Building an ADU in San Gabriel

It can refuse a non-compliant design, but state law has substantially narrowed the grounds. California ADU statute requires cities to permit units meeting objective standards and prevents them from applying discretionary design review to deny a conforming application, and it overrides several local rules that used to block these projects, including many owner-occupancy requirements and most added parking demands near transit. What the city can still enforce are objective standards: height limits, setbacks, lot coverage, fire access and building code. The practical consequence is that a refusal is usually a fixable plan problem rather than a verdict on the project. If you are told your lot simply cannot have an ADU, it is worth getting a second opinion from a designer who works under the current statute.

An ADU generally gets its own address for mail and emergency response, which the city assigns during the permit process. Utility metering is the more nuanced question. A separate electric meter lets you bill a tenant directly and keeps your own usage clean, but it costs more up front and requires coordination with the utility on lead times that can be long. Sharing the main house meter is cheaper and faster but means you are absorbing the tenant's usage or agreeing some private split, which is a frequent source of friction. Water and sewer are often shared. Decide this early, because it affects the panel, the trenching and the plan set, and changing your mind after plan check is expensive.

Ask how many ADUs they have completed in the San Gabriel Valley specifically, and ask to speak to owners of two of them, ideally one that went smoothly and one that did not. Ask who draws the plans and who carries responsibility if plan check rejects them. Ask for the payment schedule in writing and make sure it tracks completed work rather than front-loading the deposit. Ask what their change order process is and what markup applies. Verify the licence status and any bonding directly with the California State License Board rather than taking a number on a business card at face value, and confirm insurance by asking for a certificate sent to you by the insurer, not a photocopy. Tegula Stone connects homeowners with independent specialists and does not perform the work or vouch for any contractor, so these checks remain yours to make.

That depends on inputs only you have, and anyone who answers confidently without them is guessing. The honest framework is to compare total delivered cost, including design, fees, utilities and a contingency of at least ten to fifteen percent, against realistic local rent for a unit of that size, minus vacancy, maintenance and any additional property tax assessed on the new construction. In much of the San Gabriel Valley the rental math is reasonable, but it is a long payback rather than a quick return, and it is sensitive to how much the site work costs. Many owners build for a family reason instead, housing a parent or an adult child, and treat the return as secondary. Be clear with yourself about which of those you are doing, because it should change how much you spend on finishes.

Four things, in roughly this order of frequency. First, site conditions discovered after demolition: an undersized sewer lateral, a slab that cannot be built on, or soil that requires a deeper foundation. Second, an underspecified contract, where allowances are set low and the real cost of finishes lands as change orders. Third, owner-driven changes after permit, which trigger revisions and restart parts of the review. Fourth, cash flow, where a payment schedule weighted toward the start leaves too little leverage at the end and the last ten percent of the work drags for months. You can defend against all four by paying for a thorough site investigation before design is finalised, insisting on a line-item contract, freezing the design at submission, and keeping a meaningful final payment tied to the certificate of occupancy.