It's midnight when the ad for a hardwood basketball floor appears on Craigslist. Joel Allen, 30, has been hitting the Refresh button for hours searching for something, anything, of value.

Now the moment he's been waiting for has arrived.

Though it's streaked with red lines, the floor's a real gem. It's free but could easily go for $2,000 at $11-$12 per square foot. The owner is desperate to get rid of it, and Allen's convinced it's all he needs to finish his project.

Allen isn't building a house. He's building a secret cabin deep in the woods of Whistler, British Columbia.

No one knows the egg-shaped treehouse exists, and Joel likes it that way. The treehouse is being built on "crown," or government land without a permit, and while he doubts this will get him arrested, he'd prefer not to chance it.

Whistler is a rich person's playground just two hours north of Vancouver. It has world-class skiing, mountain climbing and golfing. But it's also a place where low-income workers increasingly can't afford to live.

This is why Allen is building the cabin. He wants a "secret little loft" to call his own.

Back in 2006, Allen, then 26, quit his day job as a software developer to pursue his dream of an early retirement. He ended up building a beautiful egg-shaped treehouse ("The Hemloft") instead, using $10,000 worth of free materials he found on Craigslist.

In an interview, the self-taught carpenter explained how he did it:

"I wanted to build something beautiful"

During the first season of building the treehouse in 2009, Allen spent $6,500 on the roof and frame.

"Nothing was flat, so I knew the finishing stages would be more expensive," he said. "After the first season, I could hardly afford to continue because it was so pricey. The place sat in a holding pattern for nearly two years."

But searching for a couch on Craigslist's free section got Allen thinking about what else he might find there. Soon he was repurposing valuable, broken materials like a double sliding glass door (valued at $400) into windows, and an ash hardwood floor (valued at $7 per square foot; $1,500 total) into a cabinet.

"I started trolling, pressing Refresh twice a minute, and getting really competitive about it. A lot of people in Vancouver were getting rid of amazing things, but you had to act fast," he said.

Part of Allen's goal was not to build something off the grid "in ramshackle fashion," like so many of the alternative homes he'd seen in Whistler, left to desecration.

"I wanted to build something beautiful with good materials," he said. "I wanted a place that was nice and though it was on government land, it felt like my big back yard."

As a carpenter, Allen could easily assess an item's value based on the prices he'd seen in hardware stores, then decide what was worth keeping or tossing out.

The Hemloft was slowly coming together, but Allen's Craiglist habit was spiraling out of control.

No room to breathe

Things got to the point where Allen could hardly fit into his apartment, let alone his bed.

His girlfriend Heidi, who'd been helping Allen build the loft, was sympathetic. But his landlord, a former carpenter himself, was beginning to catch on and Allen didn't like it.

"What's going on in here?" the landlord asked one night, surveying the wooden slats and glass strewn about.

Allen came clean and confessed he was building a secret cabin that might also be illegal.

"That's it?" the older man replied. "You need a place to store all this stuff."

Allen felt a wave of relief when the landlord revealed he'd had the same "itch" years ago.

"He actually helped a lot with storage, which was a lifesaver. He knew where I was coming from."

The ultimate find

The obsession and work on Hemloft were nearing an end by July 2010. However, Allen was bent on owning the floor he'd seen online.

By posing as another caller ("I said I was Rudy"), Allen arranged to pick it up in two hour-long trips back and forth from Whistler.

"I finally got there and the owner was like, 'Take this now because the moving truck's coming.' I filled the Suburban right up to the top because it had extra padding and was so bulky. I got back home at 1 a.m., unloaded until 3 a.m., then had to be back at 6 a.m. to get the last load just as the truck arrived. (Heidi and I) hardly had a place to sleep after that," he said.

August 2010 marked the completion of the Hemloft—while the floor sat gathering dust at Allen's apartment.

"It was a major stress in my life because I was trying to sell it, and had no place to keep or move it."

So what finally became of the floor and Hemoft?

Allen eventually made $2,000 by selling the floor to a lawyer who was building a home of her own in Vancouver.

The same can't be said of the Hemloft, which remains intact, untouched by authorities, and cool as ever.

"I just needed the right person who could appreciate the look," he said of the floor. Hemloft is another story.