First Straw Bale ADU in San Diego

At Hubbell & Hubbell, we believe an ADU deserves the same level of architectural thought and care as a primary residence or commercial building. The homeowners envisioned an ADU that would expand their living space for family while generating income in the near term to help offset construction costs. Sustainability was equally important, but their budget made finding the right solution challenging. After months of exploring bids and prefabricated options, they found that most were either unaffordable or did not align with their environmental values.

The inspiration for straw bale construction came when one of the homeowners, a public media journalist, was editing a story about straw bale homes and wondered, “Why not look into that?” They ultimately chose Hubbell & Hubbell for the firm’s longstanding commitment to sustainable and innovative architecture.

Straw bale offered both environmental and aesthetic benefits. The homeowners wanted the material itself to become part of the architecture, so a portion of the straw bale wall was intentionally left visible as a sculptural detail. This little viewing window depicts the beauty and strength of the material used and grounds the owners in a sense of understanding all the resources involved.

Beyond its beauty, straw bale construction reduces the need for conventional materials such as drywall, wood, and paint. Plastered straw bale walls are airtight and have a high insulation rating (R-40 to R-50), which is more than three times greater than typical insulation (R-12 to R-15). These energy savings for space cooling and heating continue to accrue for the life span of the structure. When properly plastered and detailed, straw bale walls can also contribute to wildfire resilience—an increasingly important consideration throughout the West. This project was the first straw bale ADU permitted in the City of San Diego, continuing Hubbell & Hubbell’s decades-long leadership in advancing this innovative construction method.

Innovative materials can offer meaningful environmental and architectural benefits, but they require thoughtful planning and the right construction team. Homeowners considering straw bale should seek contractors with experience in the method—or a genuine willingness to learn. For these homeowners, finding the right fit took time, but that patience ultimately helped bring their vision to life.

We hope this ADU demonstrates the beauty and potential of sustainable, innovative construction and inspires others to consider alternatives to conventional building methods. As wildfire risk continues to shape communities throughout the West, materials and construction techniques that promote both environmental responsibility and resilience can play an important role in creating more sustainable, resilient neighborhoods.