ADU VALUATION GUIDE

Accessory Dwelling Unit Appraisal Guide

An accessory dwelling unit can add flexibility, income potential or family utility, but market contribution depends on legal status, design, privacy, access, quality and local demand.

Updated August 17, 2026. General appraisal information only; not legal, tax, lending, engineering or accounting advice.

Describe the space accurately

Document entrance, kitchen, bath, sleeping area, living area, utility separation, parking and connection to the main dwelling. Labels such as in-law suite do not replace physical facts.

Clarify whether the space is above grade, below grade, detached or inside an accessory building because reporting and comparison differ.

Research legal and permitted use

Zoning, permits, certificates and occupancy limits can affect use and marketability. Provide available approvals and identify later alterations.

The appraiser is not the code authority but must consider reasonably available information about permissible use and disclose uncertainty.

Separate ADU utility from finished space

A complete private unit may compete differently from a recreation room, guest suite or finished basement. The market may value flexibility without treating it as a legal second unit.

Analyze access, ceiling height, light, egress and whether the arrangement compromises the primary home.

Use comparable and income evidence carefully

Similar sales may be scarce, requiring broader searches, qualitative analysis and income context. Rent does not automatically convert to value.

Owner-occupants and investors may react differently, and restrictions may limit rental use. Contract leases should be compared with market evidence.

Identify assignment-specific rules

Lending, estate, divorce, tax and private-sale work can require different users, dates and reporting. A lender may have eligibility rules beyond value.

Raise the ADU before inspection so the appraiser can confirm scope, documents and data needs.

Planning checklist

  • Describe entrance, kitchen and bath
  • Identify above- or below-grade location
  • Provide zoning and permits
  • Clarify occupancy status
  • Document utility separation
  • Provide leases
  • Identify parking
  • Explain septic capacity information
  • Allow expanded comparable search
  • State intended use
Need an independent residential appraisal?

Send the address, intended use, effective date and unusual property features so the assignment can be reviewed before scheduling.

Request an Appraisal

Frequently asked questions

Does a second kitchen create an ADU?

Not by itself. Layout, facilities, access, use and legal considerations all matter.

Will construction cost equal value?

Not necessarily. Market contribution depends on utility and demand.

Can rent be capitalized?

Income may inform analysis when market participants rely on it, but method and weight are property-specific.

Is a basement apartment gross living area?

Below-grade space is generally reported separately under common residential appraisal conventions.