Screws help to fasten things together, and unlike nails can be easily removed. However, not all screws are created equally.
When building a deck, getting deck screw sizes mixed up can mess up your project or home renovation, costing you time and money.
Deck screws are special screws that are specifically designed for deck construction.
They are threaded fasteners that consist of a head, shank, and tip and come in different sizes, shapes, and material.
Because they are made of corrosion-resistant material, deck screws are more durable and can lengthen the life of your deck.
Generally, these screws are made of stainless steel, a highly corrosion-resistant alloy, or copper, which is one of the strongest metals.
When purchasing deck screws, it’s important to get the proper size.
Screws that are too small won’t fully secure the planks of wood, while screws that are too long will stick out of the planks and could weaken the integrity of your deck.
Deck screw size charts have been invaluable in helping craftsmen save money while constructing sturdier, more reliable decks.
They’re a hassle-free way of determining the right screw size for your needs.
In this article, we’ll help you understand some terms that will make it easier for you to read a deck screw size chart, and ultimately make the right call when buying deck screws for your next project.
Picking the Right Deck Screw Size
Woodwork and outdoor project aficionados and professionals know the importance of using the right items and tools.
However, even expert craftsmen can doubt themselves when it comes to selecting the ideal materials, sizes, or tools to use.
When it comes to building decks, one of the most confusing aspects is selecting the right deck screw size.
Deck screws are different than regular screws and come in a range of different sizes and materials – so which one are you supposed to pick?
To understand how to read a deck screw size chart, you’ll first need to understand how deck screws are sized.
Here are some terms you need to know:
#1. Gauge
The “gauge” number on a box of deck screws refers to the diameter of the screws.
And as we not also on nail size charts, a higher gauge indicates bigger screws.
For deck screws, an 8-10 gauge is generally considered as standard. An 8 gauge is around 4mm in diameter.
You can also use 14-gauge screws, but don’t be confused as these are labeled with their actual diameter (¼-inch or approximately 6 mm).
#2. Length
After the diameter or gauge, the next thing to consider when choosing the right deck screw size for your project is the length of the screws.
As a general rule, when picking a screw length you should ensure that the screw will be able to completely penetrate one wooden plank and go about halfway into the second piece to securely fasten them together.
The standard length of deck screws can be anywhere between 1½ inches to 6 inches.
The length you use will depend on what kind of project you’re working on, whether it is for deck framing, joists, railings, boards, balusters, etc.
#3. Thread Size
For the uninitiated, a screw thread is the helical structure that wraps around the cylindrical shape of the screw.
Deck screws usually have a coarser thread than other screws.
They usually don’t have a number to indicate size as the coarser thread already indicates that the threads on the screws are farther apart than usual.
Screws that are rated for woodwork usually have similar thread sizes.
Example of Determining Deck Screw Size
The deck screw size you pick depends on what part of the deck you need screws for.
We’re talking mainly about: framing and joists, decking, railings, and balusters.
For example, when you’re working on the deck framing, I always recommend that screws be at least ½-inch in diameter in order to be able to support the weight of the deck.
Anything smaller could make your deck framing on the side of unstable.
Your screw length can be determined by the thickness of the wood you’re working with, as the screw needs to penetrate halfway through the second wood member it’s being attached to.
Say for example, you’re securing a 2×6 rim joist to a 4×4 post base, you will typically need a 4-inch screw.
Working with 5/4 deck board (i.e. 1.25-inch thick lumber), means you’ll end up with a planed and finished thickness of about 1.063 inches.
So this means you’ll want to secure these pieces with a 2-inch screw if going into 6-inch joists.
In the second example, you don’t need to go half way through the joist, but at least the same distance as the deck board thickness.
Depending on your design, you may inevitably have hard-to-reach spots that require a special guide, such as jig – you can use our Kreg jig screw chart to help determine proper sizing for when using their Deck Jig.
Deck Screw Size Chart
| Gauge | Shank-hole size (in) | Pilot-hole size (in) | Lengths (in) |
8 | 5/32 | 7/64 | 1/2 – 2 |
9 | 11/64 | 1/8 | 3/4 – 3 |
10 | 3/16 | 1/8 | 3/4 – 4 |
12 | 7/32 | 9/64 | 3/4 – 4 1/2 |
14 | 1/4 | 5/32 | 1 – 6 |
| 3/8″ | 3-6 |
FAQs
What are the Types of Deck Screws Available?
There are many types of deck screws available in the market, depending on your requirements.
These include:
- Structural deck screws
- Hidden deck screws – for use with grooved deck boards; used with clips to create perfect spacing, drainage and ventilation and super clean look.
- Ledger style screws – often flat-head screws for a flush finish, corrosive resistant and self-drilling (no pre-drilling required!)
- Stainless deck screws
- Composite deck screws
Is a Deck Screw Same as a Structural Screw?
Deck screws and structural (or construction) screws fall under the same category of wood screws and size charts – but have their own unique features.
The major difference between deck screws and structural screws is the size.
Deck screws are longer than regular screws, and construction screws and lag screws are longer than deck screws.
The bigger size of construction screws means they can be used in larger projects and also tend to be more durable.
Another difference between deck screws and construction screws is the material they are made of.
Deck screws are generally made of stainless steel or copper for their anti-corrosive properties, which makes them more durable, especially in outdoor environments, while structural screws have an additional coating (usually zinc) to give them extra protection from rust and are hardened with heat to provide extra strength.
Should I Use #8 or #10 Screws for Decking?
The deck board is the part of the deck that takes the majority of direct pressure and abuse, so naturally, it’s important that it is secure and well-fitted.
However, in the #8 vs #10 decision, a bigger screw doesn’t necessarily mean a stronger hold.
Try using a #8 screw when affixing your deck board as a screw with a higher diameter can split the wooden plank (deck board).
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When embarking on a home renovation or outdoor project, pay close attention to the tools and equipment you use.
That’s why we also provide charts for general wood screws and bolt sizes.
The wrong materials or sizes can drastically affect your project and peace of mind.
This applies to the screws you use, especially when working on decks.
To summarize, deck screws are specially-designed screws that have been manufactured to meet the high demands of outdoor decking.
While screws may seem indistinguishable, please remember that they are not interchangeable and that specific screws and screw sizes exist for different projects.
I hope this article answers your questions about deck screw sizes, like what size screws to use for deck framing or what type of deck screw best suits your needs, and gives you added confidence the next time you walk into a hardware store.
While I’ve attempted to cover the basics of deck screws in this article, make sure to consult with construction professionals and experts as well to ensure the success of your decking project.
