As supervisor of the UCI carpenter shop, Bill Mitchell remodels labs, classrooms and offices; building playhouses isn’t part of his job description. So what was he doing this summer, hammering away on one just outside his office?

Mitchell and a half-dozen co-workers in facilities management recently donated their free time and trade skills to Project Playhouse, a benefit for HomeAid Orange County’s shelter development program. They invested hundreds of hours, working on weekends, evenings and even coming in as early as 4 a.m., to complete their playhouse.

“Participating in Project Playhouse gives us the opportunity to use our skills for a good cause, and allows us to showcase our talents,” Mitchell says.

Like other custom playhouses to be auctioned in the annual fundraiser, theirs is no ordinary plywood hangout. Rather, it’s a Cape Cod charmer on a mini scale, complete with dormer windows, porch swing, inside loft and Dutch door. Thanks to donations from individuals and local businesses, the crew has decked out the 8-by-10-foot interior with a rock fireplace (featuring a faux electric fire), a flat-screen TV, DVD, Xbox, children’s furniture, a tiny kitchen – even teddy bears and teacups.

“When I was a kid, I had a tree house, but it was nothing like this,” Mitchell says.

All of the elaborate themed playhouses, including Facilities management’s “Fun at the Cape,” will be sold at a public auction. The playhouses usually fetch between $15,000 and $40,000.

Mitchell, a Costa Mesa resident, first participated in Project Playhouse three years ago, when he worked for the Orange County Sheriff’s Office. He taught inmates at the James A. Musick Facility in Irvine basic construction skills so they could help build a playhouse; their entry last year was a quaint Victorian with matching doghouse.

When he came to UCI about a year ago, Mitchell was determined to continue the tradition. He pitched the idea to his supervisors in facilities management, and they loved it.

“This is a great cause. I’d stick to it even if I had to build the playhouse myself,” he says. “But with the backing of facilities management, this project took off.”

It took his team of UCI volunteers scarcely a month to go from framing to the final coat of paint. Their cottage will be displayed with the other playhouses at Fashion Island, Newport Beach, Sept. 9-Oct. 14. All playhouses can be viewed through their front doors from 11 a.m. to 5 p.m. Saturdays and Sundays for a $5 per person donation, and tours of the playhouse interiors will be available at an open house 11 a.m. to 5 p.m. Saturday, Sept. 9, for a $15 donation.

The auction will be held at 5:30 p.m. Saturday, Oct. 14, with proceeds benefiting HomeAid, which builds and renovates temporary shelters for Orange County residents who find themselves homeless due to sudden job loss, catastrophic illness, spousal desertion or domestic violence.