Deck Screw Guide: 12 Things You Need to Know
Has it been a while since you built your last deck? Did you fasten the wooden deck boards with nails or Phillips-head screws? Did you nail on joist hangers? Those days are over, my friend.
We met with some deck pros, who gave us the lowdown on the new screws they’re using to hang ledgers, secure posts and fasten metal connectors. They also gave us terrific insight into which deck screws and fastening systems they preferred for wood and synthetic deck boards. We guarantee you’ll find something here that will help you build your next deck faster and stronger—and make it look like a million bucks.
Structural Screws Outperform Lag Screws
Lag screws and washers have long been the fastener of choice for securing joists to posts and ledger boards to walls. Lags work fine, but they require a predrilled hole and lots of hand wrenching or an impact wrench.
Modern structural screws have auger stips and highly engineered threads that rip through wood fibers with very little force and no pre-drilling. Many can be installed with cordless drivers. Structural screws have wide heads that work like washers and are made of steel with tremendous shear strength. The ones shown here are made by GRK.
Hide the Screws
Hidden fastening systems are great, but there’s no more secure way to fasten a deck board than by screwing directly through the board into the framing. That’s why the Cortex Hidden Fastening System is our experts’ favorite. The boards are held down with composite deck screws that countersink themselves. The holes are then filled with plugs cut from the exact material the deck boards are made from, making them virtually disappear.
Upgrade to Composite Deck Screws
These are the features to look for in the screws you use to secure your composite, capped composite and PVC deck boards:
- An auger tip bores out the material as the screw drives through the material.
- Reverse threads help secure the deck board to the framing and pull down the shavings so they don’t get trapped under the head and cause mushrooming.
- An undercutting head slices through the surface so the screw can be sunk flush or countersunk without distorting the surface.
A star or hex head has six points of contact instead of four like a Phillips or square-drive, helping you avoid stripping the screw. Our experts prefer the TrapEase 3 screw shown here. It uses a proprietary Torx drive system called “TORX ttap,” which consists of a button at the bottom of the driver that fits into a recess in the screw head. It ensures that the bit is always centered in the screw head, almost eliminating stripping and cam-out. These screws come in a box with a lid that functions as a board spacer and screw alignment guide. They’re available in 17 colors at some home centers, lumberyards and online retailers.
It's a Screw And a Bolt
Are you a nuts-and-bolts kind of deck builder? Don’t trust structural screws on your deck frame?
Well, here’s a product that combines the best of both worlds. The ThruLOK structural screw can be driven into lumber without a pre-drilled hole. It also has a special nut that threads onto the end of the screw/bolt, sandwiching the framing components together. It’s perfect for handrail posts, which can be subjected to extreme lateral force.
Hidden Deck Board Fasteners
Here’s our advice for choosing among the many hidden fasteners available:
- Pick a fastener that can be used with grooved boards. Some hidden fasteners don’t work with deck boards that have a groove on the sides.
- You must use a hidden fastener that’s approved for the type of decking you’re going to use.
- Choose hidden fasteners that allow you to remove an individual board that has been damaged. Some hidden fasteners require removal of all the boards installed after the one that needs replacing.
- Look for topside installation. Some hidden fasteners are installed on the bottom of the deck boards. This is a problem for decks that are high in the air or low to the ground.
Be Prepared for Stripped Screws
If you drive in hundreds of screws, you’re bound to strip out a few of them. Pick up a screw extractor before you get started. All you need to do is smooth out the inside of the screw head with the burnishing end of the bit, then flip the bit around and back out the screw. As the bit turns counterclockwise, it digs down into the screw head, creating a very strong connection. The one shown here is an Alden Grabit, but there are other brands.
Buy Screws Compatible With Treated Lumber
The preservatives in pressure-treated lumber cause many metals to corrode. If you’re buying screws labeled “deck screws,” they’re probably compatible with your framing lumber. But if you don’t see “ACQ [Alkaline Copper Quaternary] compatible” on the package, don’t buy them. Stainless steel is the least corrosive material for screws, but stainless steel screw heads are softer and more prone to stripping, so they work best with pre-drilled holes.
A Perfect Hole Every Time
When working with rock-hard decking materials like ipe, our experts pre-drill holes in the wood with Starborn Industries’ Smart-Bit pre-drilling and countersinking tool. It has a rubber face and a free-spinning collar, so it won’t damage the surface of the wood. Starborn makes Headcote colored stainless steel trim-head screws that work with the bit, but any No. 7 trim-head stainless screw will work. This bit comes in handy for general woodworking projects as well.
Screw + Nail = Scrail
That’s right—a screw that’s driven in like a nail. These scrails work with the Tiger Claw hidden fastener system, which is arguably the fastest deck installation system available. A clip is slid onto the end of a special pneumatic gun. The clip is then inserted into the side groove of a deck board and fastened to the joist with a scrail. The scrail holds as well as a ring-shank nail but can be removed like a screw if a damaged board needs to be replaced. Pretty cool system, huh? But before you get too lathered up over it, know that the gun costs about $300.
Connector Screws Work Better
Most joist hangers and other metal connectors require a lot of fasteners to hold them in place. These connectors are often in awkward locations with little or no room to swing a hammer. To avoid smashing your fingers, install your connectors with screws instead of nails.
The Perfect Option for Wet Wood
Here’s a cool, inexpensive tool for fastening wood deck boards. In addition to being fast and easy to use, the Camo Marksman Edge Tool drives the screw into the top corners of the boards, which makes the heads hardly noticeable. This is a great feature because it’s not easy to hide fasteners on wood you want to install without a gap (wet treated pine and other soft woods like cedar shrink and create a gap after they dry).
The Marksman Edge Tool attaches to any drill. All you need to do is slide a screw up into the tool, hook the tool onto the edge of the board and drive the screw home. The pro version has a long handle and collated nails for super-fast, stand-up installation.
Wood Deck Screws
These wood deck screws work great for fastening wooden deck boards and are economical as well. They are the ones that most closely resemble the deck screws of old, but a closer look reveals the improvements. These DeckMate screws feature a Torx drive head, an auger tip, cut points on the treads to reduce resistance, and cutting nibs under the head that act like a countersink bit.