Treehouse Masters - Season 9 (2017)

Pete descends upon western Washington to make a tree house for action and relaxation; with a 55-foot-long bouncy-bridge entryway into a 20-foot-high structure and a zip line that travels through the forest, this tree house generates non-stop thrills.

Pete and his team descend upon Virginia for the first time to bring the tree house revolution to Bella Rose Plantation; drawing on the architectural innovations of Thomas Jefferson, Pete designs a luxurious two-story tree house with colonial columns.

Two retirees get a retreat on their 100-acre Wisconsin farm; Pete builds a barnlike birdhouse with three separate pods - an art studio, an office and a lounge - complete with a screened-in porch and a deck overlooking their stable of alpacas.

Pete is back in Texas to build a sophisticated, sleek-and-chic treehouse in the heart of Dallas; Daryl and the NTS team put treehouse engineering to the ultimate test at Washington State University, proving down-to-the-pound the power of the TAB.

When asked in 2016 what she would do with her winnings, ''America's Got Talent'' Season 11 winner Grace Vanderwaal said she wanted a tree house built by Pete Nelson; the 13-year-old singer-songwriter's wish comes true.

It's the finale in Denali. Pete travels to Alaska to build a mountaineering lodge in the shadow of North America's highest peak, constructing an A-framed masterpiece for the Mt. McKinley Princess Wilderness Lodge with breathtaking views of Denali.