Appraisers pick comps by working backward from what has already closed — matching gross living area within a defensible range, matching condition and quality, matching features like a pool, and refusing to cross the invisible lines that separate one price tier from the next. Understanding how appraisers pick comps is the difference between a refinance that returns your capital and one that leaves $40,000 stranded in the deal.
Katya Borisova is a certified residential appraiser and an eight-property investor in the Phoenix area, which means she sees both sides of the same report — what the borrower is trying to accomplish and what the underwriter needs to approve it. Her rules below are the ones she gives investors and agents when they send her comps before an inspection.
This guide covers the square footage range to stay inside, what instantly kills a comp, why the one-mile rule is a myth, which improvements actually receive value, and how to build a co-living property that can still be appraised and refinanced.
Key takeaways
- Stay within 20–25% of your subject’s gross living area when picking comps. Appraisers may look wider, but investors who tighten the range make fewer valuation mistakes.
- Never cross a major street for a comp unless you know the area cold. A road can separate two entirely different price tiers, and using comps from the wrong side gets reports called back.
- There is no one-mile, three-month rule. Appraisers will go two, three or five miles for a genuinely comparable sale, so send the truly similar distant comp instead of the weak nearby one.
- Extra bedrooms do not add value because square footage is already adjusted for. Adding a bathroom to a 4/2 can add roughly $10,000 to $20,000 depending on house size.
- On co-living builds, skip true built-in closets in every room so space stays classifiable as office, dining or flex — a 7-bed/3-bath is far harder to appraise than a 5-bed with flex rooms.
From the Real Estate Pros Show
This article draws on an interview with Katya Borisova of AZ Appraisal Company on the Real Estate Pros Show, hosted by Cody Crabb.
The Comp Rules Appraisers Actually Use
Start with size. Borisova’s cheat sheet for investors: pick comparables within 20% — 25% at the outside — of the subject’s gross living area. Appraisers themselves will look at a wider band when the data forces it, but an investor estimating ARV should tighten the range, because a wide range is where optimistic math hides.
Then match the property, not just the numbers:
- Condition — a light cosmetic refresh is not comparable to a heavy remodel
- Quality — construction and finish level, not just year built
- Pool or no pool — if the subject has one, find comps that have one
The failure Borisova sees most often is investors pulling heavily remodeled comps, then executing a low-end remodel and expecting the number to hold. It does not. “Appraisers are well trained to see these things,” she says, “and we cannot manufacture value.”
That last point is the one worth internalizing. An appraiser looks backward. The report is built from sales that have already closed, in the condition those houses were actually in. Nothing about your intentions, your holding costs or your lender’s needs enters the analysis. If nothing in the market has closed at your target number in your subject’s condition, the number does not exist yet.
Borisova applies the same discipline to her own portfolio — she looks at what is listed around her properties and how those competitors are finished before deciding on scope. That single habit prevents both directions of error: under-improving against strong comps, and over-improving beyond what the neighborhood will support.
What Instantly Disqualifies a Comp
Two things kill a comp on sight: a location influence the subject does not share, and a major street between the comp and the subject.
Borisova’s example is a golf community. The subject sits inside the neighborhood on a standard interior lot. The investor pulls the four highest sales in the community — and every one of them fronts the golf course. Those are not comparables. They are evidence of a location premium the subject does not have.
The fix is paired analysis. Find two similar houses where the only meaningful difference is course frontage. If one closed $30,000 higher, you have just measured the premium, and you now know to strip it out rather than borrow it.
The street rule is less intuitive and more expensive. Early in her career, Borisova appraised a property north of a major road and selected every comp from south of it. The south side was a higher-value pocket. The lender caught it, the report came back, and she had to work through a reconsideration of value with a new comp set — which confirmed the callback was correct.
Her guidance to investors now: do not cross major streets. If you are not certain about the submarket, go a mile, a mile and a half, even two miles in the same direction rather than half a mile across a boundary. Roads frequently separate price tiers that look identical on a map and behave nothing alike in the data. “It’s just the street difference” is exactly how a report gets called back.
Folks like looking at super remodeled comps and then do a very low-end remodel and expect that the value will be there. Appraisers are well trained to see these things. And we cannot manufacture value.
— Katya Borisova, certified residential appraiser and investor, Phoenix, AZ
The One-Mile, Three-Month Myth
Appraisers are not confined to a one-mile radius or a 90-day window. This is probably the most common misconception Borisova hears from investors, and it costs them good comps.
“We look way over the one mile if necessary,” she says. “If we need to find a comparable that is a true comparable, we will go two miles, three miles, five miles, whatever is needed.” The driver is comparability, not distance. A genuinely similar sale three miles away in a similar submarket with the same influences is more useful than a marginal sale down the street.
What appraisers are actually trying to do is bracket the subject — surround it with sales above and below it on the key characteristics so the adjusted value lands inside a supported range rather than at the edge of the data. Unique properties, unusual layouts and specialty configurations are the cases that push the search radius outward, because there simply is not enough nearby data to bracket with.
The practical move for investors: when you send comps ahead of an appraisal, send the distant sale that truly matches your property rather than the nearby sale that merely matches your target number. Borisova asks agents and investors for their comps on every assignment and says plainly that many of them are not comparables at all. But if they are, she uses them — and she expects an explanation of what you looked at when you decided to buy or refinance.
Why Extra Bedrooms Add Nothing and Bathrooms Do
Bedroom count does not carry independent value in a residential appraisal, because the square footage those bedrooms occupy has already been adjusted for through gross living area. Adding a value line for bedroom count on top of that would be double-adjusting the same thing twice.
Borisova’s illustration: two four-bedroom, two-bath houses, one at 2,000 square feet and one at 2,500. There is an adjustment for the larger area — and appraisers do not adjust per square foot, they work off a threshold. But you cannot then also adjust because one house subdivided its space into more rooms.
There is a market logic underneath the methodology. Some buyers want more rooms because they have a large family. Others pay a premium for open space and higher ceilings. Neither preference is universal, so an appraiser cannot assume the market pays for partition walls. Framing a den into a seventh bedroom converts flexible space into a specialized configuration without creating any new square footage.
Bathrooms behave differently. Taking a 4/2 to a 4/3 adds a genuinely new function and, in Borisova’s experience, can add somewhere in the range of $10,000 to $20,000 depending on the size of the house. She is deliberately careful about quoting exact figures, and you should be too — the adjustment is market-specific and pulled from paired sales, not from a national rule of thumb.
The budgeting implication is direct. If your renovation plan is heavy on room count and light on baths, you are spending money the appraisal will not return.
Making Co-Living Properties Appraisable
The single most useful decision in a co-living build is not installing true built-in closets in every room. Once every room has a built-in closet, it reads as a bedroom, and a seven-bedroom, three-bath house is dramatically harder to appraise than a four- or five-bedroom with flex space. Keep rooms classifiable as an office, a dining room, or future assisted-living use and you preserve both the appraisal and your exit options.
The reason is buyer pool. Push the configuration far enough — Borisova points to six-bed, six-bath builds — and the only realistic buyer is another investor. When that happens, the appraiser is not going to hand back full value for all six bathrooms. The tools available are cost-to-cure treatment or simply withholding value from surplus fixtures, and either way the number lands below what the investor spent.
Written explanation matters as much as the number. Borisova builds detailed commentary into these reports specifically so the underwriter can understand what the property is and process the loan. Most appraisers decline co-living assignments outright — they do not understand the configuration or how to support it — which is why finding someone who does is worth the search.
One operating warning from someone running five co-living properties: when she entered, her market had roughly 70 rooms across fewer than ten properties. As more operators pile in, price per room is falling and rooms are harder to fill. The valuation problem is manageable. The occupancy and tenant-management problem is the one that breaks people, and it is getting harder, not easier.
Structuring the Buy So You Can Refinance Out
Structure the deal on the front end so the refinance returns your capital. Borisova credits this lesson to Ogi, the investor who helped her buy her first property, and it is how she acquired her entire portfolio — the same chunk of funds, recycled through deal after deal.
That only works if the ARV you underwrote is the ARV the appraiser supports, which means the renovation budget has to be set against real comps before you buy, not discovered afterward.
The mistake she made first, and sees constantly, is over-improvement. “You remodel the home like you’re going to live there,” she says of her first flip — a condo where she spent well past what the market would pay and walked away with $15,000. Greed and perfectionism produce the same outcome: budget blown, too much money left in the deal, no new capital created, and no next purchase.
Her closing advice is unglamorous and correct. If you are not confident in your own valuation, pay a few hundred dollars for an appraisal from someone who understands both the investment side and the appraisal side before you commit. Get the current value, get a supported view of the post-renovation value, and pick your exit strategy from there.
The math is obvious at low volume. At two deals a year, you are not going to develop appraiser-grade instincts through repetition. Five to seven hundred dollars of professional valuation on a deal that could strand tens of thousands in trapped equity is not an expense worth optimizing away.
Frequently asked questions
How close in square footage does a comparable need to be?
Stay within 20% of the subject’s gross living area, and 25% at the outside. Appraisers will look at a wider band when the available data requires it, but investors estimating ARV should tighten the range — a wide range is where wishful thinking hides.
Size alone is not enough. The comp also needs to match on condition, construction quality, and major features like a pool. A same-size house that was gutted to the studs is not comparable to one that received new paint and carpet.
Can an appraiser use a comp more than a mile away or older than three months?
Yes. The one-mile radius and 90-day window are misconceptions, not appraisal rules. Katya Borisova, who appraises in the Phoenix market, says appraisers will go two, three or five miles when that is what it takes to find a genuine comparable, especially for unique properties where there is not enough nearby data to bracket the subject.
The practical takeaway: send the appraiser a truly similar sale further out rather than a weak sale next door.
Does adding bedrooms increase an appraised value?
Generally no, because the square footage those bedrooms occupy is already captured in the gross living area adjustment. Adding a separate value line for bedroom count would double-adjust the same characteristic.
Bathrooms are different. Borisova says adding a bath to a four-bedroom, two-bath house can add roughly $10,000 to $20,000 depending on the size of the home, though she is careful not to treat that as a fixed figure — the adjustment is derived from local paired sales.
Why do most appraisers refuse co-living assignments?
Because comparable sales are extremely hard to find and the reports require substantial written support. A six-bed, six-bath co-living property has a buyer pool of essentially other investors, which means value on surplus bathrooms may be withheld or handled through a cost-to-cure approach — and the appraiser has to explain all of that clearly enough for an underwriter to process the loan.
Many appraisers simply do not know how to support the configuration, so they decline the assignment rather than risk the report.
Should I send my own comps to the appraiser before the inspection?
Yes, and Borisova actively asks for them. Send the comparables you used when you decided to buy the property or when you set your refinance target, along with what you looked at and why.
Do not assume they will be used. She notes that many of the comps agents and investors send are not truly comparable. But if they are good comps, they get used — and a strong comp you supply may be one the appraiser would not have found.
The bottom line
Before your next acquisition closes, rebuild your ARV using only comps that survive all four filters — within 20-25% of gross living area, matched on condition and quality, matched on major features, and on your side of every major street. If that exercise moves your number, your renovation budget needs to move with it.
