Key Points

  1. Real estate agent Shalini Karnani Bonjour built a 1,100-square-foot ADU in California to house her mother, but the project took months longer and cost thousands more than planned.
  2. Bonjour cited difficulties in managing contractors, keeping the project affordable, and maintaining neighbor relations as key challenges.
  3. Her experience highlights the financial and logistical risks of ADU construction, even for those with real estate expertise.

A Personal Account of ADU Construction Challenges

After her father's death in 2024, real estate agent Shalini Karnani Bonjour moved her mother from Michigan to California to be closer to family. To accommodate her mother, Bonjour and her husband purchased a home with a backyard large enough for an accessory dwelling unit (ADU). In 2025, they began construction on a 1,100-square-foot ADU, expecting it to take six weeks. Instead, the project stretched over several months and exceeded their budget by thousands of dollars.

Bonjour, who has professional experience in real estate, described the process as overwhelming due to the many moving parts: managing contractors, controlling costs, and keeping neighbors satisfied. She noted that for someone without industry knowledge, the challenges would be even more daunting.

Her story illustrates that even those with real estate backgrounds can encounter significant obstacles when building an ADU, from unexpected expenses to timeline overruns.

Why ADU Projects Often Go Over Budget and Schedule

The Gap Between Expectations and Reality in ADU Construction

Bonjour's experience is not unique. ADU projects often face delays and cost overruns due to factors like permitting, contractor availability, and supply chain issues. For context, California has been actively encouraging ADU development to address housing shortages, but homeowners frequently underestimate the complexity. Even with real estate expertise, Bonjour struggled with the same pitfalls that catch many off guard.

Why Even Experts Can Misjudge ADU Projects

Real estate agents understand property markets, but construction management is a different skill set. Bonjour's mistakes—likely around budgeting, contractor selection, and timeline planning—stem from the inherent unpredictability of construction. Her advice to budget extra and vet contractors carefully underscores the need for thorough preparation.

Implications for the Growing ADU Market

As more homeowners consider ADUs for aging parents or rental income, stories like this serve as cautionary tales. They highlight the importance of realistic planning and the potential for financial strain. While ADUs can add value and housing supply, the process is fraught with risks that require careful navigation.

Practical Lessons for Homeowners Considering an ADU

If you're considering an ADU, learn from Bonjour's experience: budget generously and expect delays.

  • Budget an extra 20-30% beyond initial estimates to cover unexpected costs, as Bonjour's project went thousands over.
  • Vet contractors thoroughly—check references, licenses, and past ADU projects to avoid costly mistakes.
  • Communicate with neighbors early to address concerns and avoid disputes that can stall construction.
  • Plan for a longer timeline—even a six-week estimate can stretch to months due to permitting and weather.
  • Consider hiring a project manager if you lack construction experience, as managing multiple aspects is overwhelming.