Top 10 FAQs About Wood Fasteners Answered by Experts

Building wooden structures is our thing. Over 28 years, we've built hundreds of decks, fences, raised garden beds, and other outdoor wood structures. We've learned that most failures come down to one thing: choosing the wrong fastener or using it the wrong way. This guide answers the exact questions we hear from DIYers and professionals every single day.

Skip to Your Question

• FAQ #1 — What do those screw numbers (#6, #8, #10) mean?
• FAQ #2 — How long should the screw be?
• FAQ #3 — Should I pre-drill?
• FAQ #4 — What fasteners work for different wood types?
• FAQ #5 — Stainless vs galvanized vs coated—which lasts?
• FAQ #6 — How much weight can one screw hold?
• FAQ #7 — Can I use drywall screws?
• FAQ #8 — How do I drive wood screws the right way?
• FAQ #9 — Is it worth paying more?
• FAQ #10 — What's the best wood screw for MY project?

FAQ #1: What Do Those Numbers Mean? Understanding #6, #8, #10 Screws

You're at the hardware store, staring at bins labeled #6, #8, #10, and you have no idea which one you need. Sound familiar? You're not alone—most DIYers are confused about this.

Here's the simple answer: The number (called the gauge) tells you the screw's diameter, or thickness. The higher the number, the thicker the screw. So a #10 is thicker than a #8, which is thicker than a #6. That's it. The length comes separately—like "2.5 inches"—and that's a different specification entirely.

Understanding the Gauge System

The first number represents the screw's diameter or thickness. The second part (like 1-1/2″) is the length of the screw, from the point to where it meets the surface of the material. This two-part naming gets confusing because some people say "#8 screw" when they mean just the gauge, but then you need the length too.

Here's what you actually need to know:

Why does this matter? A #6 screw is 0.138 inches wide. A #10 screw is 0.190 inches wide. That doesn't sound like much of a difference, but when you're working with different materials—like soft cedar versus oak—it matters a lot. The bigger the diameter, the more holding power you get, up to a point. But bigger also means more risk of splitting the wood if you're not careful.

Pro Tips from the Field

Use a screw gauge ($3 at any hardware store). Takes two seconds to identify what you've got sitting in the garage. Saves hours of guessing.

FAQ #2: How Long Should the Screw Be? 

You've probably heard this before: "The screw isn't long enough." Or worse, you drove it all the way through and now there's a hole in the back. How do you know exactly how long your screw needs to be?

Simple formula: Use the 2/3 Rule. About 2/3 of the screw should be threaded into the receiving (bottom) piece. For structural applications, engineers follow the 4D Rule—that's 4 times the screw's diameter as minimum penetration. But let's stick with 2/3 because it works for 95% of projects.

The 2/3 Rule, Explained

Here's how it works in practice:

You're fastening a 3/4″ board to another 3/4″ board. Using the 2/3 rule:

• Top board: 3/4″

• Required penetration into bottom board: about 1″ (which is roughly 2/3 of 3/4″ × 2)

• Total screw length needed: 1.75″ to 2″ (round up to 2.25″ for safety)

This rule exists for a reason: deeper penetration equals stronger holding power. The threads grip the wood better, and the screw won't pull out under load. Too short, and the joint is weak. Too long, and you puncture through the other side—or worse, the screw snaps off mid-drive because of resistance.

Why Penetration Matters More Than Thickness

Here's what surprises people: a longer #8 screw beats a shorter #10 screw almost every time. Penetration depth matters more than gauge size.

When building a deck, we calculate length differently because deck boards are fastened into joists, and penetration depth is critical. That's why for a 1" cedar deck board, we typically use a 2.5" to 3" screw—the extra length gives you that perfect penetration into the rim joist, whether you're using Eagle Claw, Simpson, or any other deck screw brand.

End Grain vs Side Grain (Critical Detail)

Here's something most DIYers don't think about: fastening into the end of a board is totally different from fastening into the side. End grain (like the rim joist of a deck) is harder and grips threads differently. Always aim for at least 2 inches of thread into end grain.

We learned this one the hard way—had a couple squeaking deck boards because we didn't penetrate far enough into the rim. Never again. Now we overcalculate for end grain.

FAQ #3: Should I Pre-Drill? 

Always pre-drill hardwoods. Always pre-drill near wood edges. Size your pilot hole to 80-90% of the screw's root diameter for hardwoods, and 50-70% for softwoods.

Why Pilot Holes Matter

When a screw drives directly into wood without a pilot hole, it exerts considerable pressure on the surrounding fibers. In denser woods or when working near board edges, this pressure easily causes the wood to split along the grain.

A pilot hole relieves that pressure. The screw enters without forcing the wood fibers apart. It's like the difference between pushing a nail through paper and drilling a hole first—one tears, the other doesn't.

We use pilot holes on every deck we build. It's a $2 insurance policy against squeaking boards and catastrophic splits. Worth it every time.

Pilot Hole Sizing Chart

Here's the reference we use on every job:

Notice the pattern? Softwood pilots are bigger because the wood is softer. Your drill bit actually needs that extra room to avoid forcing the screw. Hardwood pilots are smaller because oak and maple resist penetration—the screw threads need to grip tightly.

The Tape Trick (Pro Move)

Mark your pilot hole depth by wrapping a piece of tape around your drill bit. For a #10 screw in a rim joist, we mark the bit at about 2.5 inches from the tip. Drill until the tape touches the wood. This prevents you from drilling through the other side accidentally (especially on thin materials).

We use this constantly on cabinet doors where accuracy matters.

FAQ #4: What Type of Fasteners Work Best for Different Wood Materials?

Not all wood is the same. The type of wood you're fastening determines your gauge size and material choice.

Softwood (Pine, Cedar, Fir)

Lighter, less dense wood. Lower holding power than hardwood, so you need deeper penetration to compensate. Cedar decks are a perfect example—use #8-9 gauge because that's plenty. Pre-drill within 1 inch of edges.

For decks: Cedar is softwood. Use #8 or #9 gauge, 2.5"-3" length (following the 3× thickness rule from FAQ #2). We recommend Eagle Claw #10 x 2.5" or #10 x 3" for cedar decks.

Hardwood (Oak, Maple, Walnut, Redwood)

Dense, slow-growing wood. Superior holding power, but requires mandatory pre-drilling. Skip the pilot hole on oak and the board will split—we've heard that crack before.

For decks: Redwood decks are beautiful but dense. Same gauge and length as softwood (#8-9 gauge, 2.5"-3"), but pre-drilling is non-negotiable with smaller pilot holes. The holding power is excellent.

Pressure-Treated Lumber

Regular wood (usually pine) injected with rot-preventing chemicals. The chemicals are acidic and eat fasteners. Bare steel fails in 1-2 years. You must use galvanized or stainless.

Material requirement: Hot-dipped galvanized (10-15 year life) or stainless 304/316 (25+ year life). Never mix galvanized fasteners with stainless connectors—they corrode each other.

For treated wood framing, Simpson Strong-Drive® SD Connector Screws in galvanized finish are the standard.

Composite Decking

Plastic-wood blend. Acts nothing like wood. Manufacturer specifications are exact—follow them. Too much force can crack the plastic surface or strip the fastener.

The rule: Read the installation guide. Use the exact fastener size and type they specify. This isn't the place to improvise.

Plywood and Sheet Materials

Engineered material with vulnerable edges. Edge grain doesn't grip threads like face grain. Larger fasteners don't help—smaller is often better here.

For plywood edges: Use #6 x 1" with a 3/32" pilot hole. For plywood faces: #8 x 1.5" works fine.

FAQ #5: Stainless vs Galvanized vs Coated, Which Is Better?

Use hot-dipped galvanized, coated, or stainless steel. NEVER electroplated zinc. Never mix metals.

Hot-Dipped Galvanized

Thick zinc coating, approved for treated wood. Cheap but shows age quickly—white rust dust after 10-15 years. Simpson Strong-Drive® SD Connector Screw in galvanized is the standard for covered structural work.

Coated Fasteners

Advanced surface coating without the thick zinc plating. Looks better than galvanized, performs similarly (10-15 years). Good mid-range option for budget builds. Deck-Drive™ DSV Wood Screws in coated finish offer solid value for inland, covered decks.

Skip coated for: Visible long-term fasteners (go stainless) or coastal salt spray (coatings break down faster).

Stainless Steel

Costs 5-10 times more per fastener but lasts forever. After 20 years, stainless looks brand new. Galvanized and coated show age.

304 grade: Standard, fine for most projects.

316 grade: Marine grade for salt water or extreme corrosion. Strong-Drive® SDS Heavy Duty Hex Connector Screw in 316 Grade is engineered for this.

Galvanic Corrosion

Never mix metals in the same assembly. Stainless screws with galvanized hangers. Coated with bare steel. Different metals accelerate corrosion on the weaker one.

Rule: Go all-in with one system. Don't mix.

FAQ #6: How Much Weight Can One Screw Hold? Understanding Withdrawal Strength

How much weight can a single wood screw hold? It depends on three things: the screw diameter, how deep it penetrates, and the wood density.

There's an actual formula: F = 2850 × SG² × D

Where F = withdrawal strength (pounds per inch of penetration), SG = wood's specific gravity, D = screw diameter.

Real Numbers You Can Use

A #10 screw (0.190" diameter) in yellow pine (specific gravity 0.55) yields: 56 pounds per inch of penetration. If the screw penetrates 2 inches, that's 112 pounds total holding force.

Same #10 screw in oak (specific gravity 0.75)? 103 pounds per inch. With 2" penetration = 206 pounds total.

Here's a full reference table:

Why denser wood holds better: More mass for the threads to bite into. Oak has significantly more holding power than cedar. It's not even close.

Practical Application Example

You're building a shelf to hold books. The shelf is 1/2" plywood fastened with #8 screws into a wall stud. Using the 2/3 rule, you can penetrate about 1.5" into the stud. If that stud is pine: 22 lb/in × 1.5" = 33 pounds per screw.

Install four screws and you've got 132 pounds holding capacity. Most bookshelves are fine with that.

But if someone loads 200 pounds of books onto a shelf designed for 100 pounds, those fasteners are just... hoping. That's why spacing and fastener count matter.

Why Lateral Load Is Different From Withdrawal

Withdrawal load (what we just calculated) is pulling straight out. Fasteners are good at resisting that.

Lateral load is sideways pressure (like a shelf bending under weight or a wind load on a fence). Lateral holding is weaker—maybe 40% of the withdrawal value. This is why building codes specify number of fasteners AND spacing. Multiple smaller fasteners resist lateral load better than one huge fastener.

Bond Between Wood and Fastener

The threads create friction and mechanical bond with the wood fibers. That's what holds the screw in place. This bond:

• Gets stronger the deeper you penetrate (more thread contact)
• Gets stronger with denser wood (more fiber density to grip)
• Gets weaker if you overscan with a pilot hole (lose thread bite)
• Gets weaker with fast spiral threads vs slow spiral (less surface contact)

FAQ #7: Can I Use Drywall Screws?

For outdoor work or structural fastening? No. For temporary interior work? Maybe, but even then, we wouldn't risk it.

Why Drywall Screws Fail

Drywall screws are engineered for one job: fastening drywall (which weighs nothing) to wooden studs (in a dry, temperature-stable environment). That's it.

Here's what makes them different from wood screws:

Thread design: Drywall screws have a fine thread (many threads per inch). This works great for gripping the thin paper and gypsum core of drywall. But on exposed wood, especially in high-load situations, that fine thread doesn't bite like a wood screw thread would.

Material: Drywall screws are often lower-grade steel. They're cheap because the application doesn't demand strength. A drywall screw will snap off if you put real pressure on it.

No corrosion resistance: Most drywall screws have minimal coating. Use them outdoors and they'll rust in months.

Tip design: Drywall screws have a drill-point tip (they drill through drywall without pre-drilling). That same tip can cause splitting in solid wood because it's designed to pierce, not guide the fastener in.

When Drywall Screws Might Work

Interior cabinet assembly, temporary bracing, light-duty indoor shelving where you know it won't see moisture or stress. Even then, we'd use proper wood screws. They cost the same and never fail.

The Holding Power Difference

In lab testing, drywall screws in wood pull out at about 60% of the force that properly sized wood screws can handle. For most applications, 60% is failure range. You're betting your project on a 40% safety margin—not great odds.

FAQ #8: How To Drive Deck Screws The Right Way?

After 28 years and hundreds of structures, we've seen every failure pattern imaginable. Most come down to installation mistakes, not fastener choice.

Mistake #1: Wrong Driving Speed

Driving too fast creates friction heat that softens wood fibers. You're essentially melting them around the screw. When the wood cools, the grip is weaker. You also increase splitting risk because the screw tip isn't being guided properly.

Our approach: Use steady, moderate speed. Let the tool do the work. If a screw is binding up, you're either:

• Hitting knots (unavoidable—slow down)
• Using a poorly designed screw
• Encountering wood movement (happened before, will happen again)

With a cordless drill, we typically run speeds around 800-1200 rpm for framing. Slower for hardwood. Fast for softwood.

Mistake #2: Insufficient Pilot Hole

We've covered this, but it bears repeating: undersized pilot holes cause splits that aren't visible until months later. By then, the board is finished and you're not replacing it.

When fastening on the end grain of boards (like deck rim joists), pre-drill without question. No exceptions.

Mistake #3: Too Close to the Edge

Putting a fastener within 1 inch of a board edge dramatically increases splitting risk. If you must fasten near an edge, use a smaller gauge screw and a properly sized pilot hole. Better yet, reposition if possible.

We've had entire deck boards fail because someone ran a fastener 1/2 inch from the edge of a rim joist. It split the whole thing.

Mistake #4: Inconsistent Spacing

Fasteners should be evenly spaced. Uneven spacing creates stress concentration. If you bunch fasteners on one end of a board and leave the other end bare, that bare end will lever and twist as the wood moves.

Building codes specify spacing for this reason—typically 16 inches for structural, 12 inches for load-bearing.

Mistake #5: Wrong Installation Angle

Drive fasteners perpendicular to the wood surface (straight in), not at an angle. Angled fasteners have less holding power because they're fighting the wood grain differently.

This one shows up on homeowner projects where someone was "just trying to get the screw to bite." Angle = weak fastening.

Mistake #6: Stopping Too Early

Screws should be driven all the way down until the head sits flush (or slightly countersunk, depending on design). Stopping halfway means the head is sticking up and the threads aren't fully engaged.

With composite deck screws, watch for the special head design—it's meant to sit flush or slightly below the surface, not left sticking out.

Mistake #7: Mixing Old and New Fasteners

Don't use rusty or corroded fasteners from old projects. The corrosion weakens them, and if you're using treated wood with old fasteners, you're asking for galvanic corrosion (we explained that earlier).

Buy new for every project. Fasteners are too cheap to take chances.

FAQ #9: Is It Worth Paying More for Better Fasteners?

You can buy a box for $5 or $50. What's the difference? Fasteners that cost more rarely fail. Cheap fasteners often do. For visible or critical work, paying more pays for itself. For hidden stuff, cheap works fine.

What You're Actually Paying For

Thread design: Better threads grip wood better—20-30% more holding power, same size screw.

Tip design: Quality tips are sharp and efficient. Cheap tips can deflect, causing angled driving and weak fastening.

Material quality: Better fasteners use better steel alloys. Cheap steel is softer and snaps easier during installation.

Surface coating: Quality coatings (like DSV’s Quik Guard™) last decades. Cheap galvanizing flakes in 5-10 years.

When Spending More SAVES You MORE MONEY

Visible fastening (decks, doors, railings):

Cheap fasteners rust and stain. You're repainting or replacing them in year 3-5. That's hours of labor. Quality stainless (Eagle Claw) stays perfect for 20+ years. Do the math.

Load-bearing or structural:

Fastener failure here is catastrophic. Replacing a deck joist costs thousands. Quality fasteners cost hundreds. Cheap insurance. Simpson Strong-Drive screws are engineered for exactly this.

Hard-to-access locations:

If you'd have to tear out finished material to replace it, spend the extra money. You're not doing that twice.

Treated wood:

Cheap fasteners corrode in treated lumber. We've re-fastened entire fences because someone used cheap fasteners. Quality ones from the start cost less long-term.

When Cheap Screws Are Okay

Hidden structural, temporary projects, interior dry environments, light loads. Cheap works when no one sees it and it won't fail catastrophically.

FAQ #10: What Fasteners Are Best for My Project?

This is the question we get asked more than any other: "I'm building X—what screws should I use?". 

We’ll teach you how to decide what are the BEST wood screws for your project.

We’re going to apply what you learned above and answer each question below until you know what’s the RIGHT WOOD SCREW for your SPECIFIC OUTDOOR PROJECT.

Question 1: What wood are you fastening?

If you're not sure what wood you have, ask at the lumberyard or check the receipt. Two minutes now saves headaches later. We always double-check before buying fasteners.

Question 2: What load are you resisting?

Most people underestimate lateral load. A fence in the wind or a deck with kids jumping isn't just fighting gravity—it's fighting sideways stress. That's why spacing matters so much.

Question 3: What's the environment?

Never use 304s when you actually live coastal!

Question 4: Is appearance part of the decision?

Honest truth: We'll spend $50 more on stainless for deck fasteners because I know the homeowner's going to look at that deck for 20 years. Same reason I won't overspend on fasteners hidden inside a wall.

Question 5: Are there code requirements?

Check code BEFORE you shop. Takes 10 minutes, saves thousands if you get it wrong. We had an inspector make someone pull an entire deck because fasteners weren't code-compliant. Not fun.

Question 6: What's your budget vs durability trade-off?

When you do this right, your projects last decades. We've built hundreds of them this way—decks solid after 20 years, framing holding strong, hinges smooth. It's because we matched the fastener to the job, not because we got lucky.

Pick your project, work through the framework, and you'll know exactly what to grab.

Building wood structures since 1997. We've learned what works.