Civic Infill Works Northern Colorado

News / Due diligence / Buyers and realtors

Due diligence

Buying a house with ADU potential? Do this before you make an offer

A property described as “could add an ADU” is a property whose value depends on a project that has not been built and rules that have not been verified. The work of due diligence is to test that assumption before the offer is written, not after.

By Shelby King, Civic Infill Works. Published May 26, 2026.

Buyers ask one of two questions about ADU potential. Can this property support an ADU at all? And if it can, what will it actually cost in time, money, and operating risk? A listing description does not answer either. A real-estate agent can flag the question, but cannot underwrite it. Civic Infill Works produces written due-diligence memos on a transaction timeline for precisely this situation.

Questions to verify before the offer

  1. Jurisdiction. Is the parcel inside city limits, inside a Growth Management Area, or unincorporated? The rulebook follows from this answer.
  2. Zoning permission. Does the current zone allow an ADU as of right, with administrative review, or only with a discretionary approval? “Could” and “is allowed” are not the same.
  3. Primary dwelling status. Many ADU pathways require a single-unit detached primary dwelling. A duplex, attached, or non-residential primary structure can change the path.
  4. Floodplain, easements, and plat restrictions. A parcel can be allowed under zoning and still constrained by floodplain rules, recorded easements, covenants, or plat restrictions.
  5. Utilities. Water tap availability, sewer capacity, electric panel and service size, gas service, and (in unincorporated areas) well and septic capacity can each disqualify an otherwise allowed project.
  6. Access. Alley, driveway, fire, and parking access shape what configurations are possible, and sometimes what configurations are possible at all.
  7. Financing. The lender’s view of ADU value, appraisal approach, and rental-income underwriting affects what the buyer can carry. The bank does not underwrite the dream; it underwrites the project as proposed.

What a buyer due-diligence memo includes

  • Jurisdiction confirmation and citation to the controlling rules.
  • Zone-level ADU permission summary and any administrative-review notes.
  • Site-level review for floodplain, easements, and likely setback constraints.
  • Utility first-look using publicly available information and a list of utility questions the buyer should ask before closing.
  • Likely configurations (detached, attached, garage or basement conversion) and the tradeoffs of each.
  • Identified risks the buyer should price into the offer or condition the offer on.

Civic Infill Works does not represent buyers or sellers in real estate transactions

The firm is fee-only and independent. It does not earn referral fees from agents, inspectors, lenders, or builders. It produces a written first read so a buyer’s decision is grounded in evidence, not optimism.

For realtors and brokerages

If your client is asking ADU questions, the safest script is short: “The property could support an ADU only after a parcel-level review — I can connect you with an independent advisor who produces a written due-diligence memo on a transaction timeline.” Civic Infill Works does not pay or accept referral fees and discloses any prior engagement with a party in writing.

How to start

Send the parcel address (and listing link, if available) along with the transaction timeline to hello@civicinfillworks.com. The standard memo turnaround is set against the inspection or due-diligence window in the contract.

Request a buyer due-diligence memo Start the Diagnostic