You can build an outdoor kitchen on a deck, but you should choose composite decking since it's more heat-resistant. Metal deck materials like steel and aluminum are also good choices because they're less flammable than wood. You should also consider the weight of the kitchen—make sure your deck can support it and any appliances you plan to use. You should consult a structural engineer to confirm exactly how much weight your deck can safely support when building an outdoor kitchen. 

When deciding if you should use 2x6 or 2x8 deck joists, consider the size of the deck, joist spacing, and materials. Larger decks, larger-spaced joists, and weaker wood all require more support, meaning they need larger joists. For example, 2x8 redwood joists spaced 16 inches apart can only safely span up to 10 feet and 7 inches. On the other hand, 2x10 southern pine joists spaced 12 inches apart can be as big as 16 feet and 2 inches. If you aren’t sure what size joist is best for your project, speak with your deck builder.

Deck boards should be spaced no more than three-eighths of an inch apart. This is enough space to allow water and small debris to pass through without collecting on the surface, but not enough to create a tripping hazard. Certain materials, like pressure-treated wood, shrink over time, so they may need less space at installation.

Because adding a deck will yield a higher property value, you may have higher insurance costs. It’s important to follow the codes and regulations set by your local and state governments, so your insurance rates can be properly calculated. You may need an insurance revaluation after your deck is completed. The best course of action is to speak with an insurance professional to understand how adding a deck will impact your home’s insurance costs before you begin.