Some tiny homes seem so ideal that it’s tempting to avoid changing them, even when life demands otherwise. That’s how Pam Austin felt when her family began outgrowing the 450-square-foot log cabin she owns on Guemes Island, off the coast of Washington.

In 2000, Ms. Austin and her now ex-husband bought the little house, which sits on a beachfront lot, as a getaway from their primary home in Seattle. At the time, Ms. Austin, 72, said, “it was charming, but in bad shape” — overrun by mice and riddled with mildew.

The structure had been built on another island in the early 20th century, neighbors told her, and in the 1940s it was dismantled, floated and reassembled at its present site. More than half a century later, it was in such disrepair that “the people who owned it before us wouldn’t even stay in the cabin,” Ms. Austin said. “They’d just pitch their tents in front.”

In the years that followed, she brought the one-room cabin back from the brink with help from family and friends. They cleaned it up, evicted the mice and repaired the chinking between the logs. Simplicity was the guiding principle. The one-room cabin has a small, bare-bones kitchen, a stone fireplace, a wood-burning stove and a built-in nook with a mattress for sleeping — and that seemed like enough.

“It’s just a really easy place where the kids could run in with sandy feet,” Ms. Austin said. “There’s nothing precious.”