1400 Montefino

An empty office building becomes 49 condos

A vacant office building on Montefino Avenue in Diamond Bar would be torn down and replaced with 49 for-sale condominiums. The developer, Intracorp, filed the project in 2025, and the city circulated its environmental review in the spring of 2026. No public hearing has been scheduled yet.

What's proposed

Forty-nine three-story condominiums on about 3.9 acres — seven detached homes and 42 attached, spread across 28 buildings. The floor plans run roughly 1,940 to 1,988 square feet across three designs, all for sale rather than rental. Parking totals 120 spaces: 98 in private two-car garages, plus 22 uncovered guest spaces. At 49 units on 3.9 acres the project works out to about 12.5 homes an acre — a low-rise, garage-first product closer to townhomes than to the apartment density the same acreage could carry. The site is the former Liferay US headquarters, a two-story office building of about 55,221 square feet that would be demolished.

The site and the corridor

The parcel sits off Montefino Avenue near the SR-60 freeway, on land currently zoned for commercial office use. Diamond Bar has been converting underused office and commercial land to housing to meet its state-assigned housing targets, and this is a clear example: an office building that lost its anchor tenant, on a site large enough to carry a small for-sale community. Because it is a market-rate for-sale project, the units would be sold individually rather than leased — which is why the entitlement package includes a tentative tract map to create the airspace parcels.

The design

SDK Design Group designed the project. Renderings described in Urbanize LA's coverage show a Spanish-style scheme with white stucco walls and tile roofs. No agency-hosted plan set image with clear provenance has surfaced for use here.

Timeline

• July 2025 — The city solicits CEQA consulting services for a 49-unit condominium project at 1400 Montefino Avenue
• 2026-03-10 — Diamond Bar files a Notice of Intent to adopt a Mitigated Negative Declaration (SCH 2026030434) for Planning Case PL2025-29; public review runs March 11 to April 10
• 2026-04-30 — Intracorp holds a community meeting at the Diamond Bar Center to present conceptual plans
• May 2026 — The Final Initial Study / Mitigated Negative Declaration is issued, incorporating responses from Caltrans, the county sanitation districts, and Southern California Edison

How it got here

The project needs an unusually full set of approvals because it changes what the land is allowed to hold. A General Plan amendment would redesignate the site from commercial to residential. A zone change would move it from Commercial Office (CO) to a residential planned-development district (RMH-PD). A tentative tract map subdivides the site so the 49 units can be sold as condominiums. A conditional use permit and development review cover the planned-development modifications, and a development agreement would lock in terms between the developer and the city. For environmental review, the city prepared a Mitigated Negative Declaration — a finding that the project's impacts can be reduced to less-than-significant levels with conditions, rather than a full environmental impact report. The Final IS/MND, prepared by De Novo Planning Group, identified no significant impacts after mitigation.

What still has to happen

The project is under environmental review and has not been heard. It still needs Planning Commission review and City Council action on the General Plan amendment, zone change, map, and development agreement before it could move toward permits. No hearing date had been published as of August 2026. Secondary coverage estimates a construction start in late 2026 and roughly a 30-month build if it is approved on schedule, but that is an estimate, not a permit.

Why this one matters

This is an office-to-residential conversion on a freeway-adjacent commercial parcel — the kind of adaptive reuse cities across the valley are leaning on as office demand softens. It is also a for-sale product rather than apartments, which is less common on this board, where most new housing is rental. Whether Diamond Bar's council is willing to rezone commercial office land for detached-and-attached condos is the question this project tests.

What this means if you live nearby

A long-empty office building on Montefino would come down and be replaced by 49 for-sale homes with two-car garages. Nothing is approved yet — the project is still in environmental review, with hearings to come. If you own or watch commercial-office land near the SR-60 in Diamond Bar, this is an early read on what the city will entertain rezoning it for.