Corner-Lot Duplex: Highest and Best Use with a Tree Ordinance and a Nonconforming Structure
You are appraising a 20,000-square-foot corner lot improved with a 1925 duplex. Zoning is R-3, which permits 12 units per acre; the duplex is a legal nonconforming use because the rear setback is 18 feet where 25 feet is now required. Under the zoning ordinance, a nonconforming structure damaged more than 50% of its replacement cost cannot be rebuilt as of right. A 60-inch-diameter oak in the rear yard is protected; removing it requires a permit and an $18,000 mitigation payment. Demolition of the duplex would cost $25,000. The duplex generates $2,500 per month total; market rent for a new four-unit building would be $1,650 per unit per month, with 5% vacancy and a 6.5% capitalization rate. New four-unit construction, including site work, would cost $780,000. Entrepreneurial profit in this market is 10% of total cost. Comparable vacant lots sell for $7.00 per square foot. The owner wants the appraisal 'as is' and asks whether the highest and best use is to tear down the duplex.
1. Apply the four highest and best use tests as though vacant and as improved. What is your preliminary conclusion?
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As though vacant: Legally permissible - R-3 permits 12 units per acre; 20,000 sq ft is 0.459 acre, so about 5.5 units, meaning a four-unit building is allowed. The tree ordinance does not prohibit development, but removal requires a permit and mitigation. Physically possible - the lot is a corner parcel and a four-unit building can be designed around the tree, or the tree can be removed with approval. Financially feasible - the residual test below shows a positive result. Maximally productive - a four-unit building is likely the highest-value legal use. As improved: The duplex is a legal nonconforming structure. It passes the legal test because existing nonconforming use may continue, but expansion or rebuilding after major damage is restricted. It is physically possible and financially feasible. However, the existing duplex is not maximally productive if redevelopment produces a higher residual value. The as-improved HBU is therefore either continued duplex use as an interim use or redevelopment, depending on entitlement and market risk. My preliminary conclusion is that the as-vacant HBU is a four-unit residential building; the as-improved HBU is redevelopment, with the duplex contributing interim income.
2. Test the financial feasibility of redevelopment. Show the calculations and explain how entrepreneurial profit, tree mitigation, and nonconforming status affect the conclusion.
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Stabilized NOI for four units = 4 × $1,650 × 12 = $79,200 gross; at 5% vacancy, $75,240. Direct capitalization at 6.5% gives $75,240 / 0.065 = $1,157,538. Total cost = $780,000 construction + $25,000 demolition + $18,000 tree mitigation = $823,000. Entrepreneurial profit at 10% of cost = $82,300, so total cost including profit = $905,300. Residual = $1,157,538 − $905,300 = $252,238, positive. That indicates redevelopment is financially feasible. The tree mitigation is a real cost and must be included; the nonconforming status matters because the existing duplex can continue but cannot be expanded as of right, and a new building must meet current setbacks. The permit for tree removal is an entitlement risk, not a certainty. If the permit were denied and the design could not accommodate the tree, the site yield could fall, so the conclusion should be conditioned on feasibility of the permit or tested with a lower unit count. I would also test a higher vacancy rate and a lower rent to see how robust the residual is.
3. How should the highest and best use conclusion be reflected in the as-is value and the report?
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The HBU conclusion must drive the value. If the as-improved HBU is redevelopment, the as-is market value should reflect the property's redevelopment potential, not just capitalize the duplex's current income as if it were the permanent use. The value should reconcile the income value of the existing duplex, the land value less demolition and mitigation, and the redevelopment residual, with appropriate discounts for entitlement risk, construction cost, and lease-up. The report should state the HBU as vacant and as improved, disclose the legal nonconforming status and tree permit requirement, and explain that the duplex may be an interim use. I would not simply select the highest calculated number; I would weigh market evidence of what buyers actually pay for redevelopment sites and improved nonconforming properties. The appraisal should also state that the conclusion is subject to the necessary permits and approvals if the value relies on redevelopment.