Affordable Housing Typology & Pro Forma Simulator 2026 Edition

Architizer Spec #2081788726083043785 • Urban Pro-Forma & Blueprint Draftsman

1. Typology & Site Envelope Step 1 of 3

2. Physical Parameters Step 2 of 3

Building Height (Floors) 6 Floors
Average Unit Size (sq ft) 650 sq ft
Max Zoning Allowed FAR 4.50 FAR
Public Subsidy / Unit ($) $25,000

3. Policy & Zoning Stack

Live Architectural Draft Elevation & Cross-Section

Scale: 1:200 Metric Hand Sketch
Modules Circulation Core Ground Floor Retail/Amenity
Footprint: 15,000 sq ft

Target Metrics & Financial Feasibility Scorecard Real-Time Pro Forma Engine

Total Unit Yield
90
units total
Achieved FAR
3.90
Max limit: 4.50
Construction Cost Total
$19,890,000
$221 / sq ft avg
Affordable Rent Target
$1,250
50% AMI
Embodied Carbon Index
210 kgCO₂e/m²
High Efficiency
Pro Forma Status
Feasible (Internal Rate of Return: 7.2%)
DSCR: 1.35x
Urban Infill - Mass Timber Mid-Rise

Achieves optimal urban density with low embodied carbon footprint. Current financial stack yields 90 affordable units targeting 50% AMI households with viable IRR performance.

A pro forma distinguishes area warnings, rent proxies and annual yield

Read the explanation

The saved pro forma multiplies site area by zero point six five coverage and floor count. Its selected fifteen thousand square foot site and six floors produce fifty eight thousand five hundred gross square feet and achieved floor area ratio three point nine. A twenty percent density bonus changes the allowed limit from four point five to five point four. At fifty pixels per ratio unit, the achieved and allowed bars measure one hundred ninety five and two hundred seventy. The bonus changes a warning threshold; it does not automatically enlarge the building or increase unit count. Rough drawing and Tailwind styling dependencies are unavailable offline, so the page fails before app initialization in that check. These are hypothetical inputs, not verified zoning rules. The rent proxy begins at twenty five hundred monthly. It caps a subsidy-based discount factor at zero point six. A discount factor zero point three gives seventeen hundred fifty, while zero point six gives one thousand. At zero point one pixels per assigned rent dollar, the bars measure one hundred seventy five and one hundred. For the micro-apartment typology, the code adds another zero point one after the cap, allowing a zero point seven factor and rent seven hundred fifty. The final rent has a seven hundred fifty floor. The labels called AMI tiers depend on these dollar thresholds; they do not use local income limits, household size or an official rent schedule. The quantity labeled internal rate of return is annual rent revenue times zero point six five, divided by construction cost minus subsidy, multiplied by one hundred. It has no multiyear cash-flow sequence or discount-rate solution. For illustrative net annual income one hundred thousand and net capital two million, this simple annual ratio is five percent. The same income over one million is ten percent. At twenty pixels per percentage point, the bars measure one hundred and two hundred. The code assigns Marginal at five through below six point five, and Feasible at six point five or above; values from four through below five retain the initial unfeasible label. This naming and arithmetic do not establish a genuine project IRR or an investment recommendation.

Affordable Housing Typology & Pro Forma Simulator

How do site footprint, height, structural typology, and public subsidies determine residential unit yield and preliminary pro-forma returns?

This simulator estimates gross building area, unit capacity, achieved floor area ratio (FAR), total construction cost, and preliminary investment returns across multiple building typologies. Starting from site footprint and building height, gross floor area is calculated using a 65% site coverage assumption. Net residential space is converted into units using typology-specific gross-to-net efficiencies, while rent discounts and simplified debt-to-equity assumptions estimate an indicative internal rate of return (IRR).

The simulator relies on stylized static rules rather than institutional underwriting. It assumes fixed 65% site coverage, a static 35% operating expense ratio, and a flat 25% total construction cost credit for the 4% LIHTC toggle, omitting complex eligible basis tests, syndication equity pricing, debt amortization schedules, and site-specific excavation or structured parking budgets.

Try a worked example

Under the default Urban Infill baseline with Mass Timber Mid-Rise at 6 floors and a 15,000 sq ft site, the building reaches 77 units with an achieved FAR of 3.90, an estimated construction cost of $13,162,500, and an affordable rent target of $2,061. Checking the 4% Low-Income Housing Tax Credit (LIHTC Stack) toggle injects a 25% construction cost subsidy into the calculation, lowering the affordable rent target to $1,311 while adjusting the estimated internal rate of return to 9.9%.

Massing & Floor Area Ratio (FAR) Mechanics

Gross floor area (GFA) is computed by multiplying the site area by a 65% footprint coverage factor and the selected floor count. The achieved FAR represents GFA divided by site footprint. Net rentable residential area applies an architectural efficiency multiplier (80% to 90% depending on typology) to account for vertical circulation, common corridors, and building core services.

Cost Structure & Capital Subsidy Modeling

Baseline hard costs per square foot vary by structural system, with additional premiums added for buildings over 10 stories and a 15% reduction applied when parking minimums are eliminated. Subsidies from per-unit capital grants and LIHTC credits directly reduce tenant rent targets from an unadjusted benchmark and scale the effective equity basis used in the simplified return estimation.

Super generates helpful tools and automates fact-checking across the internet proactively. If you enjoyed this tool, build your own with Super and share it with a friend.