Magnolia Ave ADU: 26 Issues, Seismic & Accessibility

The project

A manufactured/prefab ADU project in California located in Seismic Design Category D. InspectMind reviewed the drawing set and identified critical deficiencies in seismic anchorage, fundamental accessibility violations, incorrect claims about HUD pre-emption of California codes, and extensive document coordination errors between floor plans, elevations, and site plans, issues that would have caused immediate permit rejection and potentially dangerous construction.

Project type

Manufactured home · California · SDC D

Codes referenced: 2022 CA Building Code · CBC 1604.4 · AISC 341 · CBC Chapter 11

Sample findings

1. Wood pad foundations in SDC D

   Critical

   Foundation uses wood pads on ground with 1/4" self-tapping screws. SDC D requires positive mechanical anchorage per CBC 1604.4 and AISC 341, structure could slide off foundation in earthquake.

2. Unstable three-point landing support

   Critical

   Free-standing landing supported by only three 4x4 posts with non-moment-resisting bases. A rectangular assembly on three points is geometrically unstable under lateral loads.

3. Location map and site plan show different properties

   Critical

   Location map shows one urban block location. Site plan shows property at a completely different location with different neighboring parcels, two entirely different geographical sites.

4. No accessible route to either entrance

   High

   Both entrances accessed via stairs only. CBC Section 1117A.3 requires ground-floor units to have accessible routes, steps are prohibited on accessible paths.

5. Incorrect HUD pre-emption claim

   High

   Notes claim "ALL MH PRE-EMPT CALIFORNIA REQUIREMENTS." HUD pre-empts unit construction only: site installation, fire protection, and accessibility still follow CBC per Section 420.1.

6. Sprinkler requirement contradiction

   High

   "ADU WILL NOT HAVE SPRINKLERS" contradicts CBC 903.2 and conflicts with scope noting "water tank for fire suppression system."

Issue categories

Structural & seismic

SDC D anchorage, unstable supports, missing member sizes

Accessibility

No accessible routes, 8" thresholds, stairs at all entries

Document coordination

Floor plan/elevation conflicts, location map errors, generic plans

Code compliance

HUD pre-emption errors, sprinkler contradictions, concrete strength

Value delivered

• 26 issues surfaced before permit submission
• Critical SDC D anchorage deficiency identified
• California accessibility violations flagged
• HUD vs CBC jurisdiction clarified