KIAWAH ISLAND — One of this island’s greatest new living spaces doesn’t have heating or air conditioning or a television.

In fact, the building known as the Creek House barely has any walls at all.

This special living and dining area is the opposite of a formal historic house. It’s basically a glorified picnic shelter, but this new work of architecture also has an important preservation role.

That’s because the Creek House is built near — and serves as a sort of relief valve for — the Vanderhorst Mansion, an 18th-century home renovated and expanded for use as a family compound in the early 1990s.

As the family’s five siblings have had larger families of their own, their gatherings placed more pressure on the historic house, says family member Scott Parker, who also is a partner in the landscape architecture and town planning firm DesignWorks.

Both the old and new houses may be seen by the public Saturday, when they’re on tour to benefit the Charleston Symphony Orchestra League Inc.

The family hired architect Reggie Gibson for the project, which is built in the woods, screened from the historic mansion.

“We wanted the integrity of the main house to stay intact and we didn’t want anything new to compete with it,” Parker says. “That opened up more freedom to do things that didn’t necessarily have an architectural relationship with the main structure.”

The L-shaped Creek House is at once simple and elegant, with wooden columns supporting two intersecting sheds, including one whose roof rises as it gets closer to the marsh. There’s a bar and bathroom and room for a Ping-Pong table at one end, and a kitchen and dining area on the other, with a seating area and fireplace separating the two.

Gibson says the Creek House was sited based on archaeological surveys and to be close to, but not really visible from, the historic house.

It’s also a bit pulled back from the water and nestled into some large oaks, so it wouldn’t pop out to those kayaking by.

“There was an old kitchen building that was there. We built the new building around the old kitchen building,” he says. “It focuses on the marsh but there’s an old fire pit and the old foundations of the building are there. ... It sort of just started from the ruins that were there.”

The water side resembles a giant, screened porch, while there’s more of a substantive wall on the back, where the house meets the woods.

Outside, the old kitchen foundation was rebuilt gently, using bricks on the site and proper preservation techniques, Gibson says. Two of the bars inside were made from a big oak limb that had fallen on the site.

“Ideally, the wood will just go to gray. The copper will go to green,” he says. “You don’t really see it much now, but ideally, it will just become more and more invisible.”

The program did expand to include a bathroom and outdoor showers. “It’s kind of an outhouse but it’s attached,” Gibson says. Parker says since the Creek House was finished a few years ago, he spends more time there than in the main house.

“The main house becomes the place to sleep,” he says. “The majority of the time is in the Creek House or outside. It’s been magical. I can’t think of one thing I’d change.”

Reach Robert Behre at 937-5771.