Deck Screws

Building Your outdoor deck and deciding on a Deck Screw

The decision to start your deck project

So, like last spring, you sip your morning coffee, look at your yard through winter-grimed patio doors and say, "Yes! This is the year I build the deck of my dreams". Or, maybe you're squinting at a tangle of soggy planks with protruding rusty nails and thinking "Did someone wreck a fishing boat next to the pool?". Then you realize that this was last year's deck of your dreams.

Let's say that this is the spring where you get your outdoor deck project off the ground.

Where are the fasteners in your plans?

Whether building or rebuilding a wooden deck, there's one thing you are going to need in large quantities BESIDES lumber, and that's fasteners. And if you've ever lived with a wooden deck that was nailed together you've probably looked at those creaking, buckling loose planks and wished someone had used deck screws instead.

Compared to the cost of the entire project, fasteners represent a small part of your total budget, so you are going to see a great return on your investment if you decide to go with a deck screw. And the nature of a deck actually demands that you go with a superior fastening product - which a nail is not.

So, why a Deck Screw?

First, consider what a deck is: an outdoor structure that has to bear constantly shifting loads. Even your garden shed only has to worry about snow on its roof and hiding your lawnmower.

But your deck has to support your kids running over it, your in-laws lounging on it, and your BBQ buddies re-enacting their famous high-school football plays. And today's decks can be complex structures as they have a decorative role in your back yard. With their swooping staircases, fancy lattice work and multi-level designs, today's decks aren't the brown wooden boxes of yesteryear.

All of this means that your deck really needs to hold itself together. You'll be investing time and money in designing and building a solid, attractive deck that your family and friends will enjoy in safety. Just one look at this frightening case: "Catastrophic Residential Deck Collapse". This sort of tells us that we really should be thinking about what is going to hold everything together. By the way, another big lesson from this article: do not NAIL your deck to the supporting structure. Instead, use big, solid fasteners, like lag screws!

One serious screw...

Let's look at the advantages of a purpose-built deck screw. We'll start with its physical design: the head, its drive, then the shank with its threading and point.

The shape of a Bugle vs. Regular Countersunk Head

The deck screw's head should have a "bugle" design, a flared, counter-sunk profile which presents the same flat top surface as a flat countersunk wood screw, but with a larger load-bearing surface against the soft planks. What does that give you? Well, if you look closely, you'll see the "bugle" head shape flares out to lay against the board. This shape means the head resists the tendency to work its way into the wood after it's been set.

Another consideration is the drive, and for fast and reliable assembly, you don't want to go with a slot drive. A deck screw with a Phillips drive has one advantage: it's a reliable type of drive commonly in use in the USA. Yes, everyone's toolbox is chockfull of screwdrivers and power-driver bits for Phillips drives.

Growing in popularity in the USA (as it always has been popular in Canada) is the square drive screw. Why? Because when you use a square drive bit you'll notice its unique ability: the tapered profile of the driver bit actually wedges into the drive and holds the screw in place for you at any angle, even when pointing down to drive into a floorboard. In addition, the square drive arguably suffers much less from stripping or "camming-out". You can imagine what these qualities do for building efficiency!

Nails Gone Wild. Ouch.

Next, we turn our attention to the deck screw's shank. This baby is designed for strength and speed. The aggressive point and deep, sharp threads are designed to quickly bite into the wood and bury itself quickly and solidly. Seen edge on, the deep threading is actually razor-thin and sharp. Imagine how wood retains the screw in place -- and then imagine a nail doing the same job. The shank is actually partially threaded and tapered so that the threads bore quickly. But by the time the screw is set and buried, its head is anchored to a full-metal, unthreaded shank. It's not going anywhere.

Now let's go back to thinking about your BBQ buddies re-enacting their famous Championship QB Surprise Sack of '95 on those planks. Not a place for an errant nail.

Material world

We've saved the real issue for last: material and coating. This is what sets this fastener apart as a true all-weather fastener. You might be looking at a screw in your hardware store and thinking, "looks like a deck screw to me". But you'd have to read the fine print to know for sure, because if it doesn't say, "deck screw" then you have to know if it's made with hardened steel... and if its stainless steel... and if its galvanized... and will it stain if there's corrosion...

There's an interesting article on the choices here: Fastener Experts: Explaining Dacrotized Finishes, but let's run through the options:

Choose a stainless steel deck screw if you want incredible longevity. This is the luxury choice, but you might have a concern with their appearance. Those shiny heads are going to be gleaming and winking at you all through the summer unless you paint or stain your deck. This is something to think about if you are using pre-treated wood. On the other hand, that whole "chrome" look of your upscale fastening choice might help get your deck featured on "Pimp My Yard".

You can go for other corrosion-resistant options via coatings. For example, zinc-plated and galvanized screws are more economical than stainless steel, but you'll still have that "shiny screw" concern. But there is something more significant to think about: these screws will react with ACQ treated lumber and actually corrode, staining the wood and even raising health concerns from the leached chemicals.

The aforementioned problem with galvanized screws prompted some public works departments to switch to a "Dacrotized" coated deck screw for use with treated woods, particularly in schools and parks. There's a compelling case for Dacrotized deck screws, and it's hard to imagine even the finest treated lumber outlasting these products. The Dacrotizing process coats the fastener in a tough, impenetrable ceramic coating that keeps the screw stubbornly anchored where it won't corrode or stain. And its gray-drab appearance means it politely disappears into the wood without calling attention to itself.

Of course, you'll have your own considerations to take into account when selecting fasteners for building your deck - your choice of wood, your budget, painting vs staining, etc. I feel that the most versatile and reliable choice is the ceramic-coated Dacrotized deck screw - designed to endure the baking heat, the summer typhoons, the ice storms. And, if you're a pharaoh, the burning hail and the occasional plague of locusts.

Let's build it!

Finished your coffee? You've got a lot more work to do, and a lot more decisions to make. Of course, there are lots of on-line sources available, and a good starting point we can recommend is "how to" videos on YoiuTube.

Enjoy your project. Now, I've got to and let the dog out -- it's spring out there!

First published 2018-06-21 by Aspen Fasteners Inc., updated 2021-01-24