Comparable sales--recent sales of similar homes nearby--are the foundation of home appraisals. I select comps that match your home's location, size, age, condition, and features, then adjust for differences to arrive at your home's market value.
What Makes a Sale "Comparable"
A comparable (or "comp") has to match your home across several dimensions:
Location — The comp should be in the same neighborhood or a very similar neighborhood. Orange County neighborhoods are highly specific. A home in Newport Beach isn't comparable to a home in Santa Ana, even if they're the same size. Geography matters more than anything.
Property type — Single-family homes compare to single-family homes. Condos compare to condos. You can't appraise a condo by comparing it to a house.
Size — The comp should be within 300-400 square feet of your home. If your home is 2,000 square feet and my comp is 1,500, I need to adjust. Big adjustments are less reliable.
Age — The comp should be built within 10-15 years of your home. A 1970s home isn't directly comparable to a 2005 home, even in the same neighborhood. I can adjust, but the adjustment is big.
Condition — The comp should be in similar condition. If mine is a model home and yours needs a roof, that's a significant adjustment.
Recent sale — The comp should have sold within 3-6 months ideally. Old sales (a year ago) are less relevant because the market is moving fast.
Finding Comps
I use multiple sources:
MLS data — Multiple Listing Service records show homes that sold through real estate agents. This is my primary source.
County records — For sales that weren't through agents (FSBO—For Sale By Owner), I check county assessor records.
Public records — Sales data is public information. I can look at what homes actually sold for.
Knowledge of the market — After 40+ years appraising in Orange County, I know the neighborhoods. I know which neighborhoods have similar demographic appeal, similar commute times, similar amenities.
Analyzing Comps
Once I have three to five good comps, I analyze them systematically.
Let's say I'm appraising a 2,000 sq ft home built in 2000 in Huntington Beach. Here are my three comps:
Comp 1: 1,950 sq ft, built 2000, sold 4 months ago for $865,000
Comp 2: 2,050 sq ft, built 1998, sold 2 months ago for $850,000
Comp 3: 1,900 sq ft, built 2002, sold 3 months ago for $885,000
Now I adjust:
Comp 1: Slightly smaller (50 sq ft). Adjust down $2,000. Adjusted value: $863,000
Comp 2: Slightly larger (50 sq ft), older (2 years). Adjust down $5,000 total. Adjusted value: $845,000
Comp 3: Slightly smaller (100 sq ft), newer (2 years). Adjust down $3,000. Adjusted value: $882,000
My adjusted comp values cluster at $845,000-$863,000. The subject property's value is probably in that range. Maybe $855,000 as a mid-point.
How I Adjust
Adjustments come from market data. I look at recent sales to determine: how much does each additional square foot cost? How much does building year matter? How much does a garage or pool matter?
In Huntington Beach in 2007, I know:
- Each additional square foot costs roughly $400-450
- A 2-year age difference is worth $3,000-5,000
- A pool adds $15,000-25,000 (depending on size)
- A garage vs. no garage is $12,000-18,000
These numbers come from actual market sales. I'm not guessing.
What If Comps Don't Exist?
Sometimes I can't find perfect comps. Maybe the neighborhood is new, or your home is unique, or the market is moving so fast comps are stale.
In that case, I might use the cost approach (land value + replacement cost of structure) as a cross-check. Or I might use fewer comps and make larger adjustments.
In 2007, with the market moving so fast, I've had to use comps from 6-8 months ago because nothing closer exists. I then adjust for market appreciation that happened during those months.
Red Flags in Comp Analysis
Some things make comps less reliable:
Distressed sales — A foreclosure or short sale sells for less than market. I can't use it as a comp for a normal sale.
Non-arm's length sales — A sale between family members, or a corporate transfer where price doesn't matter. These don't reflect market value.
Extreme adjustments — If I have to adjust a comp by more than 10-15%, it's not really comparable. Better to find a different comp.
Very old sales — In a fast market, sales from a year ago are unreliable. The market changes.
Unique properties — If your home is truly one-of-a-kind, comps are hard. Luxury homes, horse properties, waterfront homes—these need specialized comps.
Market Trends
I also look at trends in the comp sales. Are the most recent sales higher or lower than sales from 6 months ago? Is the market appreciating or declining?
In early 2007, the most recent comps are selling for 2-4% more than older comps. That tells me the market is still appreciating, just more slowly than in 2006.
Why This Matters to You
When you get an appraisal, the comp analysis is where my conclusions come from. If you want to understand your appraisal, ask to see the comps.
Are they really similar to your home? Are the adjustments reasonable? Do the adjusted values cluster around my final value?
If something looks off, you can ask about it. Good appraisers are happy to explain their comp selection and adjustments.
Bottom Line
Comparable sales analysis isn't just grabbing four random sales. It's systematic, data-driven, and based on actual market transactions.
That's why appraisals using the sales comparison approach are reliable. The methodology is sound, the evidence is real, and the conclusions are defensible.
That's also why I can stand behind my appraisals. They're not opinions—they're data-based conclusions.