Will Deck Screws Rust? How to Prevent Fastener Rusting


Some say that rust is like cancer to your outdoor projects. Rust occurs as a reaction of iron with oxygen, causing an orange-colored film to spread on screws, eventually having the potential for the screw to disintegrate entirely. When building your deck, you want to make sure that it can last a long time without having to worry about corrosion.

Deck screws can rust, depending on the type of screws you use. Stainless steel screws are rust-resistant both on the outside and inside. Galvanized and Zinc screws are coated with a rust-resistant layer of zinc, but the outside coating can eventually wear off.

If you walk in any hardware store, you will see that there are hundreds of screws to choose from. A number of screws will work well for your outdoor project, but what screws will be more likely to rust? This article will look at the best screws to use for an outdoor project and will give you some ways to prevent fastener rusting.

How Do Deck Screws Rust?

Rust is a chemical compound, and its scientific name is iron oxide. Rust occurs when iron (or any of its alloys, including steel) is exposed to oxygen and water (this can be moisture in the air). The process of rusting will start when that relationship (the relationship between iron and oxygen) is initiated and will cause the iron to corrode.

The screw can also eventually disintegrate. A few things that can speed up the process of rusting is water and salt.

Reading about the process of rusting may be disheartening when thinking about what screws to buy. The majority of screws are made of metal, and a lot of locations have either rain or moisture in the air. It seems like an impossible problem to solve, but not to worry – keep reading for information on the most popular screws to use when trying to prevent rust.

What Screws Should I Buy for My Deck?

The first step to rust prevention is buying the right screws. Even though a wide variety of screws are made to be resistant to rust, some screws offer more protection than others. Certain screws are also stronger and may last longer, but the cost will also be greater. Let’s look at the different options.

Screw TypeCostRust Resistance
Zinc or PhosphateLowLow
Galvanized
(mechanically)
LowLow – Medium
Galvanized
(hot dipped)
LowMedium
Stainless SteelMediumHigh

Galvanized Screws

Galvanized screws are the first screws we will be talking about today that are resistant to rust. These screws are resistant to corrosion because they are coated with a thick layer of zinc. This layer of zinc prevents the iron from reacting with the oxygen and water in the air, therefore stopping the problem before it even begins.

Overall, galvanized screws are the most popular because they are both corrosion-resistant and affordable.

GalvanizedOpens in a new tab. screws are the least expensive screws we are discussing today, which makes them a nice option. The downside of these screws though, is that only the outer coat of the screw is rust-resistant. The insideOpens in a new tab. of the screw is made of black steel, which is very susceptible to corrosion and rusting.

Even if there is one small hole in the zinc coating, the entire screw can eventually disintegrate, but even then, it may take a while.

Lastly, there are two types of galvanized screws. There are hot-dipped, and mechanically galvanized screws. Hot-dipped galvanized screws have the thickest coating, consisting of both iron and zinc. Mechanically galvanized screws have a thinner coating consisting only of zinc.

In regards to being resistant to corrosion, hot-dipped are more resistant because of their thicker coating.

Stainless Steel Screws

The stainless steel screws cost about twice as much as the galvanized screws, but they offer more protection from rust. Many people use stainless screws for decks because the screw is not just coated with rust-resistant material, but is made entirely of it.

These screws don’t have a coating that may or may not wear down, and for this reason, they will last longer than galvanized screws.

There are a few different grades of stainless steel screws that are important to look at when thinking about rust prevention. 304 and 305 grades are widely available, but the 305 grade offers slightly greater resistance to corrosion. The 316 grade is for extreme environments, such as for decks near the sea. This grade offers maximum corrosion resistance.

Check out this video for some more info on choosing the proper screws for your projects:

How Do I Prevent Fastener Rusting?

There are a few extra ways to prevent fastener rusting that you can do on top of already having suitable screws. Let’s look at a few.

Buy the Right Screws

This is the easiest and biggest way to prevent rusting – buy the right screws at the start of your project. If you go for the more expensive option like stainless steel, it is likely you won’t have to resort to other options to prevent rusting. Buying the right screws will allow for a lasting product that won’t rust.

Keep Your Deck Screws Dry

The biggest factor that will quicken the process of rusting is water. If possible, when building your deck, place your deck screws in areas that are the least likely to get wet. Another possible option to help implement this is deck flashing tape.

This is a type of adhesive tape that you can put over your screws to keep the moisture out. The tape also prevents the surrounding wood from splitting.

Use Mineral Oil or Paint

While these are both temporary prevention methods, these can still help prevent rust. Mineral oil can work as a rust inhibitor. You can take a brush and coat your nails with mineral oil for some extra protection.

Paint is also an effective (temporary) rust inhibitor since it blocks the reaction of iron and oxygen, therefore prevents rusting.

Do GRK Screws Rust?

GRK screws are probably one of the most popular brands to date. While these screws are more expensive, they are strong, and, like any other brand, if you choose the correct screw, they will be resistant to rust. GRK has two grades of stainless steel screws to choose from and a wide variety of multi-purpose screws.

Check out the different options available and prices for each here: GRK ScrewsOpens in a new tab. (link to Amazon).

Do Zinc Screws Rust?

While zinc screws are coated to be rust-resistant, they are not recommended for outdoor use. Zinc screws are electroplated galvanized screws, meaning they have a thinner layer of zinc compared to galvanized screws. This thinner layer makes them a bit more susceptible to corrosion.

Zinc screws are also made to be more aesthetically pleasing (they have a bright silver finish), which is why they are used for indoor projects.

Conclusion

If you pick the right screws for your project, you will not have problems with corrosion. Stainless steel and galvanized screws are the best options if you want to prevent rust. You can also use brass-plated and copper-plated screws (they are also resistant to rust), but keep in mind that they are not as strong as steel screws.

If you want additional protection, place screws in areas where they are less likely to get wet. Additionally, you can coat screws with either mineral oil or paint to prevent further rusting.

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Robert Sampson

I'm Robert Sampson and I live in Colorado where I spend a lot of time in the backyard with my family either grilling, playing games and sports, or working on a project to make our backyard a better place to be.

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