When you’re investing in a new deck, exterior screw coatings are more important than you might think. Unless you’re a contractor, you can probably count on one hand the number of times this subject crossed your mind. But when you build outdoors, the fasteners you use can have an outsized impact.
We’ve all seen gorgeous wooden decks ruined by rust stains. Although corrosion can seem like an aesthetic problem, it also leads to structural issues. Keeping corrosion at bay is one of the most important ways to safeguard your outdoor building projects.
Screw coatings protect fasteners from the effects of weather exposure by sealing off the metal from the elements. In fact, almost all screws intended for use outdoors have some kind of coating or are made from corrosion-resistant materials like stainless steel. There are lots of options out there, and we’re here to help you cut through the noise.
Let’s get down to the core of exterior screw coatings and find the best fastener for you!
Most screws manufactured for outdoor use are made from steel. It’s not corrosion-resistant on its own, but with the right combination of alloys and coatings, it can stand the test of time. Primarily, you’ll see either stainless or coated steel fasteners for exterior applications.
Stainless steel screws are popular near water and coastal areas because they’re naturally rust-resistant. By definition, stainless-steel screws must contain a minimum of 10.5% chromium. This addition reacts with the oxygen in the air to create a protective barrier against moisture. If the layer is damaged by environmental or mechanical factors, it reforms over time, keeping screws protected.
Grip-Rite® PrimeGuard MAX® screws are manufactured from 305 and 316-grade stainless steel. These grades all contain between 18 to 30% chromium and 6 to 20% nickel, which provide superior corrosion resistant properties. While each is resistant to moisture, only 316 (marine grade) is specified for use near coastal regions due to the inclusion of molybdenum in the alloy.
Coated steel fasteners are a more economical choice for outdoor construction. The types of coatings vary in thickness and effectiveness across the industry. Instead of more costly stainless steel, exterior-coated screws use common black steel, which is then treated to resist rust. As long as the coating isn’t compromised, the screws won’t rust or corrode over the life of the structure.
To ensure that fasteners live up to their claims, the American Society for Testing and Materials (ASTM International) sets baseline standards they must meet. ASTM testing protocols and specifications push the limits of what these exterior screws claim. The Neutral Salt Spray Test subjects fasteners from 24 to over 1000 hours of exposure to 5% sodium chloride mist.
When choosing fasteners for projects near the coast, it’s important to look for the ASTM B117 hour rating which indicates the number of hours of continuous corrosion testing prior to the appearance of red rust.
Exterior screw coatings fall into several categories based on the formula used. Each offers a different level of protection from the elements and features that make them better in certain applications.
Zinc is commonly used to coat screws intended for exterior use through a process called galvanization. Whether through electro-plating or hot dipping, protective layers of zinc are deposited on the steel to form a barrier on the surface.
Electrogalvanized screws have a thinner layer and are a more economical option than hot-dipped fasteners. Because they have a thinner layer, though, they’re more likely to rust over time. Hot dipping leaves a thicker layer that resists corrosion longer but is often uneven, especially in threaded fasteners.
Polymer-based epoxy is a common coating used for deck screws because it protects against corrosion evenly. Typically the underlying metal is electrogalvanized prior to coating for an added layer of protection. Barring any damage to the coating during installation, you can expect these screws to last for the usable life of your project.
One of the primary benefits of this type of coating is the ability to match the color of your project. Different manufacturers use different formulas, and some are more effective than others. Put through their paces, Grip-Rite® deck screws outperform other brands consistently.
At Grip-Rite®, we know you need fasteners that get the job done right. We’ve engineered several exterior screw coatings that guarantee corrosion resistance and are routinely tested to ensure our specifications are met or exceeded.
PrimeGuard® is our proprietary coating, consisting of an electroplated zinc base layer and epoxy resin top coat. Guaranteed for up to 10 years, the coating provides robust protection against corrosion. Ideal for projects involving treated wood, it offers quality and value.
In the ASTM B117 Neutral Salt Spray test, they endure a minimum of 750 hours of exposure with no more than 5% red rust.
PrimeGuard PLUS® uses a similar coating process to PrimeGuard® but undergoes a more extensive testing process. In the ASTM B117 Neutral Salt Spray test, they endure a minimum of 1000 hours of exposure with no more than 5% red rust.
If you’re working on outdoor projects like fencing, siding, or decking, you can count on PrimeGuard PLUS® coated screws to last the life of your project.
When nothing but the most robust protective coating will do, PrimeGuard® Nano is the clear choice. Built on an electroplated zinc base layer, the organic top coats provide an impenetrable coating that stands the test of time. Installed properly, they’re guaranteed to last the lifetime of your project. They work well in wood-to-wood and treated wood building projects but aren’t rated for use with cedar or around pools.
In the ASTM B117 Neutral Salt Spray test, they endure a minimum of 1000 hours of exposure with no more than 5% red rust.
Choosing the right fasteners for your project shouldn’t be a hard decision. Grip-Rite® makes it easy by offering a full range of outdoor screws with non-corrosive properties to meet your needs. Whether you’re building a dock on the coast or a deck in the mountains, our PrimeGuard® fasteners have you covered. Check out our full line of exterior screws before speccing out your next project.
