How to Choose the Right Fastener for Your Deck (2023)

FAQs

What fasteners to use on deck? ›

A good all-around choice is #10 decking screws—generally in 2 1/2- to 3 1/2-inch lengths. Decking screws are sharp, tapered, self-sinking, and coated for corrosion resistance. With a cordless drill/driver, you can drive them about as fast as nails.

The general rule of thumb for standard deck fasteners is 350 screws for every 100 square feet of decking, which is based on standard 6" wide boards (5-1/2" actual), and 16" joist spacing.

Use three Trex recommended composite decking screws every 12". ALWAYS refer to manufacturer instructions to ensure that recommended screws can be used for fascia applications.

Picking the wrong fastener can severely impact the quality of your product or service and perhaps even cause your product to fail prematurely or cause you to be unable to fulfill delivery of your product.

In addition to the own weight of the system to be fastened and the loads to be applied, the base material is one of the most important factors in determining the suitable fastener.

A 3” length deck screws are preferable to 2.5” as they hold better. What is this? A #8 diameter deck screw is ideal, as any higher would split the wood. Remember, if you are using cedar, then you should opt to use a hidden fastening system as these coated screws will stain your cedar.

Fasteners for preservative-treated wood shall be of hot dipped zinc-coated galvanized steel, stainless steel, silicon bronze or copper.

Galvanized, ceramic coated, or stainless steel screws are the best corrosion-resistant fasteners for pressure-treated cedar or redwood.

Approved Fasteners

The International Residential Code lists two fasteners for directly attaching ledgers to a house: 1/2-inch-diameter hot-dip-galvanized hex-head machine bolts and 1/2-inch-diameter hot-dip-galvanized lag screws. Note that “carriage,” or “cap head,” bolts are not listed.

So, how many screws should you put per deck board? Each deck board should be fastened with two screws at each point where the board crosses a joist to ensure the stability and durability of your deck's surface. Boards should be fastened to rim joists with three screws.

How far apart should Trex fasteners be? ›

The minimum required width-to-width gapping is 6 mm. When installing in temperatures below 4.5°C, Trex recommends 10 mm gapping. For docks and heavily wooded areas, Trex recommends a 10 mm gap as well. No gapping should ever exceed 13 mm.

Use a 1/8” wood drill bit in the drill and drill a hole at 1” in from the edge of the deck board. The fasteners must be less that 16” on center.

Make sure you level both joists to the same height and fasten with 4 screws every 12" to support the composite butt joints.

Inch fasteners—those commonly used in North America—will have a grade or ASTM rating. Property class (often just "class") specifies metric fasteners. Special markings on screw heads and nuts identify the fastener's grade.

Bolts are the most common type of fasteners. These machine elements are usually used to hold two unthreaded components together. A bolt has external male threads on one end and a hexagonal head on the other. The bolt is normally fastened with a nut on the other end.

Wood screws – These are the most common wood fastener types and are specifically designed to attach wooden boards and planks. Sheet metal screws – These have sharper threads for more easily connecting metal to wood, plastic or other pieces of metal.

Rivets form a stronger and tighter joint than screws of the same diameter. As a result, they are ideal in applications that require strong mechanical joints like aircraft construction, aluminum watercraft, and military equipment.

BUMAX® Ultra – the world's strongest bolt

Since its launch in 2014, the BUMAX® Ultra range has proven that it is capable of exceeding tensile strengths of between 1 500 to 1 700 MPa on various applications, with good corrosion resistance and an operating range of between -50 and 400°C.

Typical drive types include Phillips, Square, Slotted, Torx/Star, or Hex/Allen Drives. The more engaged your drive type, the less prone your screw is to stripping or slipping off the bit when being installed.

Should you use screws or nails on deck joist? ›

Screws are superior for laying down the decking. They hold things flush better and have a better fastener/tensile strength, which keeps boards from popping up over time. However, unless you use more expensive structural screws you need to use nails for structural elements and joists.

Fastener Categories

Screws with a smooth shank and tapered point for use in wood. Screws with threads for use with a nut or tapped hole. Machine screws with a thread cutting (self tapping) point. Fully threaded screws with a point for use in sheet metal.

The manufacturers of ACQ, CA, ACZA and CCA and the treated wood industry are all recommending hot-dipped galvanized nails and stainless steel nails and screws with their treated wood products.

Simply put, ACQ-treated lumber is extremely corrosive to metal fasteners such as nails, screws, deck hangers, etc.

Hidden deck fasteners are a nice way to keep the surface of your deck looking clear and unencumbered. But they are not the right fastener for all decks. In fact, using hidden deck fasteners inappropriately is a formula for failure. Some deck projects require the stronger fastening power of face screws.

Bolts (at least 5 in. long for 4×4 deck posts, 2 bolts per post) Power drill. Long drill bit (same length as the bolts)

The fasteners must be compatible with pressure-treated lumber to prevent corrosion. Typically, you will need to install your bolts alternating high and low 2" from the top and bottom of the ledger board. As a rule of thumb, bolts can be spaced 16" on center for supporting joist span up to 12' in length.

Traditionally, lag screws have been the most common method of attaching decks to buildings. To properly attach a deck ledger using 1/2″ lag screws, 5/16″ holes need to be pre-drilled through the ledger and rim joist. After that, a 1/2″ hole should be drilled through the ledger only.

Since the width of the thread and circumference of the bolt are known, we can calculate the number of threads. Now we know the pitch of the threads and the number of threads, so we can calculate the threaded depth. As it turns out, this can usually be simplified to Threaded Depth = 1.5 x Diameter.

The letter 'M' indicates that this bolt uses a metric thread. The number '8' refers to the nominal diameter of the bolt shaft in millimeters. The number 1.0 is the thread pitch of the bolt, which is the distance between threads, in millimeters. And the final figure, 20, is the length in millimeters.

Is 4x4 enough support for deck? ›

In the past, many decks were built with 4x4 support posts (also called structural posts). But these can bow seriously, even if a deck is only 3 feet off the ground. For that reason, we strongly recommend that you use 6x6s instead, even if your building department does not demand them.

In the past, no matter what type of deck board you were installing, the answer to this question would indefinitely be yes. However, with advancements in fastener technology, pre-drilling in most composite and capstock deck boards is no longer necessary.

Decking Board Considerations

Decking boards span from joist to joist. If you use 5/4 decking, joists must be no farther apart than 16 inches. Decking with boards with a 2x4 or 2x6 span can be 24 inches. If you run decking at an angle, you might need to put the joists closer together.

Trex recommends the use of two screws per joist.

Use recommended stainless steel screws in any areas near bodies of saltwater. 2-3/4" or 3" screws can be used with Trex 2x6 product. Muro T-Screw M-TX0300SEP listed above is approved for 2x6 decking (can also be used with standard 1" (decking as listed above).

You won't ever need to seal or stain the deck, and you certainly don't have to (and shouldn't) paint it. And since Trex is a composite material, you don't have to carry out long-term maintenance such as replacing rotted deck boards.

Trex recommends the use of two screws per joist. All recommended screws are designed to be installed flush with decking surface.

NOTE: When using hidden fasteners (both start and connector clips), one must be used on every joist. ° # of joists x # of decking boards = # of connector clips needed.

ONLY pre-drill through the TREX itself. The screw won't seat in the board properly. Instead of sitting down flush with the board, it will stop at the top of the board and just spin.

The general rule of thumb for standard deck fasteners is 350 screws for every 100 square feet of decking, which is based on standard 6" wide boards (5-1/2" actual), and 16" joist spacing.

Working with 5/4 board (i.e. 1.25-inch thick lumber), means you'll end up with a planed and finished thickness of about 1.063 inches. This means you'll want to secure these pieces with a 4-inch screw if going into 6-inch joists.

How many screws do I need for a 2x6 deck? ›

Each board should recieve 2 screws per joist, spaced about an inch from each edge.

Length is measured from the point at which the head sits flat with the surface, to the tip of the threads. Hex, pan, truss, button, socket cap, and round head screws are measured from right under the head to the end of the threads. Flat head screws are measured from the top of the head to the tip of the threads.

There are three main types of threaded fastener; Bolts, Screws and Studs. Bolts have a head on one end (this is usually a hex head) and are threaded on the other.

ASTM's fastener standards are instrumental in specifying, testing, and evaluating the material, dimensional, mechanical, and metallurgical properties of the various forms of hardware fasteners.

The maximum spacing for bolts between painted members or unpainted members not subject to corrosion is 24 times the thickness of the thinner part (but not more than 12 in.).

The measure should be carefully positioned so as to ensure that the first mark on the measure (i.e. the mark representing zero) is aligned with one end of the length being measured. You are then looking for the mark on the measure that most closely aligns with the other end of the length being measured.

The total length of the screw should be in the range of 2¹⁄₄". When fastening two pieces of ³⁄₄"- thick stock together, I use 1¹⁄₄"-long screws. This gives you maximum holding power without any chance of poking through the lower surface.

BUMAX® Ultra – the world's strongest bolt

Since its launch in 2014, the BUMAX® Ultra range has proven that it is capable of exceeding tensile strengths of between 1 500 to 1 700 MPa on various applications, with good corrosion resistance and an operating range of between -50 and 400°C.

Grade 5. Manufactured from medium carbon steel and hardened for greater strength and durability, a grade 5 bolt is distinguished by 3 radial lines and promises tensile strengths between 105,000 and 120,000 psi. They are most commonly found in automotive applications or those that require medium strength.

Class 4 fasteners are needed in areas with discernible levels of airborne pollution or coastal areas with moderate to high salt levels. They should be able to withstand 2000 hours of salt spray/fog testing, without showing more than 5% red rust on the surface of the fastener head.

What is difference between fasteners and screws? ›

Fastener is a general term to describe something which is used as a restraint for holding things together or attaching to other things. The main physical distinction between screws and bolts is that screws are entirely full of threads while bolts contain shanks without threads.

The most common fasteners in use are the hex head Grades 2, 5, and 8. Grade 2 is standard hardware-grade steel. This is the most common grade of steel fastener, and is the least expensive.