What Nails to Use for Composite Decking: Essential Guide

Quick Summary: For composite decking, use specialized composite deck screws designed for the material. Avoid standard wood nails. These screws are corrosion-resistant, color-matched, and engineered to prevent cracking and ensure a secure hold. Always check your composite decking manufacturer’s recommendations.

Building a composite deck is a fantastic way to upgrade your outdoor space. It looks great and is generally low-maintenance. But when it comes to fastening that beautiful composite material, a common question pops up: what nails or screws are best? It can feel a little confusing, especially when you’re new to composite projects. You want to make sure you get it right the first time so your deck stays strong and looks amazing for years. Don’t worry, I’m here to clear things up! We’ll walk through exactly what you need to know to choose the perfect fasteners for your composite decking project. Let’s get started on building that dream deck!

Understanding Composite Decking and Fasteners

Composite decking is made from a mix of wood fibers and plastic. This blend gives it durability and resistance to rot and insects, unlike traditional wood. Because of this unique composition, it behaves differently than plain lumber. This means the fasteners – the screws or nails that hold your deck boards in place – need to be specifically chosen to work with the composite material, not against it.

Using the wrong fastener can lead to a whole host of problems. You might end up with boards that split, fasteners that rust and stain your deck, or a deck that doesn’t feel as secure as it should. The goal is to have a deck that stays beautiful and strong, weathering the elements without degrading. That’s where choosing the right fastener comes in.

Why Standard Nails Aren’t Ideal for Composite Decking

You might be tempted to grab a box of standard galvanized nails, especially if you’ve used them for wood projects before. However, standard nails aren’t the best choice for composite decking for several important reasons:

• Material Compatibility: Composite materials can expand and contract with temperature changes. Nails, being rigid, don’t offer the same flexibility of movement as screws, increasing the risk of cracking the composite boards over time.
• Corrosion Risk: Many standard nails are coated, but this coating can wear off or corrode, especially in outdoor environments exposed to moisture. This leads to rust stains that are difficult to remove and can mar the appearance of your new deck.
• Holding Power: While nails offer some holding power, screws generally provide a much stronger and more secure grip, which is crucial for deck boards that experience a lot of foot traffic and environmental stress.
• Installation Difficulty: Driving nails into composite can sometimes be more challenging and can lead to over-driving, which damages the board surface.

The Best Choice: Composite Deck Screws Explained

When it comes to composite decking, the clear winner is a specialized screw. These aren’t your average construction screws. They are engineered specifically for the demands of composite materials. Let’s break down what makes them so good.

What to Look for in Composite Deck Screws

Not all screws are created equal, especially when you’re dealing with composite. Here are the key features to look for:

• Corrosion Resistance: This is paramount. Composite decks are outdoors, exposed to rain, sun, and humidity. Look for screws made of stainless steel, coated steel (often with ceramic or other advanced coatings), or heavily galvanized materials. Stainless steel is generally the top-tier option for longevity and stain prevention.

• Head Design: Many composite screws feature specialized heads. Some have a self-countersinking design, meaning they drive flush with the surface without needing a pilot hole or a countersink bit. Others have a bugle head that compresses the material for a clean finish. The goal is a smooth surface that won’t snag or cause tripping hazards.

• Thread Type: The threads on composite screws are often designed to cut cleanly through the composite material without creating excessive friction or heat, which can otherwise damage the board. Some have sharper threads for initial bite and coarser or self-tapping threads to hold better.

• Length and Gauge: The length depends on the thickness of your composite deck boards and how they attach to the joists. Generally, you want a screw that goes through the deck board and at least 1 to 1.5 inches into the sub-structure (joist). The gauge (thickness) should be appropriate for the load; a #8 or #10 gauge screw is common for decking.

• Color Matching: Many manufacturers offer screws in a range of colors that are designed to match their deck board colors. This creates a seamless, professional look. While functionally not as important as corrosion resistance, it certainly boosts the aesthetics.

Types of Composite Deck Screws

You’ll primarily find two main categories of screws used for composite decking:

1. Face Screws (Visible Fasteners)

These are the most common type of screw you’ll see when building a deck. They are driven directly through the surface of the deck board and into the joist below. For composite decking, these are typically specialized screws with the features mentioned above: corrosion resistance, specialized heads, and often color matching.

• Pros: Generally the strongest and most secure fastening method when done correctly. They provide excellent holding power.
• Cons: The screw heads are visible, which some people find less aesthetically pleasing.

When using face screws, it’s crucial to pre-drill if your composite manufacturer recommends it or if you’re using a screw without a self-drilling tip, especially with harder composites. A good rule of thumb is to drill a pilot hole about the size of the screw’s shank (body), not the threads. This prevents the board from cracking when the screw is driven in.

2. Hidden Fastener Systems

These systems are designed to attach deck boards from the side or underside, leaving a clean, smooth surface with no visible screw heads. There are various types:

• Scoring/Groove Systems: Some composite boards come grooved on the sides. Special clips or fasteners slide into these grooves and then attach to the joists. For example, the Trex Hideaway System uses clips that fit into grooves in Trex boards and attach directly to the joists.
• Underside Fasteners: Other systems use a bracket that attaches to the joist and then grips the underside or edge of the deck board.

• Pros: Creates a very clean, smooth, and modern look. No visible fasteners means a sleek surface perfect for bare feet or entertaining.
• Cons: Can be more expensive than standard screws. Installation can sometimes be more time-consuming or require specific tools. Holding power can vary depending on the system; it’s vital to choose a reputable system.

If you’re aiming for that “picture-perfect” deck with no visible screws, a hidden fastener system is the way to go. Always follow the specific instructions for the system you choose, as they can vary significantly.

Recommended Fasteners and Brands

When you’re out shopping, you’ll see a variety of brands. While this isn’t an exhaustive list, here are some reputable brands known for making quality fasteners suitable for composite decking:

Top Brands for Composite Deck Screws

• Trex: Offers a comprehensive line of fasteners, including color-matched screws and their proprietary hidden fastener systems designed to work seamlessly with their deck boards.
• Trex Deck Screws: Specifically designed for Trex decking, these screws feature a unique head designed for smooth driving and a patented cutting tip.
• Deckmate: A popular choice for composite decking, Deckmate screws are known for their corrosion resistance, color matching, and features like self-tapping tips and specialized heads to prevent mushrooming (where the material gets pushed up around the screw head). They have a specific line for composite.
• FastenMaster: Known for their high-performance fastening systems, FastenMaster offers screws like the TimberLOK and other specialized deck screws that are engineered for strength and durability in outdoor applications, often suitable for composite.
• Grip-Rite: Offers a range of construction fasteners, including exterior-grade screws that can be suitable for composite decking, often at a more budget-friendly price point. Ensure you select a corrosion-resistant option.
• Spax: Known for their innovative screw designs, Spax offers exterior-grade screws with good corrosion resistance and features that promote easy driving and preventing splitting, which can be beneficial with composites.

What About Nails? (A Gentle Reminder)

Just to reiterate, generally, you should avoid standard nails. If your composite manufacturer specifically states that certain types of nails are acceptable (which is rare, and usually involves specialized clipped-head nails for framing, not deck boards), follow their guidance precisely. For the deck boards themselves, screws are the way to go. The strength and flexibility they offer are key to a long-lasting composite deck.

Installation Guide: Using the Right Fasteners Effectively

Picking the right screw is half the battle. Installing them correctly is the other half. Here’s a breakdown of how to get it right:

Step-by-Step Installation Using Composite Deck Screws

1. Check Manufacturer Guidelines: This is your first and most important step. Always consult the installation manual for your specific composite decking brand. They will specify recommended fasteners, spacing, and any special installation requirements. Reputable manufacturers often have detailed guides available on their websites.
2. Gather Your Tools: You’ll need a good quality cordless drill/driver, appropriate driver bits (usually Torx/star drive for composite screws), a tape measure, a level, and potentially a chalk line. A screw gun can also be helpful for driving screws consistently.
3. Layout Your Deck Boards: Position your first deck board, ensuring it’s straight and aligned with your deck frame. Check for any factory edges that might need particular attention.
4. Spacing: Ensure proper spacing between deck boards. Manufacturers recommend a gap (often 1/8 to 1/4 inch) to allow for expansion and contraction. Using a spacer tool can help maintain consistent gaps. Spacing also applies to the distance from the edge of the board to the joist for fasteners.
5. Fastener Placement:
   • Face Screws: For boards running perpendicular to joists, place screws about 3/4 to 1 inch from the edge of the board. Drive them into the center of the joist. If you have narrower composite planks, you might place two screws per joist, spaced a few inches apart.
   • Hidden Fasteners: Follow the specific instructions for your hidden fastener system. This usually involves attaching the fastener to the joist and then securing the board to the fastener.
6. Drilling Pilot Holes (If Necessary): If your composite manufacturer recommends pilot holes or you’re using screws without self-drilling tips, drill them now. The pilot hole should be slightly smaller than the screw’s shank (the solid part without threads). This prevents the composite from cracking. For many modern composite screws, pilot holes are not needed.
7. Driving the Screws:
   • Set your drill/driver to a moderate speed.
   • Drive the screw until it’s flush with the surface of the composite board or slightly countersunk, as per the manufacturer’s recommendation. Do NOT over-drive the screw, as this can damage the board and weaken the hold.
   • For hidden fasteners, ensure they are securely engaged with both the joist and the deck board according to the system’s design.
8. Repeat: Continue this process for all your deck boards, ensuring consistent spacing and secure fastening.

Common Mistakes to Avoid

• Using the Wrong Fastener Type: Again, skip standard nails and generic wood screws.
• Over-Driving Screws: This is a very common mistake that can create divots and weaken the board. Aim for a flush finish.
• Under-Driving Screws: Leaves a bump that can be a tripping hazard and looks unprofessional.
• Not Allowing for Expansion/Contraction: Forgetting spacing can lead to buckling.
• Fastening Too Close to the Edge: Increases the risk of cracking, especially at the ends of boards.
• Not Pre-Drilling When Recommended: Can cause significant splitting in some composite materials.
• Using Uncoated/Non-Corrosion-Resistant Screws: Will lead to rust stains and premature fastener failure.

Fastener Considerations for Different Composite Decking Types

While the advice above is generally applicable, there are nuances depending on the specific type of composite decking you’re using. Composite decking has evolved, and there are now different generations and constructions.

First-Generation Composites

These are the older, more traditional composite materials. They tend to be harder and more brittle. For first-generation composites, it’s even more critical to:

• Use specialized composite screws with good corrosion resistance.
• Always pre-drill pilot holes.
• Consider using a lubrication (like wax or soap) on screws to help them drive more easily without excessive heat.
• Ensure screws are not over-driven, as they can easily crack the material.

Second and Third-Generation Composites (Capped Composites)

Modern composite decking, often called “capped composites,” has a protective outer shell or “cap” made of a durable plastic. This cap makes the boards much more resistant to staining and fading. While generally more forgiving than older types, it’s still essential to use the right fasteners.

• Specialized composite deck screws are still the best option.
• Many newer composite screws have self-drilling tips designed to cut through the cap and core easily.
• Hidden fastener systems are very popular with capped composites due to their sleek appearance.
• Always adhere to the manufacturer’s recommendations – some might still suggest pilot holes depending on the screw and the specific board profile.

Check out resources from organizations like the North American Deck and Railing Association (NADRA) that often provide best practices for installing various decking materials.

A Quick Summary of Fastener Options (Table format)

Here’s a look at the typical fastener options and their pros and cons for composite decking:

Frequently Asked Questions (FAQ)

Q1: Can I use regular deck screws for my composite deck?

It’s best to avoid regular deck screws if possible. Specialized composite deck screws are engineered with corrosion-resistant materials, unique thread designs, and specialized heads to work safely and effectively with composite materials, preventing cracking and staining.

Q2: What is the best type of screw for composite decking?

The best type is a screw specifically manufactured for composite decking. These are typically high-quality, corrosion-resistant screws (like stainless steel