Wealthy Americans increasingly look underground for home expansions

Trend has spread to the Hamptons and to townhouses in the city
March 19, 2012 09:30AM

In an effort to mitigate the ostentatiousness of oversized mansions and to comply with restrictions on single-family home sizes, super-rich Americans are increasingly adding square-footage where it can’t be seen — underground.

For example, presidential candidate Mitt Romney, who has already caught some heat for his displays of wealth, filed an application to replace a single-story 3,000-square-foot home in La Jolla, Calif., with a 7,400-square-foot home with an additional 3,600 square feet of underground space.

While the trend is most evident in Beverly Hills and the United Kingdom, it has begun to reach the Hamptons, too. Famed builder Joe Farrell said he’s noticed increased demand for so-called trophy basements. His “Sandcastle” home, which is on the market for $43.5 million and has been rented for as much as $550,000 for a two-week stay, has a 10,000-square-foot basement with a skateboard half-pipe, a spa, a squash court and a disco.

In New York City, townhouse owners are also looking to expand underground to add amenities like basketball courts, gyms and swimming pools to their classic city home, the Journal said. But the additions can be expensive. Engineering challenges can push the cost of gut renovating a basement to 50 percent to 100 percent more than $800 to $1,000 cost per foot of a high-end above-grade townhouse, according to a Manhattan-based engineer. [WSJ]