Method
How these numbers are built.
Every report runs on a pro forma model with a stated approach, a full list of inputs, and a sensitivity test against its own conclusion. None of that belongs in the middle of an argument, so it lives here instead.
R-01 · Washington, D.C.
The technical backing for the Washington, D.C. report: does the conclusion hold up under different assumptions, where every input comes from, and exactly how the model works.
Does this hold up?
A model that only produces one answer is not a model. Each material input moved to the ends of its defensible range, one at a time:
| Assumption | Low | Base | High |
|---|---|---|---|
| Hard cost, $/SF | 4.38% (at $220) | 3.72% | 2.95% (at $370) |
| Achievable rent | 2.98% (at $2,113) | 3.72% | 4.70% (at $2,900) |
| Land | 4.00% (at $1.5M) | 3.72% | 3.42% (at $3.5M) |
| Operating expenses per unit | 4.14% (at $7,500) | 3.72% | 3.40% (at $11,000) |
| Construction loan rate | 3.76% (at 6.5%) | 3.72% | 3.67% (at 9.5%) |
| Exit cap rate | 3.66% (at 4.75%) | 3.72% | 3.78% (at 6.00%) |
| Soft cost % | 3.88% (at 15%) | 3.72% | 3.57% (at 25%) |
| Vacancy | 3.84% (at 5.0%) | 3.72% | 3.59% (at 9.0%) |
No single input, moved to its most favorable defensible end, clears 6.50 percent. The two that move the answer most, hard cost per square foot and achievable rent, are both cost-structural. Neither is a zoning variable.
To confirm the model is not rigged to fail: set every input to its most favorable end simultaneously and apply the full reform package. Return on cost is 8.45 percent, comfortably clearing. The model can produce a feasible building. Washington's current conditions cannot.
What would actually close it
At the regulatory ceiling, holding everything else at base: rent would need to reach $3,240 a month, a 32 percent increase, in a market where rents fell 3.8 percent last year.
Residual land value is negative $1.5 million. A merchant builder cannot pay for the dirt. They would need to be paid to take it.
That second number is the whole report in one line. At the current cost of construction and the current level of rents, a well-located D.C. site zoned for forty apartments is a liability rather than an asset to anyone whose business is building apartments.
Input manifest
Status flags: VERIFIED: published figure from a named source. VERIFIED_RANGE: base case sits inside a published range. DERIVED: computed from verified inputs. ESTIMATE: professional judgment, the priority validation queue.
| # | Input | Value | Status | Source |
|---|---|---|---|---|
| 1 | Units | 40 | ASSUMPTION | Model design |
| 2 | Unit mix and sizes | 484 / 697 / 996 SF | VERIFIED | RentCafe / Yardi Matrix, Aug 2026 |
| 3 | Efficiency ratio | 80% | ESTIMATE | Reflects two-stair mandate |
| 4 | Land cost | $2,400,000 | ESTIMATE | ~$205/land SF at FAR 3.0; 26% below D.C. asking average of $278/SF |
| 5 | Hard cost, shell and core | $275/GSF | VERIFIED_RANGE | RLB QCR Q1 2026, D.C. multifamily $220–370/SF |
| 6 | Structured parking cost | $35,000/space | VERIFIED | D.C. Policy Center, below-grade |
| 7 | Parking ratio | 0.50/unit | ESTIMATE | Minimums bind on 96% of D.C. residential lots |
| 8 | Soft costs | 20% of land + hard | ESTIMATE | Priority validation |
| 9 | Entitlement timeline | 14 months | ESTIMATE | Priority validation |
| 10 | Construction timeline | 18 months | ESTIMATE | Priority validation |
| 11 | Construction loan rate | 8.00% | VERIFIED_RANGE | SOFR ~4.8% + 275–400 bps; multifamily construction average 7.6% |
| 12 | Achievable rent | $2,450/mo | VERIFIED | RentCafe / Yardi Matrix, citywide average $2,446 |
| 13 | Inclusionary zoning set-aside | 10% of units | VERIFIED | D.C. Policy Center, program requires 8–12.5% of residential floor area |
| 14 | IZ rent, 60% MFI | $1,550/mo | ESTIMATE | Refine against DHCD 2026 IZ schedule |
| 15 | Vacancy and credit loss | 7.0% | DERIVED | Yardi Matrix occupancy 94.2%; Northmarq vacancy 5.2% |
| 16 | Other income | 3% of GPR | ESTIMATE | Industry convention |
| 17 | Operating expenses | $9,500/unit/yr | ESTIMATE | Priority validation |
| 18 | Property tax rate | 0.85% | VERIFIED | D.C. OTR, Class 1A, $0.85 per $100 |
| 19 | Exit cap rate | 5.25% | VERIFIED_RANGE | CBRE H1 2026, D.C. Class A stabilized infill 4.75–5.5% |
| 20 | Required developer spread | 125 bps | ESTIMATE | Standard merchant-build screen |
Priority validation queue: soft cost percentage (#8), entitlement timeline (#9), construction timeline (#10), operating expenses (#17). Land (#4) is now triangulated against published asking prices and one transaction, and the conclusion is independent of it.
Full source list
Permits and production
- U.S. Census Bureau, Building Permits Survey: New Private Housing Units Authorized, D.C. (DCBPPRIV) via FRED
- U.S. Census Bureau: Resident Population in the District of Columbia (DCDIST5POP) via FRED
- D.C. Office of Planning: 2025 Census population estimates
- D.C. Policy Center: D.C. population growth slowed in 2025
- Bisnow: D.C. construction starts at a 15-year low
- Housing&: Housing Indicator Tool 6.0, Capital Region
Policy and regulation
- D.C. Policy Center: Breaking the scarcity-subsidy cycle (primary source)
- D.C. Policy Center: Reducing regulatory barriers to housing production
- D.C. Policy Center: Reforming Inclusionary Zoning
- D.C. Office of Zoning: Planned Unit Developments
- D.C. Department of Buildings: Plan Review and Permit Timelines (SLAs)
- Mayor's Office: 36,000 homes by 2025 milestone
- D.C. Office of Planning: Housing Framework for Equity and Growth
- D.C. Office of Tax and Revenue: Real Property Tax Rates
- D.C. Fiscal Policy Institute: Where D.C. gets its money, residential property tax
Costs, rents, capital markets, land
- Rider Levett Bucknall: Quarterly Construction Cost Report Q1 2026 (PDF)
- Rider Levett Bucknall: East region commentary Q1 2026
- RentCafe / Yardi Matrix: Average rent in Washington, D.C.
- Yardi Matrix: Washington D.C. multifamily market report
- Northmarq: Washington D.C. multifamily market overview
- Marcus & Millichap: D.C. 2026 multifamily investment forecast
- CBRE: U.S. Cap Rate Survey H1 2026
- Bisnow: Vacant sites flooding the market as D.C. construction stalls
- Bisnow: JBG Smith sells site of long-stalled NoMa development for $11M
- LoopNet: D.C. land parcels for sale
Limitations
The model is a merchant-build screen. A long-hold owner, a mission-driven developer with patient capital, or a project stacking low-income housing tax credits faces different arithmetic. The 6.50 percent hurdle is the right test for the marginal private dollar, not for every dollar.
Site-specific costs (remediation, historic façade retention, protected trees, public-space exactions) are excluded. Each is real in Washington and each pushes the answer further negative. The model is optimistic, not pessimistic.
Four inputs remain professional estimates rather than published figures. They are flagged in the manifest and will be updated against primary records.
The 2026 permit uptick is unresolved. If the second half of 2026 sustains the May–June pace, part of this analysis will need revisiting. I will publish an update when the full year is available rather than quietly leave the earlier framing in place.
Approach
The model asks one question. Build the building, rent it, run it for a year, and what does it earn as a share of what it cost?
That is the return on cost. It gets compared to what an investor needs: the rate a finished building of this type trades at, plus 1.25 percentage points to compensate for the risk of building it. In Washington that comes to 6.50 percent.
This is a single-year snapshot, not a full cash flow projection. It is the screen a developer runs before a deal gets a second meeting, and it is the right test for whether something gets built.
Three details are easy to get wrong, so they are stated plainly:
- Construction interest is charged on half the loan. A construction loan pays out in stages as work progresses, so the average balance over the build is roughly half the total. Charging interest on the full amount for the full term overstates the cost by about double.
- Entitlement interest is charged on the full land price. Land is bought in one go, so the whole balance accrues interest from day one.
- Vacancy is deducted. No building is 100 percent leased and paying. Models that skip this step overstate income and therefore overstate value.
Property tax is solved by iteration. The tax depends on the assessed value, the assessed value depends on the income, and the income depends on the tax. The model loops until the three agree.
Calculator sources, all cities
The pro forma calculator runs the same
R-01 engine across Washington, D.C., Los Angeles, Detroit, San
Francisco, New York City and Miami, plus a frictionless benchmark.
Land, hard cost, rents, timelines, taxes and exit caps are set per
city in src/data/city-proforma.json; unit mix,
efficiency, and construction financing are held constant across
cities so only local conditions vary. Sources not already listed
above, for the other five cities:
- Rider Levett Bucknall, Quarterly Construction Cost Report Q1 2026 (PDF): multifamily $/SF for D.C., Los Angeles, San Francisco, New York, Miami
- RentCafe / Yardi Matrix city rent pages: D.C., Los Angeles, New York, Detroit, Miami, San Francisco
- Yardi Matrix, Multifamily Metro Reports archive: occupancy and rent trend by metro
- REJournals, Detroit multifamily momentum, early 2026: Detroit rent and occupancy via Yardi
- The Real Deal, LABCI study on L.A. approval and construction timelines: 549 days entitlement, 863 days construction
- SPUR / O'Neill, Berkeley Law Getting It Right data (PDF): median entitlement months by California jurisdiction
- UCLA ITS, Does Discretion Delay Development?: by-right projects permitted 28% faster in L.A.
- CRE Daily, CBRE H1 2026 Cap Rate Survey summary: NYC stabilized multifamily 5% to 5.5%; infill multifamily most bearish
- CRE Daily, LoopNet 2026 multifamily city rankings: Detroit 11.42% average cap rate
- Lev, Multifamily cap rates 2026: Class A primary market 4.5% to 5.5%
- ManageCasa, Florida rental market 2026: Miami vacancy, Florida insurance costs
Land is an estimate in every city but D.C., where it was
triangulated against asking prices and one transaction. Detroit
hard cost is a proxy; RLB does not cover the market. Property tax
rates for the four non-D.C. cities are effective-rate
approximations, not published statutory figures, because those
cities' effective rates depend on assessment practice. Entitlement
timelines for Detroit, Miami and New York are professional
estimates. Each of these is flagged ESTIMATE in
city-proforma.json and on the calculator page.