, or agricultural buildings needing more bite.
• #14 FastGrip Replacement Metal Roofing/Siding EPDM Washered Screws: For repair use where wood holes are slightly enlarged and need an oversize re-grip.

Metal-to-Metal Roofing Screws: Quick Reference Examples

For steel-backed panels, start with the steel thickness and let that guide your Tek point selection. These examples cover common commercial, structural, and stitch-screw uses, so you can quickly distinguish a purlin fastener from a lap screw or a heavy-duty structural option.

Example Product Fits for Steel Substrates

• #12 MetalGrip Tek #3: Standard commercial attachment into common purlins (about 18 to 12 gauge combined).
• #14 MetalGrip Tek #4 and #5: Heavy structural steel, retrofits into channels or I-beams, or stacked steel layers where extra penetration is needed.
• Tek #1 and #2 stitch screws: Panel side laps and trims where sheet-to-sheet attachment is required (use with sealant tape per panel details).

Final Thoughts

Matching the screw to the substrate is the simplest and most important decision you’ll make for a metal roof. Type 17, coarse-thread screws lock into wood; Tek, fine-thread screws drill and form into steel. Add EPDM washers, correct lengths, right-size Tek points, and materials suited to your environment, and you’ll get a roof that stays dry and trouble-free for decades.

Whether you’re a contractor bidding a tight schedule or a DIYer gearing up for a weekend build, Supply Maverick has the inventory depth, same-day shipping on most orders before 12 p.m. EST, and practical know-how to keep your project on track and your budget intact. We’re your metal supply source.

Frequently Asked Questions

Can I Use Metal-to-Wood Screws on Light-Gauge Metal?

Yes, if the anchor is wood. Type 17 metal-to-wood screws are designed to pierce 20- to 29-gauge roof panels and then bite into wood substrates. If the anchor is metal (purlins, Zs, beams), don’t use them; they won’t drill steel and won’t hold. Always match the screw family to the substrate you’re anchoring into.

Do I Need a Pilot Hole for Metal Roofing Screws?

Generally, no. Type 17 metal-to-wood screws self-pierce, and Tek metal-to-metal screws self-drill. Exceptions: with stainless or bi-metal screws into thick steel, a small pilot can prevent galling and reduce tip overheating. Follow the fastener manufacturer’s guidance. On delicate trim or very thin sheet-to-sheet stitches, a light pre-punch can prevent point walking.

What Size Screw Do I Need for My Metal Roof?

Match the screw to your substrate first, then size it:

• Diameter: #10 is common for residential wood decks; #12 adds grip in softer woods or high-wind edges; #14 is typical for heavy-duty steel or repair.
• Length: Include panel thickness plus underlayment and target embedment (wood) or full thread formation (steel). Many residential wood-deck installs land around 1-1/2″, but verify your exact stack-up.
• Tek rating (steel): Tek #3 is the go-to for many purlins; Tek #1 and #2 for stitch or lap; Tek #4 and #5 for heavy structural steel.

How Many Screws Do I Need?

Use your panel manufacturer’s pattern and verify with ASCE 7 roof zones:

• Field (interior) zones commonly run 24″ on center along supports.
• Eaves and ridge often tighten to 12″ on center.
• Corners or high-wind zones can tighten to 6″ on center depending on design wind loads.

A quick planning method: map the number of purlin or framing lines per panel length, multiply by fasteners per line per panel, then add five to 10% for waste and field adjustments. Always confirm with your panel supplier’s details and local code.

What’s the Difference Between EPDM and Neoprene Washers?

EPDM offers superior UV resistance and typically lasts two to three times longer under sun exposure than neoprene. Neoprene seals well initially but can dry out and crack as early as a decade into service, especially in hot, high-UV climates. In coastal and sun-baked areas, EPDM is the industry standard for exposed-fastener applications. Regardless of material, washers must be compressed snugly (never crushed) to seal and last.

Are Stainless Steel Screws Worth the Extra Cost?

In corrosive environments, yes. 304 stainless works well inland and in many general outdoor conditions. 316 stainless adds molybdenum for better chloride resistance and is the rule-of-thumb choice within about three miles of saltwater. Expect a 20 to 30% price premium for 316 over 304 and two to three times the cost of coated carbon steel overall, but you’re buying a fastener that can match the roof’s service life in harsh environments. Bi-metal screws offer a sensible compromise: a carbon steel drill tip for performance fused to a stainless body for corrosion resistance.

What Should I Do If My Metal Roof Screws Are Leaking?

1. Inspect the screws. Look for crushed or cracked washers, angled fasteners, and spinners that never tightened.
2. Determine the substrate. If it’s wood and holes are slightly enlarged, step up to an oversize replacement like a #14 FastGrip with an EPDM washer. If it’s steel, upsize the diameter and ensure the Tek point matches the thickness.
3. Replace, don’t band-aid. Pull the failed screw, clear debris, consider a small square of butyl under borderline holes, and drive a new screw straight and snug.
4. Check nearby seams and trims. Add stitch or lap screws and sealant tape per the panel details where needed.
5. If leaks persist or you suspect structural issues, consult a qualified local installer or engineer.

References

• Engineering Express. “What Are Tek® Screws?” Engineering Express, November 22, 2024. August 2026. https://www.engineeringexpress.com/wiki/tekscrews/