A North-Carolina-based company called Topsider Homes finds octagons the ideal shape for a house. Why? For one, "the shape encloses space more efficiently than its counterpart, the square," the company writes.
"An octagon has approximately 20 percent more space than a square with the same perimeter. Because this minimizes the external wall surface area, it decreases heat loss and gain. Additionally, an octagonal structure permits more natural light, aiding in the reduction of electric bills for illumination and heating in the winter and from a livability standpoint, octagonal designs allow for panoramic views and easier orientation on the building site."
"Topsider's unique octagonal homes permit 360 degree views making them very popular in vacation and scenic destinations, such as on the beach or the side of a mountain. They adapt to the terrain and climate of almost any building site and can be built on a wide range of foundation types, including pedestals, pilings, basements, slab and crawl-spaces."
The company, which has been in business since the 1960s, writes that they have "created a new genre of building designs by marrying their unique pedestal foundation to an octagonal structure using a post and beam building system." They not only sell plans for octagonal houses that utilize this system, but they also prefabricate the structural components, shipping them out as kits.
Where this has an interesting application is in the area of home additions, which the company also specializes in. "Because many home additions must be added onto sloping terrain on the side or back of the existing structure," they write, "our unique ability to design for any type of foundation can make a big difference. We can build room additions on pilings, pedestals, slabs, crawl-spaces and even basements."