OnePhase Inc

OnePhase Inc. is a San Diego-based construction development and design company providing integrated services for residential homes, accessory dwelling units (ADUs), commercial projects, and renovations. The company takes a coordinated approach to development, combining architecture and design, zoning compliance, permitting, pre-construction planning, project management, and construction delivery under a streamlined workflow.

An accessory dwelling unit (ADU) — also known as a granny flat, in-law suite, backyard cottage, casita, or secondary dwelling unit — is an independent residential unit located on the same property as a primary residence. OnePhase supports ADU projects from early feasibility and planning through permitting and construction execution.

ADU Services

1. ADU Feasibility & Site Evaluation: OnePhase evaluates zoning and code constraints, site conditions, utilities, and project scope to determine a practical development strategy before construction begins.
2. ADU Design & Architecture: The company provides concept-to-permit plans, code-aware design, zoning compliance, and construction documentation for residential and ADU projects.
3. Entitlements & Permitting: OnePhase assists with entitlement strategy, permit coordination, and approval processes, helping align project documentation with applicable zoning and building requirements.
4. Pre-Construction Planning: Its pre-construction process includes scope development, budgeting, scheduling, trade coordination, procurement planning, and construction sequencing.
5. Construction Development: OnePhase coordinates the development process from feasibility through build-ready execution, connecting planning, consultant coordination, documentation, and construction phases.

What OnePhase Offers Beyond Construction

OnePhase operates with an integrated development and project management model. Rather than focusing solely on physical construction, the company coordinates critical stages of a project, including design, planning, permitting, budgeting, scheduling, and construction management.

Its broader services include:

• Architecture and design
• Residential construction
• ADU development
• Commercial construction
• Corporate projects
• Home renovations
• Project management
• Pre-construction planning
• Zoning compliance
• Entitlements and permitting
• Construction development

The company emphasizes early project planning to help establish realistic budgets, schedules, construction sequencing, and procurement requirements before work begins. Its project-management process also covers coordination among consultants, vendors, subcontractors, and other stakeholders.