At BZ Build Co. we believe in building more than just structures—we build trust, resilience, and a sense of home.

Our Story

John Brennan, a seasoned contractor with a portfolio of over 250 custom-built homes in the Los Angeles area, has always been committed to quality. No cookie-cutter developments, no mass-produced track houses. Every home is uniquely designed and built with care. Over the years, John has led the construction of nearly 100 homes annually, alongside large-scale industrial remodels, all while prioritizing craftsmanship, efficiency, and integrity.

On Wednesday January 7th, 2025, the world changed when Ashlyn Mangandi lost her home to the Eaton Fire. A force of nature in both work and life, Ashlyn has been the glue in our projects, elevating everything she touches with her dedication to hospitality and excellence. That day wasn’t just a personal loss—it became a call to action, and BZ Build Co. answered.  

Why We Exist

The heart of BZ Build Co. is trust. When you build with us, you’re not just building a house —you’re building a relationship with a partner who values transparency and reliability. We understand that not every project runs perfectly, but trust is at the core of everything we do.

John Brennan founded Brennan Construction over 15 years ago, growing it into the leading general contracting firm in Burbank for the past four years. His partnership with Ashlyn began after successfully developing multiple residential and commercial properties together. The success they achieved on past projects inspired the idea of scaling their business together, ultimately leading to the creation of BZ Build Co. This collaboration naturally extends to the rebuilding of Altadena, Ashlyn’s hometown, with the same dedication and vision that has defined their work.

Rebuilding Altadena is more than just construction—it’s about restoring a community with the care, efficiency, and dedication it deserves.

Our Promise

✔ We always do the right thing. Period.

✔ We bring trust and integrity to every project.

✔ We are committed to rebuilding Altadena, one home at a time.

Ashlyn Mangandi and John Brennan have worked side by side on countless projects—from full home builds to industrial remodels, and everything in between. With Brennan’s expertise and BZ Build Co.’s unwavering dedication, we are here to bring that trust, quality, and commitment to Altadena’s rebuilding efforts.

Together, we’re not just building homes—we’re rebuilding Beautiful Altadena.