Alexander & Baldwin Inc. announced yesterday it will help homebuilder Gentry Cos. develop the initial 5,000-home phase of Gentry's long-planned Waiawa community.

A&B said it will invest about $50 million in the master-planned Central O'ahu project, and share the role of master developer with Gentry's Waiawa Development LLC.

The two Honolulu-based companies plan to develop some homes as well as sell 530 acres to other homebuilders for development.

The first homes are expected to be finished in 2009.

A&B said plans call for a variety of housing, including townhouses, duplexes, cluster homes and conventional single-family houses.

As part of obtaining county zoning approvals for the project's initial phase, 30 percent of homes must be sold to buyers earning 80 percent to 140 percent of O'ahu's median income, which last year was about $54,000 to $95,000 for a family of four.

A&B said the development plan calls for delivering more of the lower-priced homes up front, selling 600, or 60 percent, of the first 1,000 homes under the county affordable guidelines. Roughly translated today, affordable home prices would range from $250,000 to $390,000. Actual prices will vary depending on interest rates and median income at the time of sale.

The total Waiawa project, in the works since the mid-1980s on 3,700 acres of Kamehameha Schools land, is envisioned for 10,000 to 12,000 homes, two golf courses, parks, a commercial center, schools and other community facilities.

Buildout of the first phase, which primarily involves 5,000 homes, one golf course, parks and land given to the state for an elementary and middle school, is projected to take about 10 years.

Participation in the Waiawa project gives A&B its first large-scale residential project on O'ahu. The company currently is involved in developing residential real estate in Wailea, Maui, and in Kukui'ula on Kaua'i.

Gentry since 1968 has built about 15,000 homes and commercial projects mostly on O'ahu, including Waipio by Gentry and Ewa by Gentry.

Reach Andrew Gomes at agomes@honoluluadvertiser.com.