Galvanized screws – Why do you need to care?

The right screws equal long-lasting exterior wood projects. That’s why it’s important to know which screw makes the most sense for your particular project to keep it sturdy and secure long-term.

Braving the elements

Pressure treated wood is your best friend for most outdoor projects, because it’s best able to weather the elements. When it comes to screws, use building-code approved, corrosion-resistant fasteners and connectors suitable for use in pressure-treated wood. Viance, who manufactures preservatives for pressure treated wood, recommends hot-dipped galvanized or stainless steel fasteners and connectors, specifically G185 hot-dipped galvanized connectors for exterior use. For coastal installations, we recommend code-approved stainless steel.

Some preservatives can be corrosive to screws. Non-metallic and micronized copper preservatives are less corrosive to connectors and fasteners and can be used in direct contact with aluminum products, even in continuously wet applications. This is not the case with all preservatives. Check the end tags of treated wood to learn about the preservative used. You can also contact with the preservative company to see what types of fasteners and connectors they recommend.

Iron Rot

“We are seeing more incidence of a condition we call iron rot where fasteners that are not corrosion proof can cause wood degradation,” said Ed List from C.M. Tucker Lumber Co. in Pageland, SC. “As the oxidation of rusting occurs it creates a low molarity of acid that can cause the wood to dissolve and look charred.” 

Photo indicates wood failure occurring around the fastener location as a result of iron rot corrosion

List added, “The importance of using stainless steel and appropriately hot dipped galvanized fasteners are so important when building outdoor structures.”

When we’re talking about decking

The corrosiveness of the screws you use is a real concern because on top of typical wear and tear from use, fasteners will be exposed to the elements. We won’t get deep into the weeds with the chemistry behind it all, but, suffice it to say, you need to become at least a little acquainted with what to look for (or avoid) when you’re at the hardware store buying screws for your outdoor project.

The bottom line

If you’re building an outdoor project with pressure treated Southern Yellow Pine, used galvanized steel to help secure it. If you need help finding it, ask a specialist at your hardware store. They should be able to direct you to a screw that will help keep your deck project secure for years of enjoyment.