How Appraisers Actually Value a Sacramento-Region ADU in 2026

Quick Answer

An appraiser doesn't apply a percentage bump for an ADU. They look for a comparable sale, an actual house with an actual ADU that actually sold, and describe your unit's effect on value and marketability against that comp. In a region where most permitted ADUs are only a few years old, that comp pool is thin almost everywhere, Sacramento included. The appraisal report itself is generally the standard one-unit form, not a small-income-property form, with the ADU broken out on its own line and a separate rental schedule attached where relevant. Fannie Mae changed a real rule in 2026: a portion of an ADU's projected rent can now count toward mortgage qualification, capped and documented in specific ways. None of that changes what happens at resale, where the sales comparison approach still runs the show. This guide walks through the mechanics, cites the actual sources, and tells you plainly where a real number exists and where it doesn't yet. Run the ADU cost calculator for a construction range, or call (530) 204-8294 to talk through your specific property.

The Question We Get Asked Wrong

Almost every homeowner who calls us about an ADU eventually asks some version of the same question: how much value does this add? It's a fair question. It's also the wrong shape for how an appraisal actually works.

A percentage answer implies a formula, ADU square footage times some multiplier, applied uniformly to every house. That's not how a residential appraiser is trained to work, and it's not how Fannie Mae or Freddie Mac's own guidelines describe the process. An appraisal for a one-unit property is built on the sales comparison approach: find recently sold, similar properties, adjust for differences, land on a supported number. When the subject property has an ADU, the appraiser's job is to find comparable sales that also have an ADU, or to explain clearly why they couldn't and what they did instead.

That distinction matters more here than in a market where ADUs have been common for decades. This region's ADU activity is recent. California's statewide ADU reforms started phasing in around 2017 and expanded substantially with a second wave of legislation in 2020, and most of the actual building in Sacramento, Davis, Elk Grove, Folsom, Roseville, Woodland, West Sacramento, and Dixon has happened since then. That leaves a genuinely small pool of properties that both have a permitted ADU and have gone through a full closed sale, which is exactly what a clean appraisal comp requires.

We're not appraisers, and we won't pretend to be. We're a licensed general contractor that builds the units this whole conversation is about. What follows is the actual framework appraisers and lenders use, pulled from Fannie Mae and Freddie Mac's own published guidance, laid out plainly so you know what to expect before you talk to a lender or list your house.

The Comp Problem, Stated Plainly

Fannie Mae's Selling Guide, section B4-1.3-05, addresses ADUs directly in the improvements section of the appraisal report. Two requirements stand out.

First, an ADU's living area gets reported on its own line in the appraisal grid, separate from the primary dwelling's finished square footage, unless the ADU sits inside the main house with interior access and is above grade. That's a formatting rule, but it matters: your ADU isn't quietly folded into "the house." It's identified as its own feature with its own effect on value.

Second, and this is the part that actually determines your number: when there's an ADU, the appraisal report must include a description of the unit and an analysis of its effect on value and marketability. To support that analysis, the guide is specific about what counts. An aged settled sale, a comparable property with an ADU that has already closed, qualifies as a true comparable. An active listing or a sale currently under contract doesn't qualify as the comp itself; it can only serve as a supplemental exhibit showing marketability, meaning it shows buyer interest exists, not what the market actually paid.

Read that again in the context of a market this young. If Sacramento, Davis, or any of the smaller cities in this cluster doesn't yet have many aged settled sales of ADU-equipped homes, and in a lot of neighborhoods it genuinely doesn't, the appraiser is working with a shorter list of qualifying comps than they'd have in, say, Los Angeles, where ADU construction has a longer track record. That doesn't mean your ADU won't appraise well. It means the appraiser may need to reach further geographically or accept a slightly older comp to find one, and it means two appraisals on similar houses can land at different numbers depending on which comps each appraiser found.

Want a construction number to plan around while that appraisal question plays out? Run the ADU cost calculator or call (530) 204-8294, it takes about two minutes.

What Form Actually Gets Used

We hear a version of this misconception often: that adding an ADU turns your house into a "multi-unit property" for appraisal purposes, which would mean a different, more complex form. That's generally not correct as long as the property remains a legal single-family residence with an accessory unit.

The Small Residential Income Property Appraisal Report, Form 1025, is built for true 2-4 unit properties, duplexes, triplexes, fourplexes. An ADU doesn't turn your house into one of those. It's still a one-unit property, so the appraisal generally still runs on the standard Uniform Residential Appraisal Report, Fannie Mae Form 1004 or its Freddie Mac equivalent, Form 70.

What changes is the addendum work. A Single-Family Comparable Rent Schedule, Form 1007 on the Fannie Mae side or Form 1000 on the Freddie Mac side, gets attached specifically to document the ADU's market rent, drawing on comparable rentals rather than comparable sales. Fannie Mae's guidance notes that this form gets accepted with an explanation from the appraiser that the estimated market rent applies to the ADU specifically, not the whole property, since the form was originally built with a different use case in mind. It's a workaround applied carefully, not a purpose-built ADU form, which is a small but real sign of how new this whole framework still is.

Fannie Mae's 2026 Rule Change: ADU Income Toward Qualification

This is the part that's actually new, and it's worth getting exactly right rather than rounding it off.

Fannie Mae published Selling Guide Announcement SEL-2025-08 in October 2025, and the change took operational effect through Desktop Underwriter version 12.1 the weekend of March 21, 2026. For the first time, projected rental income from an ADU can be counted toward a borrower's qualifying income on a purchase or a limited cash-out refinance of a one-unit primary residence.

The rule comes with real limits, not a blank check:

• The 30% cap. ADU rental income counted toward qualification can't exceed 30% of the borrower's total qualifying income.
• The 75% haircut. Only 75% of the lesser of the appraiser's estimated market rent (via Form 1007) or a current signed lease counts. The full rent number never gets used.
• Purchase and limited cash-out refinance only. A standard cash-out refinance doesn't qualify under this specific provision.
• One-unit primary residence. Investment properties and second homes are outside this rule.
• One ADU counts, even if more than one exists on the property.
• Documentation is specific. A current signed lease, or Form 1007 (Fannie Mae) or the equivalent rent schedule on the Freddie Mac side, establishes the number.

Freddie Mac runs a parallel structure through its own guide: rental income from an ADU generally can't exceed 30% of the borrower's total monthly effective income, and where there's no prior rental history on the ADU, 75% of the lesser of the appraiser's fair market rent (via Form 1000) or a lease-stated rent can be considered.

The appraiser's own responsibility in all of this is worth noting, because it cuts against over-optimism: Fannie Mae's guidance specifically instructs appraisers to stay alert to the risk of double counting the ADU's value, once in the sales comparison analysis and again in the rental income analysis. The two numbers are supposed to describe different things, not stack on top of each other.

None of this is guaranteed to apply to your loan. Rules like this get refined, lenders implement them on their own timelines, and your specific scenario, credit profile, and loan type all matter. Confirm the current version with your lender before you build a budget around it. For the fuller financing picture, including HELOCs, construction-to-permanent loans, and what we deliberately didn't publish because we couldn't verify it, see our ADU financing guide.

The FHFA Data Point: What California's Own Numbers Actually Show

Most "ADUs add X% to home value" claims floating around the internet trace back to nothing, a marketing line repeated until it sounds like fact. There is one real, named, government-sourced dataset worth citing here, and it's worth being precise about what it does and doesn't say.

The Federal Housing Finance Agency publishes Uniform Appraisal Dataset Aggregate Statistics, built from purchase-loan appraisals submitted to Fannie Mae and Freddie Mac. Its analysis of California properties from 2013 to 2023 found that median appraised values for properties with an ADU rose from roughly $550,000 in 2013 to roughly $1,064,000 in 2023, an annualized growth rate of 9.34%. Properties without an ADU rose from roughly $405,000 to $715,000 over the same period, an annualized rate of 7.65%.

Two honest caveats belong right next to that number. First, it's a statewide figure, not a Sacramento-region breakout; FHFA's published analysis doesn't isolate this metro. Second, it's a correlation across a decade of a rising market, not proof that the ADU itself caused the extra 1.69 percentage points of annual growth every year on every property; homes with ADUs may differ from homes without one in other ways too, lot size, location, owner investment level, that also affect appreciation. What it does show, credibly, is that ADU-equipped properties in California have not been a value drag over the past decade, and the data leans meaningfully in the other direction.

That's a more honest answer than a flat percentage, and it's the only externally sourced figure in this guide we're comfortable standing behind.

Refinancing After You Build: Getting the Timing Right

If the plan is to build an ADU and then tap the added value through a cash-out refinance or HELOC, timing the appraisal correctly matters more than almost anything else in this process.

Finish the unit before the appraisal, not during. An appraiser working from plans and a contractor's progress estimate is valuing an unfinished asset. Most lenders discount that heavily, and some won't count it toward value at all until there's a certificate of occupancy. A construction loan or construction-to-permanent product is generally the right tool for financing the build itself; the cash-out refinance or HELOC against the finished value comes after the unit is done and signed off.

Get final permits closed out, not just issued. A permit that's open but not finaled is a red flag on an appraisal and can hold up a loan entirely. If your Sacramento city, Davis, Elk Grove, Folsom, Roseville, Woodland, West Sacramento, or Dixon permit has been sitting open for a while after construction wrapped, closing it out is worth doing before you talk to a lender, not after the appraiser shows up and flags it.

Line up a lease if you can, before the appraisal. A signed lease gives the appraiser and the underwriter a concrete number to work from, rather than relying entirely on Form 1007 or Form 1000's estimated market rent. It doesn't replace the appraiser's independent judgment, but it's real documentation that supports your case.

Expect the appraiser to explain their comp choices, and ask if they don't. Given how thin the aged-settled-sale pool still is in parts of this region, an appraiser may need to pull comps from a wider radius, use an older sale, or lean on active listings as supplemental marketability evidence rather than a hard comp. You're entitled to see the comps used. If something looks off, a reconsideration of value request through your lender is a normal, available step, not an unusual one.

For the property tax side of what happens after a build, which is a separate process from the appraisal but often gets confused with it, see our ADU property tax reassessment guide. Reassessment and appraisal are two different systems asking two different questions, and conflating them is a common, avoidable mistake.

What Actually Moves the Number

Setting aside the forms and the rules, a few practical factors show up again and again in how an ADU's value gets described in an appraisal.

Permitted status is not optional. An appraiser working from a lender-ordered report is describing a legally compliant structure. An unpermitted ADU, even a well-built one, typically gets excluded from the valuation entirely, described as a non-conforming improvement, or flagged as a lending risk. If yours was built without final sign-off, resolving that before a refinance or a listing is worth the time and cost.

Independence of the unit matters. A separate entrance, its own kitchen, its own bathroom, and independent utility metering where applicable all support the ADU being treated as a real, functioning accessory unit rather than a bonus room with a hot plate. That independence is part of what an appraiser is evaluating when they describe the unit's effect on marketability.

Construction method matters less than finish quality. A garage conversion and a ground-up detached build go through the same appraisal mechanics. The garage conversion typically costs less to build, $60,000-$140,000 in construction or $80,000-$160,000 all-in, against $175,000-$340,000 for a standard detached new-build, but a well-finished conversion with real independence isn't penalized on the appraisal for having started life as a two-car garage. What shows up in the description is the finished product, not the construction history.

Local rent comps drive the Form 1007/1000 number. In a UC Davis-adjacent market or a Sacramento neighborhood with strong rental demand, the market rent comparable to your ADU carries real weight. That's a separate question from the sales comparison approach, but it feeds into the rental income analysis if you're using the 2026 Fannie Mae qualification rule.

Cost Baseline for This Region

Whatever the appraised value ends up being, the construction number is where financing conversations actually start. Held consistent with our other cluster guides:

These are regional planning ranges, not a quote for your specific lot. Site conditions, utility distance, foundation type, and finish level all move the number in either direction. Run the ADU cost calculator for a range built around your property, about two minutes, no site visit required, or call (530) 204-8294 to talk it through with us directly.

What We Verified, and What We Didn't

Every appraisal and lending rule cited above was pulled from Fannie Mae's Selling Guide (section B4-1.3-05, current as of its 2025 update, and Selling Guide Announcement SEL-2025-08) and Freddie Mac's own published ADU guidance, not a mortgage blog summarizing them secondhand. The FHFA data point comes from the agency's own Uniform Appraisal Dataset Aggregate Statistics blog post, a primary government source.

What we deliberately did not publish: any Sacramento-region-specific appraised-value percentage, because no dataset we could verify breaks this metro out separately from the statewide FHFA figure. Any specific dollar comp, meaning an actual closed sale price of an ADU-equipped house in this region, because we're a contractor, not a licensed appraiser or real estate agent with MLS access, and printing an invented number would be worse than printing none. A precise count of how many ADU-equipped homes have resold in each of our eight cities, since that data isn't publicly aggregated at the city level anywhere we could confirm. And whether any individual lender has fully implemented the March 2026 Fannie Mae rule on your specific loan type as of today; DU 12.1 rolled out at the investor level, but adoption timing at the loan-officer level varies.

How We Work in the Sacramento Region

We're a licensed California general contractor, CA Lic. #1066117, with over 20 years of construction experience across the state and a 5.0-star Google rating. We have a project manager working the Sacramento and Davis region directly. We're not appraisers and we're not lenders, and we're not going to pretend otherwise or hand you a made-up value number to make a sales pitch land better. What we can do is build the ADU to a standard that holds up when an appraiser or a buyer actually looks at it, finished correctly, permitted correctly, and closed out correctly, which is most of what's within your control in this whole process. Learn more about our work in Sacramento and Davis.

Get a Real Number to Start From

The appraised value question doesn't have a clean answer until an appraiser is standing in front of your finished, permitted unit with actual comps in hand. The construction cost question does have an answer, and it's the one you actually control from day one. Call (530) 204-8294 to talk through your lot, or start with the ADU cost calculator at safewayremodel.com, about two minutes, no site visit required.

Frequently Asked Questions

Safeway Construction — CA Lic. #1066117 | 20+ years of California construction experience | 5.0-star Google rating | Serving Sacramento, Elk Grove, Davis, Folsom, Woodland, West Sacramento, Roseville, and Dixon.

Phone: (530) 204-8294

Related Guides

• ADU Financing in the Sacramento Region: 2026 Guide
• Davis ADU Rental Income 2026: Will It Actually Pay for Itself?
• Sacramento ADU Guide: Permits, Costs and EZPermit (2026)
• Davis ADU Guide: Permits, Costs & Free Plans (2026)
• Sacramento-Region ADU Property Tax Reassessment Guide (2026)