Structural Plans And Calculations For ADU Above Existing Home
Adding a new ADU above an existing house requires careful structural review because the existing building must safely support the new floor, roof, wall, seismic, wind, and live loads. The design must confirm that the new 1,200 SF upper-level addition can transfer loads properly through the existing structure and down to the foundation.
Existing Building Review
The first step is reviewing the existing structural plans, framing layout, foundation system, wall locations, beams, posts, roof structure, and any previous calculations. This helps determine whether the existing house can support the proposed ADU or whether strengthening is required.
Structural Design Scope
The structural package may include new floor framing, roof framing, shear wall coordination, beam and header sizing, post and column checks, foundation load review, connection details, and load path verification. For projects in California, seismic and lateral load resistance are especially important.
Permit Review Comments
If the city or county issues plan review comments, the structural drawings and calculations may need to be revised to address reviewer questions. This can include clarifying load paths, updating details, adding calculations, revising framing plans, or providing additional notes for permit approval.
What We Can Provide
- Structural plans for ADU additions
- Structural calculations
- Existing building load review
- Floor and roof framing design
- Beam, post, and header sizing
- Shear wall and lateral design coordination
- Foundation capacity review
- Connection and anchorage details
- Response to permit review comments
- Permit-ready structural drawing package
Need ADU Structural Plans?
Send the architectural plans, existing structural drawings if available, project address, review comments, photos, and any previous calculations. We can prepare structural plans and calculations for ADUs above existing homes and help address permit review comments.