How to choose joist hangers for a deck
When building a deck, you'll have a number of joist hanger options—galvanized, triple galvanized, coated and stainless—all at a wide range of prices. Which one is best?
If you live in a coastal area (near salt water), you don't have a choice—the building codes require stainless steel hangers, plates and fasteners. But if you live inland, you have more options. Most codes allow you to use hot-dipped galvanized (sometimes called triple-zinc) hardware (see Photo 1).
However, if you want to take a step up in corrosion protection, you can buy Gold Coat galvanized hardware that's been treated with an inert barrier coating (see Photo 2). It costs three times more than traditional hot-dipped hardware, but lasts longer (for more info, visit uspconnectors.com). Or you can increase the life of triple zinc hardware by installing corrosion-resistant flashing between the wood and the hot-dipped galvanized hardware (Photo 3). Grace Vycor Deck Protector (graceathome.com) and Protecto Deck Flashing are two brands; they're available from your lumber supplier. It's ugly, so you might not like it on a raised deck where you can view the deck from beneath.
Before you decide on hardware, consider this. The newer arsenic-free treated lumber hasn't been in the field long enough for anyone to know how long hot-dipped hardware will last. Since the hardware is the least costly part of your deck, you might want to hedge your bets by upgrading to stainless steel even though it's seven times more expensive. That way, you'll never have to replace hardware. This advice is especially germane for decks sporting super-long-lasting composite materials. There's a real chance the decking materials will outlive all the hardware.
Note: Never mix fasteners. Use stainless nails with stainless hardware, and galvanized fasteners with galvanized hardware.