Real Estate Salesperson · Property value and appraisal · 7 min read
Cost Approach and Depreciation
- Explain the cost approach formula, its underlying principle of substitution, and the property types for which it is most and least reliable.
- Differentiate between reproduction cost and replacement cost, direct and indirect costs, and the four methods used to estimate construction expenses.
- Analyze the three types of accrued depreciation, physical deterioration, functional obsolescence, and external obsolescence, and determine whether each is curable or incurable.
The Cost Approach Framework and When It Is Applied
The cost approach calculates property value by adding the estimated land value to the depreciated cost of all improvements. In real estate practice, salespersons working under a supervising broker will recognize that this valuation method is grounded in the principle of substitution. This economic principle holds that an informed buyer will pay no more for a property than the cost to construct an equivalent substitute.
Because this approach relies heavily on calculating current construction expenditures, the cost approach is highly reliable when evaluating newly constructed buildings. For a brand-new home or building, accrued depreciation is minimal and construction costs are easily documented. Conversely, the cost approach is generally least reliable for older structures because estimating accrued depreciation accurately is difficult and subjective as materials and components age.
In daily real estate practice, the sales comparison and income capitalization approaches require active market transactions or rental revenue data. When those data sources are unavailable, the cost approach is often useful for special-purpose or unique properties, such as churches and schools. Because comparable sales and income data may be scarce for special-purpose properties such as churches and schools, the cost approach can be useful: estimate the land value and the current cost of the improvements, then deduct applicable accrued depreciation; the result is a value indication, not an objective measure of market value.
Common mistakes
- Confusing reproduction cost with replacement cost by assuming they are interchangeable; reproduction cost refers to building an exact replica with identical or closely similar materials (ideal for historic properties), whereas replacement cost refers to constructing an improvement of equal utility using modern materials and design standards.
- Attempting to apply depreciation to land in the cost approach formula; raw land never depreciates, even though its market value may fluctuate over time, while site improvements and buildings do depreciate.
- Classifying external obsolescence as curable; because external obsolescence is caused by adverse factors outside the property boundaries, such as off-site industrial odors, airport noise, or local factory shutdowns, it is beyond the property owner's control and almost always incurable.
- Dividing chronological age rather than effective age by total economic life when using the economic age-life method; effective age accounts for remodeling and maintenance and must be used to calculate the depreciation percentage.
Key points
- The cost approach estimates value by adding the estimated land value to the depreciated cost of all improvements, relying directly on the economic principle of substitution.
- The cost approach is highly reliable for newly constructed buildings and special-purpose properties like churches and schools, but it is generally least reliable for older structures due to the difficulty of estimating accrued depreciation.
- Land is always appraised separately (typically via the sales comparison approach assuming it is vacant and at highest and best use) and is never depreciated, whereas site improvements like fences and driveways are subject to depreciation.
- Construction expenditures are divided into direct costs (materials, labor wages, equipment) and indirect costs (permits, architectural fees, financing interest), and they are estimated using the square-foot, unit-in-place, quantity survey, or index methods.
- Accrued depreciation is the loss in value from all causes (cost new minus contributory value), whereas accounting depreciation allocates asset cost over a prescribed useful life.
- Depreciation stems from physical deterioration (wear and tear, deferred maintenance), functional obsolescence (internal design flaws, superadequacies, poor floor plans), and external obsolescence (off-site locational, zoning, or economic nuisances, which are almost always incurable).
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Sample lesson: Market Value, Price and the Characteristics of ValueOriginal lesson written for Real Estate Salesperson practice · updated October 15, 2026. Exam names are trademarks of their owners; tests.global is not affiliated with them.