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Guide

Unpermitted Work: Red Flags Before You Buy

By Karla I. Vasquez, REALTOR® · Keller Williams Realty Danville · Reviewed October 2026

Quick answer

Unpermitted work is any construction done without the required building permits, like a garage turned into a bedroom, an added bathroom, or a backyard unit. It's common in the Bay Area, and it isn't always a deal-breaker, but it can affect safety, insurance, financing, future permits and resale. Before you buy, compare what you see with the permit history, read the seller's disclosures closely, and have a qualified inspector look at anything that doesn't add up.

Why unpermitted work matters

Permits exist so a building official can check structure, electrical, plumbing, fire safety and energy rules. When that review is skipped, nobody independent has confirmed the work is safe. For a buyer, that can mean:

  • Safety unknowns hidden behind finished walls.
  • Future costs if the city or County later requires the work to be permitted, opened up for inspection, corrected or removed.
  • Complications when you apply for your own remodel or ADU permits.
  • Questions from appraisers, lenders or insurers about rooms or square footage that don't match records.

What are the red flags of unpermitted work?

From my construction background, these are the things that make me ask more questions:

  • Square footage or bedroom count doesn't match County records or the listing.
  • Garage converted to living space, especially with no garage door and a new wall.
  • A bathroom or kitchen in a basement, attic, garage or backyard structure.
  • Mixed materials or rooflines where an addition meets the original house.
  • Electrical clues: extension cords as permanent wiring, a cluttered or crowded panel, ungrounded outlets in new rooms.
  • Plumbing clues: low water pressure in new bathrooms, odd drain lines, a water heater squeezed into a closet.
  • Low ceilings, small windows or one exit in a "bedroom."
  • Fresh drywall or paint in one area only, which can hide recent changes.

How do I check permit history on a home?

Start with the office that has jurisdiction:

  • Unincorporated Contra Costa (like Alamo): The County's ePermits Center shows building permit and planning application history from 1980 forward. Plans themselves aren't online; you can request records through the County's Records Research division. Code Enforcement can tell you about violation history.
  • Cities like Danville, Concord or Walnut Creek: Contact that city's permit center or building department.

Then compare the history with the home in front of you and with the seller's disclosures.

What the seller has to disclose

California's Transfer Disclosure Statement asks sellers directly whether they know of room additions, structural modifications, or other alterations or repairs made without necessary permits, and whether any are not in compliance with building codes. Read those answers carefully, along with the inspection reports in the disclosure package. If something is checked "yes," or if what you see doesn't match the answer, ask questions in writing during your contingency period.

Options if you find unpermitted work

Every situation is different, but buyers often:

  • Get a specialist opinion from a licensed contractor, engineer, electrician or plumber.
  • Ask the permit office what it would take to legalize the work, before you remove contingencies.
  • Negotiate price or credits, or ask the seller to address it.
  • Walk away if the risk or cost doesn't make sense.

A reminder: completed new construction can also be reassessed for property taxes, so legalizing a large addition may affect your tax bill.

Karla's tips

  • Bring a builder's eye to showings. As Owner & Principal of KCK Construction & Remodeling, I look at framing, rooflines, panels and plumbing as part of how I guide my buyers.
  • Pull permits before you write the offer when a home has obvious additions. It's easier to plan than to scramble.
  • Get written estimates, not guesses. Real numbers help you negotiate and decide.
  • Don't count rooms you can't legally use. Value the home based on what's permitted, and treat the rest as a bonus with a cost.
  • ¿Prefiere español? I walk buyers through inspections and disclosures in Spanish. (510) 677-8695.

En español: lo básico

El trabajo sin permiso es cualquier construcción hecha sin los permisos requeridos, como un garaje convertido en cuarto o un baño agregado. No siempre impide la compra, pero puede afectar la seguridad, el seguro, el financiamiento y futuros permisos. Antes de comprar, compare la casa con el historial de permisos del Condado o la ciudad y lea con cuidado la declaración del vendedor, que pregunta sobre ampliaciones o reparaciones sin permiso. Si encuentra algo, pida la opinión de un contratista con licencia y consulte la oficina de permisos antes de quitar sus contingencias.

Sources

General information only, not legal, tax or financial advice. Rules and fees change; confirm with the County, the Board of Equalization, your tax professional or an attorney. Karla I. Vasquez is a REALTOR® and Registered LDA, not an attorney.