Kamehameha Schools has received an extra 10 years to finish redeveloping 29 acres in Kakaako under a master plan amended by a state board Wednesday.

The trust also received assurance that it can use a state affordable-housing law to produce homes at lower sale or rental prices in more dense towers without affecting a maximum master-plan density limit.

Board members of the Hawaii Community Development Authority, a state agency regulating development in Kakaako, voted unanimously to approve the changes following an April public hearing on the request that Kamehameha Schools made in February.

“We’re very grateful for (board) members’ time and attention and support of the continuation of this master plan for Kakaako,” Calvert Chipchase, an attorney representing the trust, said at Wednesday’s HCDA meeting.

Kamehameha Schools had requested at least five additional years to complete its master plan covering nine contiguous blocks mauka of Ala Moana Boulevard between South Street and Ward Avenue.

The master plan approved in 2009 was set to expire in 2024, and the trust advised HCDA that it could’t reasonably finish by the deadline.

Kamehameha Schools is about half done with development under the plan, which now envisions producing more than 2,750 homes and over 500,000 square feet of commercial space.

To date, the trust with partners has produced the retail complex Salt along with 1,336 homes at high-rise and midrise projects that include The Collection, Keauhou Place, Keauhou Lane, Flats at Puu­nui, 400 Keawe and 680 Ala Moana.

Under HCDA rules, the agency’s board may permit up to a 15-year extension from when an extension is sought, which in the Kamehameha Schools case could have been to 2036. HCDA staff recommended an extension to 2034, which the board approved.

Kamehameha Schools said the additional time will allow it to pursue delivery of more affordable housing than HCDA rules require.

The agency requires that 20% of new homes in high- density projects be priced for moderate-income households. Kamehameha Schools has exceeded this for what it has produced so far, with 34% of homes meeting HCDA affordable-housing guidelines.

Under the trust’s amended vision for five blocks not yet redeveloped, market-rate housing towers would rise on three blocks fronting Ala Moana while two blocks immediately mauka are envisioned for two towers where at least 50% of homes would be reserved for households with low to moderate incomes.

The two predominantly affordable-housing towers would take advantage of incentives offered under a state program that can permit zoning rule exemptions and tax breaks.

The program, sometimes referred to as 201-H after the statute chapter governing it, will allow Kamehameha Schools to make the two towers more dense without counting toward a maximum density calculation for its master-plan area.

Construction labor organizations submitted testimony supporting the trust’s request. The Ala Moana -Kakaako Neighborhood Board endorsed the deadline extension but did not comment on the trade-off regarding higher density in return for more affordable housing in a resolution submitted to HCDA.

The trust projects that its next tower could start construction as soon as late 2023.

Kamehameha Schools is one of two large landowners in Kakaako with master redevelopment plans approved by HCDA about a decade ago.

Texas-based Howard Hughes Corp. is the other, and has so far largely produced luxury towers with average unit prices at or above $1 million while also meeting HCDA’s 20% moderate-priced housing requirement.

The Hughes Corp. plan covers 60 acres envisioned for more than 4,500 homes in 16 towers, along with public parks and 1 million square feet of retail space Diamond Head of the Kamehameha Schools lands.

Hughes Corp. has finished four towers and has three under construction with a total of 3,046 homes. The company earlier this year also received HCDA approval to move ahead with two more towers with 1,243 units.