Yes, and in some cases, frozen ground may improve the digging process for footings due to sturdier conditions. It’s easier than working in muddy conditions, which are more common in the spring. Contractors may use machinery that makes this step a breeze, so harder ground shouldn’t affect the building process.

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. 

Before installing a deck, you must build a base for the deck to rest upon, often made of compacted soil or gravel. While gravel is an optional material, it helps with drainage. Some contractors also recommend installing a weed control membrane, which helps provide a solid foundation for the frame. In the case of an elevated deck, a pro will often lay down a concrete slab as a foundation. 

Materials for a second-story deck must be weather- and rot-resistant, though the specific choices will largely be determined by your budget and style preference. Pressure-treated wood is on the lower end of the price scale, but it can be customized and stained the way you like it. Composite, on the other hand, is pricier for installation and has fewer options for customization, but you’ll save money and time in the long run because it requires little maintenance.