What Is the Cost Approach to Value?
Bob Becker explains that the cost approach evaluates the property by calculating the cost to replace or reproduce it, then deducting depreciation to reflect its current state. This method looks closely at the specific elements of the property — such as materials, design, and structure — to determine its present-day value.
He notes that depreciation includes physical, functional, and external forms:
- Physical depreciation comes from wear and tear, like roof or parking lot deterioration.
- Functional obsolescence occurs when a property lacks modern features that are now standard, such as elevators in multi-story buildings.
- External obsolescence stems from outside factors, such as noise pollution or environmental issues that affect desirability or income potential.
When Is the Cost Approach Most Useful?
The cost approach is most persuasive in special-use properties that rarely sell in the open market — for example, schools, libraries, and certain public facilities. These types of assets lack reliable market comparisons, making replacement cost analysis the most logical valuation method.
Becker often applies this approach to private and public schools, library districts, and unique agricultural structures where comparable data is limited.
Challenges in Applying the Cost Approach
One of the biggest challenges is accurately estimating land value, particularly in areas where land sales are scarce. In those cases, appraisers may rely on older sales data, trend it forward, or use extraction methods to derive land value from nearby property sales.
Quantifying depreciation is another hurdle. Environmental or external market factors can affect how much value is lost, and overlooking these details can lead to inaccurate valuations.
How External Factors Impact Value
Nora Devine recalls working on an office building near O’Hare Airport that suffered from extreme airplane noise due to a new runway. The upper floors remained vacant because of constant vibration and noise — a textbook case of environmental obsolescence.
Becker agrees, noting that such examples demonstrate how uncontrollable external conditions can directly reduce a property’s value, even when the structure itself is sound.
Common Misconceptions About the Cost Approach
A frequent misconception is that the cost approach always produces the highest value, or that it’s irrelevant in property tax appeals. Becker clarifies that when properly performed, the cost approach should align closely with the sales and income approaches.
If one method produces a drastically different result, that signals a potential inconsistency in the data or assumptions used. Ideally, all three valuation methods should support a consistent picture of value.
Why Downstate Illinois Relies More on the Cost Approach
Becker explains that jurisdictions south of I-80 often depend heavily on the cost approach due to limited sales data and smaller commercial markets. Budget constraints may prevent local assessors from investing in mass appraisal systems or data subscriptions, leaving the cost method as the most practical tool available.
He emphasizes that even when the cost approach isn’t the final reconciliation method, it provides valuable insight for assessors. It helps them understand functional and external depreciation that may not appear in mass appraisal models.
Data Limitations South of I-80
Nora points out that commercial databases like CoStar and Crexi are often incomplete for downstate Illinois. Becker agrees, saying this is largely due to brokers not inputting their transactions into national systems and instead relying on local MLS listings. As a result, downstate appraisers must depend on a mix of local data, relationships, and professional judgment.
Keeping Up with Fluctuating Construction Costs
Since the pandemic, construction costs have fluctuated dramatically. Becker believes that Marshall & Swift Valuation Service does a decent job keeping up with monthly updates, but many assessment offices do not.
He explains that some counties only update their cost manuals every four to six years, relying on multipliers to adjust for inflation — a method that may not fully reflect current market realities.
How Appraisers Prepare for Hearings on the Cost Approach
When preparing for litigation or tax hearings, Becker focuses heavily on two key areas:
- Land valuation methods — ensuring the sales data and adjustments are defensible.
- Building quality ratings — understanding how “average,” “good,” or “excellent” classifications are defined in the cost manual and justifying those designations clearly.
He adds that while the rest of the cost approach tends to be straightforward, defending quality grading and depreciation analysis often becomes the center of debate during cross-examination.
Final Thoughts
Nora Devine closes the discussion by emphasizing the importance of understanding how each valuation method works and when to apply them. The cost approach to value, though sometimes underestimated, remains a vital tool in ensuring fair property assessments across Illinois.
For property owners facing complex commercial tax appeals, Devine Law Group helps identify risks and uncover opportunities for property tax savings.
Visit: devinelawgroup.com For expert property appraisal services, contact Bob Becker at rdbeckervaluation.com.
Stay tuned for more episodes of Divine Intervention: Shedding Light on Illinois Property Tax.