Service

Accessory
Dwelling
Units

Detached ADU, garage conversion, or junior ADU. We provide the structural plans your contractor needs to build and your building department needs to issue a permit. Designed for California seismic compliance from the start.

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Why it matters

ADUs need structural engineering from the ground up.

A detached ADU behaves like a small standalone home. It needs to safely resist gravity, wind, and seismic forces, the same demands placed on your primary residence. Foundations, framing, and lateral systems all have to work together to carry loads from the roof and walls into the ground.

Attached ADUs, garage conversions, and junior ADUs add another layer of complexity: new loads have to integrate with an existing structure that wasn't designed with the addition in mind. Getting that right requires looking at both the new and existing structure together, not just the new portion.

What we address

Common structural considerations for ADUs.

Every ADU project has unique demands depending on the type, site conditions, and local requirements. These are the structural areas we address on most projects.

01

Foundations & Slabs

Detached ADUs typically require a new reinforced concrete slab or raised foundation. We size the foundation for soil conditions, specify anchor bolts and holdowns to secure the framing, and coordinate with the geotechnical requirements of your site.

02

Framing & Engineered Beams

Floor and roof framing members are sized to support gravity loads while limiting deflection. Engineered wood or steel beams allow for open layouts, large windows, and flexible interior spaces without sacrificing structural performance.

03

Lateral & Seismic Systems

Shear walls, collectors, and metal connectors resist wind and earthquake forces and carry them through a continuous load path from roof to foundation. California’s seismic zone demands careful detailing at every connection. We design each element to work as part of the whole system.

04

Integration with Existing Structures

Garage conversions and attached ADUs rely on framing that was not originally designed for residential occupancy. Structural upgrades often include slab reinforcement, new beams, added bracing, and improved connections. We assess the existing conditions and design only what is needed.

ADU wood framing with plywood shear wall panels installed
ADU framing with plywood shear wall panels installed.
ADU structural plans are prepared in accordance with the California Building Code and applicable local amendments. Our drawings are organized and detailed to minimize plan check comments and keep your project on schedule.

Planning an ADU project?

Share your project details and we’ll follow up within 1–2 business days to discuss scope and next steps.

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