What's the Difference: Deck screws
When choosing your deck screws, keep in mind where they're being used and how long you need them to last
When is the best deck screw on the market a waste of money? Darin Lawrence, technical manager for McFeely’s Square Drive Screws (800-443-7937), says that it’s when you need a fastener that’s only pretty good. Lawrence is happy to recommend galvanized screws over stainless-steel fasteners for a pressure-treated pine deck that’s constructed well away from the coast. But put that same deck on the beach, or use either redwood or cedar decking, and those expensive stainless-steel fasteners become the ideal choice.
Choosing the most appropriate deck screws depends on where they will be used and how long you expect them to last. Choices basically fall into two groups: stainless steel and everything else.
For corrosion resistance, stainless steel is the best of the lot. But these fasteners are expensive. Building-supply dealers and catalogs may offer as many as five different types of stainless-steel screws. Basic stainless steel—sold as type 302, 303, 304 or 305—contains 18% chromium and 8% nickel plus other alloys. These screws are often called “300 series” stainless steels, or simply “18/8.” The differences among them, Lawrence says, amount to relatively minor variations in alloys. The chromium-nickel content is the same in all of them.
When used on a noncoastal deck, an 18/8 screw is essentially a lifetime fastener, meaning it will last as long as a top-quality deck board, such as ipé. But in a salty environment, the best bet is a 316 stainless-steel screw, which has a significant amount of molybdenum added to increase corrosion resistance and strength. Of course, this higher corrosion protection comes at a higher cost; at McFeely’s, for instance, 316-grade #10 by 3-in. screws cost about 65% more than the same size screws in an 18/8 grade.
Lawrence says many people mistakenly believe that stainless steel is much harder than conventional steel. Not true. In fact, stainless-steel…