PALO ALTO, Calif. — Houzz, an online platform for home remodeling and design, has doubled the number of professional categories represented on the site at www.houzz.com.

The number of subscribers to the Houzz Pro+ program has grown rapidly this year, and company officials said the additions will offer visitors to the site information on service providers and vendors in categories including decks and patios, kitchen remodelers, home builders and home media.

Houzz officials say that more than 14 million people are using the site, up from four million a year ago. Ninety percent are homeowners who use the site to research and hire professionals, source products and find inspiration for projects, according to the company. A survey of 200,000 professionals on Houzz showed an increased demand for professional services in 2013, corresponding with reports of a recovery in the housing and renovation markets.

"Homeowners and professionals alike are telling us that they are moving forward with more building, renovation and design projects this year," said Liza Hausman, vice president of community. "Houzz provides homeowners with the absolute best resource to find the right professional for their project."