Not all sand castles get washed away by the tide.
"Rammed earth" is a construction method that uses composites of earth (commonly sand-based), clay, gravel and cement to build walls. The process isn't that far from building a sandcastle at the beach. Premade frames are filled with the earth mixture, which is then tightly compressed. When the walls are set, the frames are removed.
It's a building technique that has been around for centuries but can be commonly found in arid climates like the American Southwest.
These homes can be up to 10 percent more expensive to build than traditional homes due to the labor-intensive construction process, according to Sue Turner, owner of a rammed-earth home in Maine. However, these structures are particularly energy-efficient and low-maintenance, thanks to the thickness and sturdiness of the earth walls, making them cost effective long-term.
"You plan for the future when you build a house like this," Turner said.
It's unusual to find a rammed-earth house in New England, but Turner and her husband, Karl Karnaky, felt strongly that their home should be sustainably built.
Homeowners who build rammed-earth houses often have a special interest in minimizing their environmental footprint. They incorporate many energy- and money-saving features into their homes, including solar panels, triple-glazed windows and rainwater barrels.
Finding builders familiar with rammed-earth construction can be difficult, and it often adds to the expense of building one of these homes. Turner and Karnaky ended up going with a trustworthy builder who was willing to learn the technique for their project. Securing building permits can also be tough if rammed-earth construction isn't common in your area.
"A lot of towns will just reject it out of hand," Turner said, "because it's new and weird."
Rammed-earth homes aren't just cost-effective to live in, they can be beautiful too. Homeowners like the layered look of the earth used to build their walls, and they'll sometimes add materials to the earth to affect the color. Many also like the way the thick walls make their homes quiet and peaceful.
Click ahead to see six "sand castles" you'd actually want to live in.