Comparable sales are the core of property valuation: if similar homes are selling for X, your home is worth approximately X, adjusted for differences. The skill is in selecting the right comps and making accurate adjustments--that's where appraisers earn their keep.
What Makes a Comparable Sale "Comparable"?
Not every recent sale in your area is usable. In fact, many aren't.
A comparable sale needs to be:
Similar Property Type: A condo isn't comparable to a single-family home. A townhouse isn't comparable to a detached house. Different products command different prices.
Similar Location: Generally, sales should be in the same neighborhood or very nearby. A home five miles away might be useful, but 15 miles away usually isn't. Market conditions vary significantly by location.
Recent Timing: Ideally, within 30-60 days of the subject property's appraisal date. Sales from six months ago can work if there aren't better options, but require seasonal and market adjustments.
Arm's-Length Transaction: Both buyer and seller were acting in their own interests, not under duress. A foreclosure sale, a quick estate liquidation, or a below-market family transaction don't represent market value.
Arms-Length Financing: The buyer used conventional financing (or cash). Sales with non-market financing distort value.
Competitive Market Sale: Buyer and seller had reasonable negotiating positions. A property that sold after 120 days probably went for less than one that sold in 14 days, all else equal.
How I Select My Comps
I typically need three comparable sales. Sometimes I use four or five to strengthen my analysis.
Here's my process:
Step 1: Search the Database: I pull MLS data for sold properties matching the subject's basic characteristics: property type, size, age, within 1-2 miles.
Step 2: Review Transaction Details: I eliminate sales that don't meet the "comparable" criteria. Foreclosures get questioned. Short sales get examined. Family transfers get noted and often excluded.
Step 3: Analyze Days-on-Market: A property that sold after 10 days suggests stronger demand than one that sold after 70 days. This matters because it indicates buyer competition.
Step 4: Verify Details: I call the listing agents and selling agents. I verify property specs, condition notes, and transaction circumstances. "As-is" sales are different from move-in ready.
Step 5: Physical Inspection: I drive by the comparable properties. I note their condition, lot size, view characteristics, and overall appeal relative to the subject property.
By the time I narrow it down, I have three rock-solid comparables with documented details.
The Adjustment Process
Now I have three comps that sold recently in similar neighborhoods. But they're not identical to the subject property. A comp might be 200 square feet larger, or have a updated kitchen, or be on a larger lot.
I adjust the comp's sale price to account for these differences:
Condition Adjustments: If a comp needed a new roof and the subject doesn't, I might adjust the comp's price upward (because the subject is better). If the comp had granite counters and the subject has laminate, I adjust the comp downward.
Condition adjustments are usually 2-8% of sale price, depending on the severity.
Size Adjustments: If a comp was 100 sq ft larger, I adjust its price downward based on a $/sq ft factor. In Orange County, that's currently $280-$400/sq ft depending on location and property type.
Quality Adjustments: An older, dated comp might need 5-10% adjustment if the subject is more updated. Ultra-high-end finishes might command 3-5% premiums.
Location/View Adjustments: A comp without a view that sold for $480,000 might need a 12-15% adjustment upward if the subject has a view. Location adjustments vary by specific neighborhood microdifferences.
Utility Adjustments: A comp on a busier street might be adjusted downward by 5-8% if the subject is on a quiet street.
Time Adjustments: If a comp sold three months ago and the market has appreciated 1.5%, I adjust the comp's price upward to reflect current market conditions.
Building the Value Range
After adjusting my three comparables, I get three adjusted values. In a typical appraisal:
- Comp 1 adjusts to $445,000
- Comp 2 adjusts to $442,000
- Comp 3 adjusts to $448,000
This gives me a narrow range ($442k-$448k) centered around $445,000. That's my estimated fair market value.
If my comparables adjusted to $420k, $445k, and $480k—a $60k range—I know something's off. I'd revisit my adjustments or question whether these properties are truly comparable.
When Comps Are Scarce
In slow markets, or for unusual properties, finding three good comparables is hard. I might adjust by looking at properties that sold 60-90 days ago, or from slightly farther away.
In these cases, I'm more conservative with my adjustments and more explicit about the limitations in the appraisal. The fewer rock-solid comparables available, the wider the margin of error.
Why Appraisers Aren't Just Using Averages
A common misconception: appraisers just find three comparable sales, average them, and done.
That underestimates the work. My adjustments are documented and defensible. I'm not guessing that the subject property's location is worth 8% more—I'm basing it on specific sales evidence.
Every adjustment should be traceable to market data or well-reasoned analysis.
Comparable Sales Are Reality
Here's why comparables matter: they represent actual market transactions. A home's appraised value isn't my opinion. It's market-derived data based on what informed buyers and sellers have actually agreed to.
That's the strength of the comparable sales approach. It's empirical. It's testable. It's defensible.
When someone asks "why did my home appraise at $445,000?" the answer is: "Three very similar homes sold recently for prices averaging $445,000 after adjusting for known differences."
That's not theoretical. That's real market evidence.
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Understanding your home's comparable sales? I can walk you through the analysis that supports your appraisal. Contact me to discuss your specific market.