Understanding Deck Screws, Bolts, and Fasteners

Learn More About Deck Screws, Structural Bolts, and Deck Board Fasteners

Screws and bolts hold the world together - literally! Because the little guys have such important jobs, they come in wide varieties of shapes and sizes. Your backyard deck is constructed with a handful of specialty fasteners. Each of these has a specific purpose in ensuring you enjoy a well-built deck for years to come.

Whether you are a homeowner making a decision based on aesthetics and value, or a pro builder looking for the slickest installation options, we have you covered. So fasten your seatbelt and enjoy our guide to selecting the best deck fasteners for your project.

Quick Anatomy of Screws vs. Bolts

A simple distinction between these two fasteners is that a bolt passes through its anchoring material and receives a nut, while screws thread directly into their anchoring material. The head, neck, shank, thread coarseness, tip, and material/coating of both screws and bolts will vary according to their application. 

Stainless Steel Screws or Coated Steel Screws?

To stainless, or not to stainless? That is the question. Stainless steel screws provide the most corrosion resistance and are typically required in coastal applications. For most other applications, stainless steel is an optional and expensive upgrade.

Carbon Steel with Alkaline Copper Quant (ACQ) approved coating is the most common and recommended deck screw. The copper element in treated lumber destroys non-coated metals. Pro-tip: keep this in mind when other metal decking products, such as railing posts and flashing, come into contact with treated lumber. A small scratch left uncoated can lead to a costly repair down the road. Coated Screws are also stronger and less expensive than stainless steel fasteners.

With these basics covered, let’s dive into the world of deck specific fasteners.

Decking Installation - Face Screws or Hidden Fasteners?

Face Screws

Basic Deck Screws are used to hold down your decking material in a face screwed application. This is the tried and true, old-fashioned way. There are a few key considerations for this type of decking installation.

Pros and Cons of Face Screwed Decking

Pros:

  • Ease and speed of installation
  • Maximum hold-down power (hurricanes, extreme winds, etc.)

Cons:

  • Aesthetics - Screw heads remain visible
  • As your deck experiences seasonal expansion and contraction, screw heads can become exposed
  • Introduces an entry point for moisture into the deck’s surface, which can shorten the lifespan of wooden decking

The Two Types of Deck Screws - Flat Head Screws & Trim Head Screws

Deck Screws come in flat head and trim head designs. Flat head screws offer a slightly larger head than Trim Head screws and will drive to a flush finish on the top of your material. Trim head screws are very similar to Flat head screws but with one major difference, they’re designed to eliminate dimpling while disappearing beneath the surface of your decking. Trim Heads can also be used with plug systems to make them virtually disappear.

Flat-Head Deck Screws:

  • Most hold-down power
  • Often used with pressure-treated decking

Trim-Head Screws:

  • Most visually appealing
  • Less mushrooming effect
  • Often used with cedar and composite decking

Hidden Deck Fastener Systems

For those who love the clean look of a fastener-free deck surface, hidden fasteners are the way to go. The aesthetics and smooth walking surface of your decking is retained. You will not have unsightly screws to look at or trip over. 

Pros:

  • Smooth surface
  • Maintains integrity of the decking surface
  • The best option for maintaining most composite decking manufacturer warranties

Cons:

  • Higher cost
  • Slower installation

There are a wide variety of hidden fastener systems available. We’ve put together an infographic to help you decide which system is best for your application.

Hidden Deck Fasteners attach your deck boards in place while keeping the hardware hidden from sight

The Short Version - Face-Fastening Screws vs. Hidden Deck Fasteners

When should you face mount your decking?

  • When cost is the primary factor
  • When required by building code

When should you use a hidden fastener system?

  • When aesthetics are the primary factor
  • When maintaining the warranty of composite decking is important

Framing Fasteners

Even though framing fasteners are often an afterthought when constructing a deck, choosing the right screw or bolt will ensure a solid foundation for your deck.

Ledger Attachment

Through-bolts or ledger screws are used to attach a deck’s ledger board to the house. Through-bolts are used when the interior of the wall cavity is accessible during installation. Ledger screws function like lag bolts and are driven into the home’s rim joist. Building code will determine fastener selection and will vary depending on where you live.

There are some innovative products in this category. ThruLok Screw Bolt By FastenMaster is one of them. ThruLok offers speedy installation with the strength of a through-bolted connection. No need for pre-drilling or for a second person to hold a wrench, simply install with a drill in seconds. ThruLoks are a great choice anywhere you would use a traditional carriage bolt and nut.

General Purpose Deck Screws

Basic flat head decking screws are commonly used for most framing applications. This includes joist, blocking and stair stringer installation. The most popular screws we sell for this purpose are the R4 Deck Screws By GRK Fasteners.

Structural Screws

Often used in place of traditional lag bolts, Structural Screws are used for load-bearing applications such as attaching a deck’s beams to its structural posts. They can also be used for ledger attachment, and for other outdoor structural projects like building retaining walls or for log and timber framing. The 5/16" RSS Rugged Structural Screw by GRK Fasteners is one of our top sellers in this category.

Concrete Fasteners

There are two main types of concrete fasteners used in deck construction - anchor bolts and concrete screws. Anchor bolts can either be set in the concrete while it is poured and wet, or drilled and set into place using the wedge bolt variety. Concrete screws are very similar to general purpose construction screws, but have special threading and require a masonry drill bit for installation.


More Deck Project Resources