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Illinois exam glossary

External obsolescence

The hardest losses are often the ones the owner cannot touch. A perfectly maintained building can lose value when traffic changes, a major employer closes, rents fall, or a neighboring use alters buyer behavior. The appraiser's job is to isolate that outside influence, measure what the market actually does, and deduct it only once.

Last updated: August 1, 2026

What does this exam area cover?

Short answer: External obsolescence is value loss caused by an influence outside the property or the owner's control. Locational causes include noise, traffic, access, and incompatible neighboring uses. Economic causes include oversupply, demand contraction, market-rent decline, regulatory burden, and industry change. The loss is generally incurable by the owner but can be temporary or permanent. It may be measured through paired sales, income-loss capitalization, market extraction, before-and-after evidence, or feasibility analysis.

Official section
National III: Valuation
Broker weight
8% of the national broker portion
Expected scored items
Valuation accounts for about 8 of 100 items

This guide follows the current Illinois appraiser statute and agency resources, USPAP access from The Appraisal Foundation, the PSI Illinois exam outline, and Fannie Mae neighborhood, cost, and adjustment guidance published through June 3, 2026, all checked through August 1, 2026. Fannie Mae's shopping-center example is an appraisal-consistency illustration, not a universal fixed deduction. External loss depends on actual market response, duration, rights, affected component, effective date, and whether another valuation input already captures the influence.

What is on the official outline?

Topic
Locate the cause
What to know
Outside property, off-site source, neighborhood, market area, regional economy, industry, law, infrastructure, adjoining use, public project, ownership control, internal design, physical condition, and causal evidence
Best exam move
Classify by the origin of the value loss, not merely by where the damage or price effect appears.
Topic
Identify locational influence
What to know
Highway, airport, rail line, commercial loading, landfill, power line, odor, noise, vibration, view block, access, traffic pattern, crime exposure, flood perception, and incompatible adjacency
Best exam move
Locational loss arises because market participants react to where the property sits relative to an outside influence.
Topic
Identify economic influence
What to know
Oversupply, rent decline, vacancy, employer closure, population change, industry contraction, interest-rate environment, regulatory change, tax burden, insurance cost, commodity cycle, demand shift, and property-type obsolescence
Best exam move
Economic obsolescence can affect many properties even when no single neighboring nuisance exists.
Topic
Define the affected property interest
What to know
Fee simple, leased fee, leasehold, land, improvements, going concern, tenant position, contract rent, market rent, use restriction, easement, mineral right, air right, and effective date
Best exam move
The same external event can affect land value, improvement utility, landlord income, and tenant interest differently.
Topic
Verify market recognition
What to know
Sale price, rent, vacancy, occupancy, concession, absorption, marketing time, listing history, buyer interview, tenant interview, broker interview, appeal, lender reaction, insurance, expense, and documented trend
Best exam move
An outside condition is not a measurable value loss until credible evidence shows market participants react to it.
Topic
Distinguish temporary and permanent
What to know
Construction period, closure date, lease term, moratorium, finite restriction, market cycle, expected recovery, permanent infrastructure, irreversible adjacency, duration, probability, and effective-date expectation
Best exam move
Do not capitalize one year's loss forever when credible evidence supports a limited duration.
Topic
Test subject-owner control
What to know
Boundary, ownership, easement, public authority, neighboring owner, private agreement, legal action, mitigation, sound wall, access change, landscaping, use conversion, relocation, and economic feasibility
Best exam move
Mitigation can reduce an effect, but the source remains external when the owner cannot remove the outside cause.
Topic
Use paired sales
What to know
Affected sale, unaffected sale, similar rights, date, location, site, design, quality, condition, income, transaction terms, feature isolation, repeated pair, percentage loss, and statistical support
Best exam move
A credible pair controls other differences before assigning the remaining price gap to the external influence.
Topic
Use rent and occupancy evidence
What to know
Market rent, affected rent, vacancy, collection, concession, renewal, tenant demand, operating expense, insurance, noise mitigation, downtime, stabilized NOI, and comparable lease
Best exam move
Translate the external influence into supported income and expense effects rather than assuming every rent gap has one cause.
Topic
Capitalize permanent income loss
What to know
Annual NOI penalty, overall rate, property interest, permanent expectation, direct capitalization, market rate, growth, risk, consistent income, value loss, allocation, and sensitivity
Best exam move
Under supported perpetual assumptions, external loss can equal annual NOI loss divided by an appropriate rate.
Topic
Discount temporary income loss
What to know
Annual loss, finite years, discount rate, present value factor, expected recovery, probability, timing, growth, construction completion, lease event, terminal condition, and sensitivity
Best exam move
Present-value each supported temporary loss rather than treating it as permanent.
Topic
Use market extraction
What to know
Sale price, land value, cost new, physical deterioration, functional obsolescence, improvement contribution, residual external loss, multiple properties, affected market, unaffected benchmark, and consistent assumptions
Best exam move
Residual external loss is reliable only when the cost, land, and other depreciation estimates removed first are credible.
Topic
Analyze feasibility
What to know
Market rent, construction cost, land value, entrepreneurial incentive, required return, development timing, absorption, residual land value, current use, alternative use, conversion, demolition, and economic viability
Best exam move
When market value cannot support current construction economics, external economic obsolescence may be part of the explanation.
Topic
Allocate land and improvement effects
What to know
Site value, location discount, improvement cost, rent loss, land-building ratio, market evidence, land residual, property total, affected component, sales comparison, cost approach, and no automatic allocation
Best exam move
Determine where the market loss is already captured before assigning another deduction to improvements.
Topic
Coordinate the sales comparison approach
What to know
Comparable from same influence, competing area, location adjustment, affected and unaffected sale, market area, neighborhood boundary, view, access, noise, transaction verification, support, and reconciliation
Best exam move
Comparables sharing the subject's external influence can reduce the need for a separate location adjustment but still require analysis.
Topic
Coordinate the income approach
What to know
Market rent, subject rent, vacancy, expense, capitalization rate, risk premium, terminal value, temporary loss, permanent loss, double counting, and stabilized assumption
Best exam move
Do not reduce NOI for the influence and also use a rate that includes the full same penalty without analysis.
Topic
Coordinate the cost approach
What to know
Replacement cost, physical loss, functional loss, external loss, land value, site improvement, total accrued depreciation, location influence, economic influence, remaining life, and reconciliation
Best exam move
The cost approach should tell the same external-influence story as the site, market, sales, and income sections.
Topic
Avoid protected-class proxies
What to know
Race, color, religion, sex, disability, familial status, national origin, demographic composition, coded language, property factor, market evidence, fair housing, objective description, and bias review
Best exam move
Describe and measure lawful property and market influences, not the protected-class identity of residents or buyers.
Topic
Document the loss
What to know
Source, distance, direction, intensity, affected area, property rights, duration, data, method, income, rate, comparable, allocation, assumption, uncertainty, effective date, and reconciliation
Best exam move
A credible conclusion explains what the influence is, who reacts, how long it lasts, how it changes value, and where the deduction appears.

Which distinctions produce the most mistakes?

Terms
External vs. functional obsolescence
Difference
External obsolescence originates outside the property or owner control. Functional obsolescence originates in internal design, feature, capacity, or utility.
Question cue
Outside source versus inside source.
Terms
External vs. physical deterioration
Difference
External loss comes from outside influence. Physical deterioration comes from wear, damage, age, or deferred maintenance in property components.
Question cue
Market or location cause versus material condition.
Terms
Locational vs. economic obsolescence
Difference
Locational obsolescence is tied to the property's setting or adjacency. Economic obsolescence comes from broader market, industry, legal, or economic conditions.
Question cue
Where it sits versus what the wider market is doing.
Terms
Incurable vs. permanent
Difference
Incurable means the subject owner cannot economically remove the cause. Permanent means the effect is expected to continue indefinitely or through the relevant life.
Question cue
Owner control versus duration.
Terms
Temporary vs. permanent loss
Difference
Temporary loss ends after a supported period or event. Permanent loss persists through the relevant investment or economic horizon.
Question cue
Finite penalty versus ongoing penalty.
Terms
Cause vs. mitigation
Difference
The cause is the outside influence. Mitigation is an on-site or off-site action that reduces its effect without necessarily removing the source.
Question cue
Origin of problem versus reduction of impact.
Terms
Market evidence vs. owner perception
Difference
Market evidence shows buyer, tenant, or investor reaction in price, rent, expense, occupancy, risk, or exposure. Owner perception alone does not quantify value loss.
Question cue
Observed reaction versus personal concern.
Terms
Paired-sale loss vs. income loss
Difference
Paired sales infer price reaction from controlled transactions. Income analysis measures the effect on rent, vacancy, expense, or NOI and converts that effect to value.
Question cue
Price comparison versus benefit-stream comparison.
Terms
Permanent capitalization vs. temporary discounting
Difference
Direct capitalization can model an ongoing stabilized loss. Present-value discounting models finite losses by timing each expected amount.
Question cue
Perpetual assumption versus finite schedule.
Terms
Land loss vs. improvement loss
Difference
Land loss changes the site value. Improvement external depreciation reduces the contribution of constructed improvements. One influence may affect both but must not be counted twice.
Question cue
Site component versus building component.
Terms
Neighborhood boundary vs. market area
Difference
A neighborhood is a local grouping. A market area is the region from which demand comes and where competition is located, potentially across neighborhood lines.
Question cue
Local boundary versus buyer competition.
Terms
External adjustment vs. external depreciation
Difference
A sales adjustment compares location or outside influence between subject and comparable. External depreciation is the cost-approach loss attributed to outside causes.
Question cue
Comparable-price line versus cost-new deduction.

The O-U-T-S-I-D-E audit

  1. Origin: identify the outside cause, location, distance, intensity, start date, legal or market event, affected property type, and whether the issue is local, regional, industry-wide, temporary, or permanent.
  2. User reaction: verify how buyers, tenants, investors, lenders, and insurers respond through price, rent, vacancy, concessions, expenses, capitalization rates, marketing time, use choice, and development feasibility.
  3. Time and control: determine what the subject owner can mitigate, what only a third party can change, the supported duration, expected recovery, probability, remaining economic life, and effective-date knowledge.
  4. Support the measurement: isolate paired sales, rent or NOI differences, market extraction, before-and-after evidence, feasibility results, direct capitalization, or discounted temporary losses with consistent rights and assumptions.
  5. Identify allocation: decide whether the influence affects land, improvements, or both, and trace where site value, sales adjustments, NOI, rates, cost depreciation, and risk already capture the penalty.
  6. Deduct once: prevent overlap among approaches and inputs, coordinate temporary and permanent methods, use objective lawful factors, and reconcile the loss with the total property value evidence.
  7. Explain: report the cause, evidence, market response, duration, method, allocation, uncertainty, assumptions, and consistency across the appraisal rather than relying on a label alone.
Question
Is the cause outside?
Evidence
Map, observation, law, infrastructure, market event
Common error
Calling an internal defect external
Question
Does the market react?
Evidence
Sales, rent, vacancy, expense, exposure, interviews
Common error
Assuming loss from appearance alone
Question
How long will it last?
Evidence
Project dates, lease term, forecasts, market recovery
Common error
Capitalizing temporary loss forever
Question
What is affected?
Evidence
Land, building, income, use, rights, buyer pool
Common error
Applying full loss to every component
Question
How is it measured?
Evidence
Paired sales, NOI, extraction, DCF, feasibility
Common error
Using an unsupported flat percentage
Question
Where is it captured?
Evidence
Site value, comp adjustment, NOI, rate, cost deduction
Common error
Double counting across approaches

How do the rules work in scenarios?

A home backs to commercial loading

Scenario: A residence backs to a shopping center's overnight delivery area. Verified paired sales indicate homes with the same exposure sell about $35,000 below otherwise similar quiet-location homes.

  1. The noise and activity source lies outside the residential property.
  2. Controlled sale evidence indicates buyer reaction.
  3. The appraiser must determine whether the site value or another comparison already captures the penalty before deducting it elsewhere.

Answer: Treat the supported market penalty as an external locational influence and prevent duplicate allocation.

An employer closure creates economic loss

Scenario: A major local employer closes, apartment vacancy rises sharply, and market rents decline across the submarket even though the subject remains well maintained.

  1. The property's physical condition has not caused the income change.
  2. The broader demand shock affects competing properties.
  3. The appraiser analyzes whether the decline is cyclical, temporary, or persistent and how current buyers price that risk.

Answer: Test external economic obsolescence through market income, sales, and duration evidence.

Capitalize a permanent NOI loss

Scenario: An off-site influence creates a supported permanent stabilized NOI penalty of $30,000 per year. The appropriate rate under the simplified facts is 10 percent.

  1. The annual effect is measured at the property-interest level.
  2. $30,000 / 0.10 = $300,000.
  3. The result assumes permanence and a consistent market-derived rate.

Answer: The indicated external-obsolescence amount is $300,000 under the stated assumptions.

A two-year construction impact is temporary

Scenario: A public project is expected to reduce NOI by $20,000 at each year-end for two years, after which access returns to normal. Use a 10 percent discount rate for the simplified question.

  1. Year 1 present value is about $18,182.
  2. Year 2 present value is about $16,529.
  3. Total indicated temporary loss is about $34,711, not $200,000 from permanent direct capitalization.

Answer: The rounded present value of the two-year loss is about $34,700.

A worn wall is not external

Scenario: A property's own sound wall has deteriorated and no longer blocks traffic noise as effectively as when new.

  1. Traffic is an outside source.
  2. The worn on-site wall is a physical condition that worsens exposure.
  3. The analysis may contain both physical deterioration and external influence, but each cause must be separated.

Answer: Do not label the wall's wear external; separate the physical repair from any remaining outside noise penalty.

The land value already captures location

Scenario: Vacant-land sales beside a rail corridor consistently sell below unaffected sites, and the subject site value is derived directly from those affected sales.

  1. The external location influence is already embedded in the site-value evidence.
  2. A full duplicate deduction from improvement cost can understate total value.
  3. The appraiser determines whether improvements suffer an additional loss beyond the lower land value.

Answer: Trace the influence through site value and deduct only any separately supported improvement loss.

High taxes require comparison, not assumption

Scenario: The subject's tax bill is higher than one nearby building's, but comparable investors price the submarket using NOI after actual taxes and similar overall rates.

  1. The tax effect may already reduce NOI.
  2. The cap rate may also reflect submarket risk and expectations.
  3. Another full external-obsolescence deduction could double count the burden.

Answer: Analyze comparative burden and trace where the effect is captured before adding any separate deduction.

What are the common exam traps?

Trap
Calling every outside condition a value loss
Correction
Verify market reaction in price, income, expense, occupancy, risk, use, or marketability.
Trap
Calling a worn component external
Correction
Physical condition remains physical deterioration even when an outside event originally caused the damage.
Trap
Calling a poor layout external
Correction
An internal design or utility problem is functional obsolescence.
Trap
Equating incurable with permanent
Correction
An owner may be unable to cure a temporary public construction impact that ends on a known date.
Trap
Capitalizing a finite loss forever
Correction
Discount supported temporary losses over their expected duration.
Trap
Using one flat location percentage
Correction
Derive the effect from relevant sales, rents, expenses, marketability, feasibility, and duration evidence.
Trap
Ignoring property rights
Correction
Fee simple, leased fee, leasehold, land, and tenant positions can experience the same event differently.
Trap
Deducting the whole property loss from improvements
Correction
Allocate supported effects between site and improvements and recognize where land value already captures location.
Trap
Reducing NOI and rate for the same full penalty
Correction
Coordinate income and capitalization assumptions to prevent double counting risk or loss.
Trap
Using unverified comp pairs
Correction
Control rights, date, transaction, location, site, building, condition, and income differences before isolating the influence.
Trap
Ignoring mitigation
Correction
Sound barriers, access changes, conversion, and design can alter the market effect even when the external source remains.
Trap
Treating all economic decline as property-specific
Correction
Separate broad market obsolescence from subject management, condition, lease, and operating issues.
Trap
Using protected-class composition
Correction
Analyze objective property and market factors, not race, religion, disability, familial status, national origin, sex, color, or proxies.
Trap
Ignoring effective-date knowledge
Correction
Value reflects information and expectations relevant to the assignment's effective date, not later hindsight automatically.
Trap
Letting approaches tell different stories
Correction
Site, neighborhood, sales, income, and cost analysis should recognize the influence consistently.

Can you answer these original practice questions?

These questions are original study items aligned to the published outline. They are not copied, recalled, or predicted PSI questions.

1. What causes external obsolescence?

  1. An influence outside the property or owner control
  2. Only internal layout
  3. Only roof wear
  4. Mortgage amortization
Show answer and explanation

Answer: An influence outside the property or owner control

The influence can be locational, economic, legal, infrastructure-related, or market-wide.

2. A nearby airport creates noise. Which category applies?

  1. External obsolescence
  2. Functional obsolescence
  3. Physical deterioration
  4. Tax depreciation
Show answer and explanation

Answer: External obsolescence

The source is off-site and outside the owner's practical control.

3. Which is an economic rather than locational influence?

  1. Market-wide oversupply of the property type
  2. Noise from an adjacent rail line
  3. Blocked view from a neighboring building
  4. Traffic beside one parcel
Show answer and explanation

Answer: Market-wide oversupply of the property type

Oversupply changes the broader supply-demand balance rather than arising from one adjacency.

4. Why is external obsolescence generally incurable by the owner?

  1. The cause lies outside the property or ownership control
  2. It always lasts forever
  3. It cannot be measured
  4. It affects only land
Show answer and explanation

Answer: The cause lies outside the property or ownership control

An effect can be temporary even when the subject owner cannot remove its source.

5. A permanent NOI penalty is $25,000 and the rate is 10 percent. What is the indicated loss?

  1. $250,000
  2. $2,500
  3. $25,000
  4. $2,500,000
Show answer and explanation

Answer: $250,000

$25,000 / 0.10 = $250,000 under the simplified permanent-loss assumptions.

6. How should a supported two-year loss generally be modeled?

  1. Discount the finite expected losses to present value
  2. Capitalize one year forever automatically
  3. Ignore timing
  4. Add it to land value
Show answer and explanation

Answer: Discount the finite expected losses to present value

The method should match the supported duration rather than assume permanence.

7. The site value already reflects rail-corridor influence. What must the appraiser avoid?

  1. Double counting the same full loss
  2. Analyzing the improvements
  3. Using market evidence
  4. Stating the effective date
Show answer and explanation

Answer: Double counting the same full loss

Only a separately supported additional improvement effect should be deducted after the site treatment is understood.

8. Which method can reveal external price reaction?

  1. Paired sales with other differences controlled
  2. Original construction cost only
  3. Mortgage balance
  4. Tax basis alone
Show answer and explanation

Answer: Paired sales with other differences controlled

The pair must isolate the outside influence rather than attribute an uncontrolled price difference to it.

9. Which statement about external obsolescence is correct?

  1. It can be temporary even when the owner cannot cure it
  2. It always affects improvements only
  3. It always uses one national percentage
  4. It is the same as poor layout
Show answer and explanation

Answer: It can be temporary even when the owner cannot cure it

Curability concerns control and economics, while duration concerns how long the effect is expected to last.

10. What does current Fannie Mae guidance illustrate with a home backing to a shopping center?

  1. External depreciation should be consistent with the site and neighborhood analysis
  2. Every such home loses the same amount
  3. The property cannot secure a loan
  4. The issue is functional obsolescence
Show answer and explanation

Answer: External depreciation should be consistent with the site and neighborhood analysis

The example supports appraisal consistency, not a universal deduction or eligibility outcome.

How should you study this area?

Session
Session 1
Focus
Locate the cause
Proof you are ready
Classify 50 conditions as physical, functional, locational external, or economic external and state who controls the source.
Session
Session 2
Focus
Prove market reaction
Proof you are ready
For 20 outside influences, identify sale, rent, vacancy, expense, rate, marketability, use, feasibility, or risk evidence needed to prove impact.
Session
Session 3
Focus
Model duration
Proof you are ready
Classify 20 losses as temporary, permanent, or uncertain and select direct capitalization, DCF, or qualitative treatment with reasons.
Session
Session 4
Focus
Measure the loss
Proof you are ready
Complete eight paired-sale, eight NOI-capitalization, eight temporary-present-value, and six market-extraction cases.
Session
Session 5
Focus
Allocate and de-duplicate
Proof you are ready
Audit 20 cases across site value, comp adjustments, NOI, cap rate, cost depreciation, and feasibility to identify where the influence is already captured.
Session
Session 6
Focus
Run O-U-T-S-I-D-E
Proof you are ready
Write two complete external-obsolescence analyses, reconcile them with all approaches, then score at least 90 percent and explain every miss.

Do not count recognition as mastery. Close the notes and explain the rule, apply it to a new fact pattern, and identify why each distractor fails.

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Questions students ask about External Obsolescence: Illinois Exam Guide

What is external obsolescence in real estate?

External obsolescence is a loss in property value caused by an influence outside the property or outside the owner's practical control. It can be locational, such as airport noise or an incompatible adjacent use, or economic, such as market oversupply, employment contraction, rent decline, or a regulatory burden affecting the market.

What is an example of external obsolescence?

A home that backs to a noisy commercial loading area may sell for less than otherwise similar homes in quieter locations. Current Fannie Mae cost-approach guidance uses a property backing to a shopping center as an example where the lender should expect external depreciation analysis to be consistent with the site or neighborhood description.

Is external obsolescence always incurable?

It is generally considered incurable by the property owner because the cause lies outside the property or ownership control. The influence can still be temporary or later removed by market change, public action, or a third party. Incurable describes the subject owner's inability or economic power to cure it, not necessarily an effect that lasts forever.

What is locational obsolescence?

Locational obsolescence is external value loss tied to the property's immediate or broader location, such as traffic, noise, view obstruction, incompatible neighboring use, poor access, or environmental stigma. The same source can affect land and improvements, so the analyst must avoid deducting the full effect twice.

What is economic obsolescence?

Economic obsolescence is external loss caused by broader market, industry, legal, or economic conditions. Examples can include oversupply, falling market rents, employer closure, reduced demand for a property type, regulatory change, unusually high property burdens, or a mismatch between current development and market feasibility.

How is external obsolescence measured?

Common methods include paired sales, market extraction, capitalization of supported rent or NOI loss, before-and-after analysis, rent and occupancy comparisons, and feasibility analysis. The method must match the cause, duration, property interest, affected component, effective date, and available evidence.

Can external obsolescence be temporary?

Yes. A temporary construction closure, short-term oversupply, limited industry disruption, or finite rent restriction can create a time-limited loss. A permanent capitalization model can overstate temporary loss. The analyst should model the supported duration and timing, potentially using present value rather than capitalizing one year's penalty forever.

Is a bad roof external obsolescence?

No. A worn or damaged roof is physical deterioration because the cause is the condition of the property itself. A roof design that performs poorly relative to market expectations may also involve functional obsolescence. Damage caused by an external storm is still observed physical damage once it affects the roof, although insurance and event analysis may be separate.

Does a high property tax automatically create external obsolescence?

No. The analyst must determine whether the burden is unusual relative to competitive properties, whether buyers or tenants react, whether rent or price absorbs it, and whether it is already reflected in land value, operating expenses, capitalization rate, or comparable sales. An expense difference cannot be deducted again if the method already captures it.

How does external obsolescence affect the cost approach?

It is one component of accrued depreciation deducted from improvement cost new. The analyst first determines whether the external influence affects the land, improvements, or both, then coordinates the land valuation and improvement deduction. A location penalty already captured in site value should not be fully deducted again from improvements.

Are these official PSI questions or an appraisal?

No. The questions are original, and primary sources were checked through August 1, 2026. This page is exam education, not an appraisal, environmental assessment, engineering report, land-use opinion, or damages study. Actual loss analysis requires verified property, market, legal, environmental, income, cost, duration, allocation, and effective-date evidence.

Primary sources

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