How Do Appraisers Choose Comparable Sales? Why the House Next Door May Not Be the Best Comp
- Laura Cade
- Aug 26
- 7 min read
One of the most common questions homeowners ask after receiving a real estate appraisal is:
“Why didn't the appraiser use the house that sold down the street?”
It is a fair question.
If a home in your neighbourhood recently sold for a certain price, it can seem logical that it should be one of the most important properties used to determine the value of your home.
But proximity is only one consideration.
Choosing comparable sales, often called “comps,” is one of the most important parts of the real estate appraisal process. A professional appraiser looks for properties that provide meaningful evidence of how the market would likely react to the subject property.
Sometimes the best comparable is next door.
Other times, a property several streets away, or even in another competing neighbourhood, may provide much better evidence.
Here is how appraisers actually choose comparable sales and why the closest sale is not necessarily the best one.
What Is a Comparable Sale?
A comparable sale is a property that has sold and shares relevant characteristics with the property being appraised.
Appraisers analyze comparable properties to understand how buyers have been reacting to properties similar to the subject.
The goal is not to find three houses that look identical.
In many markets, that would be impossible.
Instead, the appraiser looks for the most relevant available market evidence and then analyzes important differences between the comparable properties and the subject.
Depending on the property, these differences may include:
• Location
• Property type
• Lot size
• Building size
• Age
• Quality of construction
• Condition
• Renovations
• Bedroom and bathroom count
• Basement finish
• Garage and parking
• Waterfront or views
• Outbuildings
• Secondary units
• Site characteristics
• Market conditions at the time of sale
The importance of each characteristic varies depending on the property and the behaviour of buyers in that particular market.
1. Location Is Important, But Distance Isn't Everything
Appraisers generally want to find comparable properties within the subject property's competitive market area.
However, that does not necessarily mean choosing the three geographically closest sales.
Imagine two houses are located only a few blocks apart.
One is on a quiet residential street overlooking a park.
The other fronts a busy arterial road.
Although they are physically close, buyers may view those locations differently.
The same can happen when properties are separated by school districts, waterfront exposure, neighbourhood boundaries, commercial areas or other features.
The question isn't simply:
“How close is this property?”
The more useful question is:
“Would a typical buyer considering the subject property also have considered this property?”
That distinction is extremely important in appraisal analysis.
2. Property Type Matters
A detached home is generally best compared with other detached homes when sufficient market evidence exists.
The same principle applies to semi-detached homes, townhouses, condominiums, multi-residential properties and other property types.
For example, a beautifully renovated townhouse may have sold for more than an older detached home nearby.
That does not automatically make the townhouse the best comparable for the detached property.
The markets for those two property types may behave differently.
An appraiser considers how buyers perceive and price the particular property type being valued.
3. Size Is More Complicated Than Price Per Square Foot
Homeowners frequently calculate value by dividing a sale price by the home's square footage.
Price per square foot can be useful as one analytical tool, but residential properties are rarely valued by simply multiplying a square-foot rate by the subject's size.
Why?
Because the sale price includes much more than the building.
It reflects the land, location, condition, quality, garage, basement, site improvements and many other characteristics.
Two 2,000-square-foot houses can therefore have significantly different market values.
Appraisers analyze building size in conjunction with the entire property rather than relying solely on a price-per-square-foot calculation.
4. Age Doesn't Tell the Whole Story
Suppose your home was constructed 40 years ago.
Does that mean the best comparable must also be exactly 40 years old?
Not necessarily.
Effective age and overall condition can sometimes be more meaningful than chronological age alone.
A well-maintained older property that has undergone extensive modernization may compete differently than another property built during the same period that retains most of its original finishes.
Appraisers consider how buyers respond to those differences.
5. Renovations and Condition Can Make a Major Difference
This is one of the biggest reasons homeowners sometimes disagree with the comparable sales used in an appraisal.
Consider two otherwise similar houses.
One has a recently renovated kitchen, updated bathrooms, newer flooring and modern finishes.
The other requires substantial updating.
A buyer is unlikely to view those properties as equivalent simply because they have the same square footage and are on the same street.
The appraiser therefore considers the condition and quality of the comparable properties relative to the subject.
Importantly, renovation cost and contributory market value are not necessarily the same thing.
Spending money on an improvement does not automatically increase market value by the same amount.
The appraiser looks to market evidence to determine how buyers appear to recognize those improvements.
6. Lot Characteristics Matter Too
The house isn't the only thing being appraised.
The land can be an important component of value.
An appraiser may consider:
• Lot dimensions
• Overall site area
• Corner versus interior location
• Topography
• Privacy
• Waterfront exposure
• Views
• Road frontage
• Development potential
• Access
• Zoning and permitted uses
This becomes particularly important when appraising rural properties, waterfront homes, large lots and development land.
Two houses may be physically similar while sitting on dramatically different sites.
7. Garages, Basements and Other Improvements Matter
A property with a double attached garage may compete differently from a similar home with no garage.
Likewise, buyers may recognize differences between properties with:
• Finished and unfinished basements
• Walkout basements
• Additional bathrooms
• Pools
• Workshops
• Detached garages
• Barns
• Secondary units
• Significant landscaping or site improvements
Appraisers consider whether these features have a measurable influence on buyer behaviour in the subject's market.
8. The Sale Date Matters
Real estate markets change.
A property that sold recently may provide stronger evidence of current market conditions than an otherwise similar property that sold considerably earlier.
However, the newest sale is not automatically the best comparable either.
An older sale that is exceptionally similar to the subject may still provide useful evidence.
The appraiser must consider both comparability and market timing.
Where market conditions have changed between the comparable's sale date and the appraisal's effective date, that change may also need to be considered in the analysis.
9. Why Didn't My Appraiser Use the Highest Sale?
Another common question is:
“A house nearby sold for much more. Why wasn't it used?”
The answer may be that the higher-priced property wasn't sufficiently comparable.
Perhaps it was:
• Significantly larger
• Extensively renovated
• On a superior lot
• In a different neighbourhood
• A newer home
• Waterfront
• Equipped with superior improvements
• Not an arm's-length transaction
• Outside the relevant market period
An appraisal should not be designed around finding sales that support the highest possible value.
The objective is to identify relevant market evidence and develop an independent, well-supported opinion of value.
10. Why Appraisers Make Adjustments
Comparable properties are rarely identical to the subject.
That's why appraisal analysis may include adjustments.
If a comparable has a feature that the market recognizes as superior or inferior to the subject, the appraiser may account for that difference.
The important point is that appraisal adjustments should not simply be arbitrary amounts assigned to every feature.
Professional appraisal analysis considers available market evidence and how buyers appear to react to property differences.
After the adjustments and overall analysis are completed, the appraiser considers the relative strengths and weaknesses of the comparable sales when arriving at the final value conclusion.
What Makes a Really Good Comparable?
There isn't one universal formula.
A strong comparable is generally one that provides meaningful evidence of how buyers would likely react to the subject property.
For a typical subdivision home, there may be several highly similar recent sales nearby.
For a unique property, the search can become much more complicated.
Rural estates, waterfront homes, custom houses, commercial buildings, agricultural properties and properties with unusual improvements may require the appraiser to expand the search area or consider older transactions.
The goal remains the same:
Find the most relevant market evidence available.
Why Three Houses on the Same Street Can Have Different Values
This is something homeowners sometimes find surprising.
Imagine three houses located beside one another.
From the street, they appear almost identical.
But one has been completely renovated.
Another has an unfinished basement and original interior.
The third has a larger lot, double garage and superior outdoor improvements.
Their addresses may be only metres apart, yet buyers may be willing to pay different
amounts for each property.
That's why professional appraisal involves much more than looking at nearby sale prices.
The appraiser has to understand what actually made those properties different.
Can You Give Your Appraiser Comparable Sales?
Absolutely.
If you know about a recent transaction you believe is particularly relevant, you can provide that information to your appraiser.
The appraiser can then research the property and determine whether it is relevant to the assignment.
Providing a potential comparable doesn't mean it will necessarily be used, but additional market information can be helpful.
The Bottom Line
Comparable sales are one of the most important components of residential real estate valuation, but choosing them involves much more than finding the closest houses that recently sold.
A professional appraiser considers location, property type, size, condition, quality, site characteristics, improvements, market timing and numerous other factors before deciding which transactions provide the most meaningful evidence.
That is also why two appraisals don't necessarily contain exactly the same comparable sales.
Appraisal is an analytical process.
The objective is not to find a property that sold for the number someone wants.
It is to examine the market evidence objectively and develop a credible, well-supported opinion of value.
Need a Professional Real Estate Appraisal?
Cade Appraisals provides independent residential and commercial real estate appraisal services for homeowners, lenders, lawyers, accountants, executors, investors and other clients.
Our services include financing and refinancing appraisals, estate and probate valuations, divorce and matrimonial appraisals, retrospective appraisals, capital gains valuations, pre-listing and private-sale appraisals, litigation support, construction and progress inspections, market rent studies and other specialized valuation assignments.
Have Questions About Your Property’s Value?
Every property is different, and selecting the right comparable sales is only one part of developing a well-supported opinion of market value. If you need an independent real estate appraisal for financing, estate planning, divorce, taxation, litigation, a private sale or another purpose, Cade Appraisals can help.
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