The grilling season is well underway, and one of the hottest trends is bringing the kitchen outdoors, literally.

Once thought practical only in warmer climates, outdoor kitchens in Northern homes are heating up. They're now part of the planning stage in some new construction, with built-in grills that spew out more than 50,000 BTUs and cost $7,000 and up ... outdoor-ready pizza ovens for $12,000 ... dishwashers that cost $4,000.

Trevarrow, a Michigan-based distributor of Wolf and Sub-Zero appliances including ones for outdoors, has seen double-digit growth in its outdoor appliances business.

While outdoor kitchens once were considered only for warmer climates, such as Arizona, they're now becoming more practical Up North. "Ideally, you can get eight to nine months out of it," said Don Cooper, Trevarrow's corporate sales manager. It's easy to deal with the winter cold using outdoor heaters.

Outdoor kitchens are now rivaling indoor kitchens, according to Russ Faulk, vice president of design and marketing for Kalamazoo Outdoor Gourmet.

"We are the upper end of the upper end," Faulk said. "Our average outdoor kitchen order is in the $30,000 to $50,000 range in the appliances and cabinetry."

From top: A pizza oven produces homemade meals without heating up the indoors. A Sub-Zero mini fridge is part of this outdoor set-up. Outdoor appliances are a growing business.

Outdoor kitchens can include cooking areas with refrigerators and icemakers, designed and built for outdoor use, that cost several thousand dollars each. There also are shiny, built-in stainless-steel kitchen sinks and even dishwashers — all designed to be weather-resistant.

"It's been growing for the last five, six years," said Dominick Tringali, staff architect for Moceri, a custom home builder.

A Moceri-built home undergoing reconstruction has at least $35,000 in appliances, including a stone island with a Sub-Zero built-in dishwasher, storage drawer and a warming drawer, and another base with a refrigerator, cupboard storage and a Wolf grill.

"There's more interest in improving outdoor space," Frank Moceri said. "People are finding a better investment in outdoor space and something they can enjoy after the kids leave home."

What you spend depends on what you want or need. Builders and designers peg pricing from $15,000 to $50,000, depending on size, materials and appliances.

The Hearth, Patio and Barbecue Association puts outdoor rooms in the leisure lifestyle category and says it's a $6.2 billion industry.

"The options are enormous and for all weather," said spokeswoman Leslie Wheeler. "You can custom-make it to fit your lifestyle. If pizza is your favorite, plan on a pizza oven."