4.2 Highest and Best Use as Vacant

The “As Vacant” Question

AQB ECO I.i Determination of highest and best use explicitly includes analysis as vacant and as improved. These are related but not identical conclusions. Highest and best use as vacant answers: If this land were vacant and available for its appropriate use as of the effective date, what use would market participants put it to? That conclusion identifies the ideal improvement (or ideal land use program) and underpins site value.

Even when a building stands on the property, appraisers still develop an as-vacant conclusion because:

1. Land value in the cost approach is typically the value of the site under HBU as vacant.
2. Demolition decisions compare the improved property’s value to vacant-site value net of demo cost.
3. Consistent use requires knowing the land’s productive potential separate from a possibly obsolete building.
4. Market participants buying for redevelopment underwrite the site as if the building will be removed.

Critical mindset: “As vacant” is an analytical premise, not a claim that the lot is empty today. It is the same intellectual move as asking what a cleared site would be worth and how it would be used.

Ideal Improvement Concept

The ideal improvement is the improvement (or development program) that satisfies the four tests and produces the maximum residual value to the land. It is “ideal” relative to market demand and site capacity, not relative to an architect’s dream or the owner’s taste.

Attributes of an ideal improvement typically specify:

• Use type (for example, 12-unit garden apartment, single-family residence, neighborhood retail, industrial flex)
• Scale and intensity (units, square feet, stories, FAR utilization)
• Quality and class consistent with the market (not super-adequate finishes the neighborhood will not pay for)
• Timing (immediate development vs. held vacant for a short speculative period when supportable)
• Tenant/user orientation when relevant (owner-user vs. investment rental product)

The ideal improvement is the benchmark for functional obsolescence later: existing buildings are judged partly by how far they deviate from what the market wants on that site now.

Land as If Vacant: Analytical Steps

A defensible as-vacant HBU analysis generally follows this sequence:

1. Describe the site — size, frontage, topography, utilities, access, flood/environmental issues, linkages.
2. Inventory legal constraints — zoning, overlays, private restrictions, easements, nonconformity rules (if any structure is ignored for the vacant premise).
3. List candidate uses that are reasonably probable given market demand (not an endless catalog of every code-permitted use).
4. Apply Test 1–2 — eliminate legally unallowable and physically impossible candidates.
5. Test feasibility — for each remaining use, estimate development cost, timing, revenue/value on completion, and whether residual land value is positive/adequate.
6. Select maximally productive use — highest residual land value wins.
7. State the ideal improvement clearly enough that a reader can see density, quality, and use type.
8. Estimate land value under that use when the assignment requires it (sales comparison of sites, extraction, residual, etc.—detailed methods appear in the land valuation chapter).

Candidate Use Filtering Example

Site: 20,000 sq ft lot on a collector street in a growing suburb; zoned for single-family or duplex; multifamily requires rezoning rarely granted on this block; soils and utilities fine; market strongly supports 3-bedroom homes in the $450,000 range; duplex residuals slightly lower; speculative office not permitted.

• Legal survivors: single-family, duplex.
• Physical: both possible.
• Feasibility: both show positive residuals given current prices and build costs.
• Maximum productivity: single-family residual exceeds duplex residual on this block → HBU as vacant = single-family residence (market-standard three-bedroom product) as the ideal improvement.

If a stem says multifamily is allowed by right and residuals dominate, the ideal improvement flips—legal capacity plus market demand, not appraiser preference.

Residual Land Value Logic

Residual land value is the amount a developer can pay for the site after satisfying costs and required returns for the ideal (or tested) improvement.

Simplified structure:

Land residual ≈ Market value of completed property − Hard costs − Soft costs − Entrepreneurial incentive − Other required project costs (and sometimes financing residual structures depending on method)

Equivalently: after the agents of production other than land are paid their market returns, what remains for land?

Numeric micro-example (exam arithmetic level):

• Estimated market value of completed duplex: $720,000
• Total development cost excluding land (hard + soft + entrepreneurial incentive): $540,000
• Demolition of existing shed to clear site: $10,000
• Indicated residual to land: $720,000 − $540,000 − $10,000 = $170,000

If an alternative single-family program shows completed value $600,000 and non-land costs $450,000 (no demo needed on a vacant lot), residual = $150,000. The duplex program is more productive if it is legal and physical—here residual $170,000 beats $150,000.

If non-land costs were $700,000 against $720,000 value, residual collapses to $20,000 or the project fails feasibility entirely. High density that balloons cost can destroy residual—maximum productivity is not maximum bulk.

When Demolition Is Considered

Demolition connects as vacant thinking to a site that is currently improved:

Consider demolition / redevelopment when:

• Value of the property as improved under its current or renovated use is less than the value of the land as if vacant under HBU minus demolition and related costs (and allowing for timing/risk), or more generally when the improvements contribute nothing or negative value relative to a cleared-site program.
• The building is so functionally or physically obsolete that no feasible renovation program competes with a new ideal improvement.
• Market participants are already buying similar improved sites primarily for land value (teardown market).

Simplified decision sketch:

Let V_v = value of site as if vacant under HBU as vacant
Let C_d = demolition and make-ready cost
Let V_i = value of property as currently improved (or best improved program short of full redevelopment)

If V_v − C_d > V_i (with timing and risk considered), market logic favors treating the improvements as a teardown candidate; land residual drives the deal.

If V_i > V_v − C_d, the improvements still contribute, and HBU as improved may be to retain/renovate rather than demolish—even though HBU as vacant might still be a different long-run use.

Exam nuance: Concluding HBU as vacant is multifamily does not automatically mean the appraiser reports only land value today. If the existing building still contributes under HBU as improved, the current market value includes that contribution, possibly as an interim use until redevelopment timing improves.

Interim Use vs Long-Run Vacant Conclusion

An interim use is a temporary use that continues until the site is ripe for its long-run HBU. Examples: surface parking on a future tower site; a modest rental house on a future commercial pad; agricultural use on the urban fringe awaiting extension of sewer.

As-vacant analysis states the long-run productive use. As-improved analysis (next section) explains what to do with the building now. Both can be true at once: long-run HBU as vacant = mixed-use podium; current interim use = surface lot generating enough income to carry taxes until rents support vertical construction.

Support for Land Value and the Cost Approach

Once HBU as vacant is concluded:

• Sales comparison of vacant sites (or teardown sales) should match the same HBU—do not price multifamily land with pure single-family lot comps without adjustment or rejection.
• Extraction and allocation methods assume a use relationship between land and improved sales.
• Cost approach: Site value is added to depreciated cost of improvements; site value rests on vacant HBU. If you load multifamily land value under a building that will remain a single-family house forever under as-improved HBU, you risk inconsistent use.

Worked Scenario: Vacant Analysis on an Improved Corner

Subject: Older 1,100 sq ft cottage on a 15,000 sq ft corner zoned for neighborhood commercial and townhomes. Cottage rents for a small amount; condition is fair.

As vacant candidates after legal/physical filters: (A) new 2,200 sq ft retail shell; (B) six townhome units; (C) one large custom home (legally allowed but out of scale with commercial zoning intensity and price ceiling nearby).

Residuals (simplified):

All three are feasible (positive residual). Maximally productive / HBU as vacant = six townhomes; ideal improvement is a six-unit townhome project of market-standard quality. The cottage is likely an interim or teardown candidate depending on as-improved value versus $450,000 − remaining cottage contribution analysis.

Exam Traps for HBU as Vacant

1. Treating current improvements as proof of vacant HBU. The building may be a leftover from a prior market era.
2. Ignoring private restrictions when the zoning looks favorable.
3. Equating maximum density with maximum residual.
4. Using owner’s dream program without market support for absorption and price.
5. Forgetting entrepreneurial incentive in residual cost stacks, which overstates land residual.
6. Mixing premises: valuing land at redevelopment intensity while assuming the old building earns perpetual income without reconciliation (consistent use violation).

Bridge to As Improved

HBU as vacant tells you what the land wants to be. HBU as improved tells you what to do with the existing structure relative to that potential: keep it, fix it, change it, or remove it. The National Exam often pairs both conclusions in one vignette. Master residual logic here so the next section’s continue/renovate/convert/demolish decisions are mechanical rather than mysterious.