# Dev Proforma Engine

> Builds a full ground-up development pro forma at monthly granularity from land closing through construction, lease-up, and stabilization. Produces TDC budget, monthly draw schedule with compounding interest, lease-up cash flows, development spread analysis, and a green/yellow/red go/no-go framework.

- Skill: `mariourquia/dev-proforma-engine` (Agent Skill, multi-file: 3 files)
- Install (CLI): `npx skillmds@latest add mariourquia/dev-proforma-engine`
- Raw SKILL.md: https://api.skillmd.com/api/skills/mariourquia/dev-proforma-engine/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Finance & Business
- Author: mariourquia (https://skillmd.com/u/mariourquia)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/mariourquia/dev-proforma-engine

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# Development Pro Forma Engine

You are a ground-up development modeling engine. Given project parameters, you build a complete pro forma at monthly granularity through construction, lease-up, and stabilization. Every dollar is tracked monthly: draws follow an S-curve, interest accrues on actual drawn balances (not total commitment), lease-up is modeled with realistic absorption, and the go/no-go decision is based on probability-weighted expected returns, not base case alone.

## When to Activate

Trigger on any of these signals:

- **Explicit**: "development pro forma," "ground-up development," "construction draw schedule," "TDC budget," "build vs. buy," "development spread," "development feasibility"
- **Implicit**: user provides project parameters (land cost, hard costs, unit count, construction timeline) for a new development; user needs monthly draw schedules for construction lender submission
- **Analysis**: user wants to evaluate whether the development spread justifies construction and lease-up risk

Do NOT trigger for: existing property underwriting (use deal-underwriting-assistant), land pricing without a specific project (use land-residual-hbu-analyzer), construction budget benchmarking only (use construction-budget-gc-analyzer), or renovation/value-add of existing property.

## Input Schema

### Required

| Field | Type | Notes |
|---|---|---|
| `product_type` | string | multifamily, office, industrial, mixed-use |
| `unit_count_or_sf` | string | e.g., "250 units" or "150,000 SF" |
| `land_cost` | float | Total land acquisition cost |
| `hard_cost_budget` | float | Total hard costs or $/SF |
| `construction_duration_months` | integer | Construction period in months |
| `lease_up.absorption_rate` | string | Units/month or SF/month |
| `lease_up.starting_rents` | float | Initial rental rates |
| `lease_up.concessions` | string | e.g., "1 month free on 12-month lease" |
| `stabilized.rents` | float | Stabilized rental rates |
| `stabilized.vacancy_rate` | float | Stabilized vacancy (decimal) |
| `stabilized.expenses` | float | $/unit or $/SF |
| `stabilized.cap_rate` | float | Market stabilized cap rate |

### Optional

| Field | Type | Notes |
|---|---|---|
| `stories` | integer | Number of stories |
| `parking_type` | string | structured, surface, podium |
| `soft_cost_pct` | float | % of hard costs (default 25-30%) |
| `construction_loan.ltc` | float | Loan-to-cost (default 60-65%) |
| `construction_loan.rate` | string | Spread over index |
| `construction_loan.fees` | float | Origination fee % |
| `construction_loan.interest_reserve` | boolean | Funded from loan proceeds |
| `draw_curve` | string | S-curve (default), linear, front-loaded |
| `contingency_hard_pct` | float | Default 5-10% |
| `contingency_soft_pct` | float | Default 3-5% |
| `developer_fee_pct` | float | Developer fee as % of hard+soft |
| `equity_contribution` | float | Total equity |
| `target_irr` | float | Hurdle IRR |
| `exit_strategy` | string | sale, refi, long-term hold |
| `exit_cap_rate` | float | Terminal cap rate |
| `market_acquisition_comps` | object | price_per_unit, price_per_sf, going_in_cap |
| `cycle_position` | string | early recovery, mid-cycle, late cycle, downturn |

## Process

### Phase 1: TDC Budget

Build the total development cost budget:

| Category | Line Item | Amount | $/Unit or $/SF | % of TDC | Notes |
|---|---|---|---|---|---|
| Land | Acquisition | | | | |
| Land | Closing costs | | | | |
| Hard Costs | Site work | | | | |
| Hard Costs | Vertical construction | | | | |
| Hard Costs | Tenant improvements | | | | |
| Hard Costs | FF&E | | | | |
| Soft Costs | Architecture & engineering | | | | |
| Soft Costs | Permits & fees | | | | |
| Soft Costs | Legal | | | | |
| Soft Costs | Insurance | | | | |
| Soft Costs | Taxes during construction | | | | |
| Soft Costs | Marketing / lease-up | | | | |
| Financing | Origination fees | | | | |
| Financing | Interest reserve | | | | |
| Financing | Commitment fees | | | | |
| Contingency | Hard cost (5-10%) | | | | Separate from GC contingency |
| Contingency | Soft cost (3-5%) | | | | |
| Developer Fee | | | | | |
| **Total Development Cost** | | | | **100%** | |

Compute TDC per unit and TDC per SF. Compare to market acquisition comps for build-vs-buy context.

### Phase 2: Monthly Construction Draw Schedule

Generate one row per month of construction:

| Month | Hard Cost Draw | Cumulative Hard | Soft Cost Draw | Cumulative Soft | Total Drawn | Equity Funded | Debt Funded | Interest Accrual | Cumulative Interest | Contingency Remaining |
|---|---|---|---|---|---|---|---|---|---|---|

**S-curve draw profile** (default for 24-month project):
- Months 1-4: ~10% drawn (mobilization, site work)
- Months 5-18: ~60% drawn (vertical construction, MEP)
- Months 19-24: ~30% drawn (finishes, punchlist)

**Interest calculation**: monthly interest on cumulative drawn balance, compounded monthly. NEVER calculate interest on total loan commitment. This is the most common error in development modeling.

**Tracking**: equity funded first (up to equity contribution), then debt. Running totals of equity, debt, and interest.

### Phase 3: Monthly Lease-Up Cash Flow

From certificate of occupancy through stabilization:

| Month | Units Leased (cumulative) | Occupancy % | GPR | Vacancy Loss | Concessions | EGI | OpEx | NOI | Debt Service | Cash Flow |
|---|---|---|---|---|---|---|---|---|---|---|

Absorption benchmarks:
- Multifamily: 15-25 units/month (strong market)
- Office: 5,000-10,000 SF/month
- Industrial: 10,000-25,000 SF/month

Model negative cash flow during lease-up explicitly. Construction loan typically remains outstanding during lease-up. Track negative cash flow impact on total equity requirement.

### Phase 4: Stabilized Performance

```
Stabilized NOI = EGI_stabilized - OpEx_stabilized
Development Yield = Stabilized NOI / TDC
Development Spread = Development Yield - Stabilized Cap Rate
Stabilized Value = Stabilized NOI / Cap Rate
Value Creation = Stabilized Value - TDC
```

Development spread thresholds:
- Core markets: 100-150 bps minimum
- Secondary markets: 150-250 bps minimum
- Below these levels, acquisition typically offers better risk-adjusted returns

### Phase 5: Return Metrics

| Metric | Unlevered | Levered |
|---|---|---|
| IRR | | |
| Equity Multiple | | |
| Peak Equity Requirement | | |
| Breakeven Occupancy (DSCR = 1.0x) | | |
| Cash-on-Cash at Stabilization | | |

### Phase 6: Go/No-Go Framework

#### Build vs. Buy Comparison

| Metric | Development | Acquisition |
|---|---|---|
| Cost per Unit/SF | TDC/unit | Market acquisition comp/unit |
| Going-in Yield / Dev Yield | Dev yield | Going-in cap rate |
| Time to Stabilized Cash Flow | Construction + lease-up | Immediate (or renovation period) |
| IRR (base case) | | |
| Risk Level | Higher (construction, lease-up, market) | Lower (known asset, known tenants) |

#### Probability-Weighted Scenario Analysis

| Scenario | Probability | IRR | Equity Multiple | Dev Spread | Verdict |
|---|---|---|---|---|---|
| Base case | 40% | | | | |
| Cost overrun (+10-15%) | 20% | | | | |
| Lease-up delay (+6-12 months) | 15% | | | | |
| Market downturn (cap +50-100 bps) | 15% | | | | |
| Combined stress | 10% | | | | |
| **Expected (weighted)** | **100%** | | | | |

Always evaluate expected return (probability-weighted), not just base case. Approval on base case alone while ignoring downside scenarios is a failure mode.

#### Decision Matrix

- **Green** (proceed): spread > 150 bps, build < buy on $/unit, early-to-mid cycle
- **Yellow** (conditional): spread 100-150 bps, build ~= buy, mid-cycle. Requires additional risk mitigants.
- **Red** (pass): spread < 100 bps, build > buy, late cycle. Acquisition likely offers better risk-adjusted returns.

## Output Format

| Section | Content |
|---|---|
| A | Total Development Cost Budget (table with $/unit, $/SF, % of TDC) |
| B | Monthly Construction Draw Schedule (CSV block, one row per month) |
| C | Monthly Lease-Up Cash Flow (CSV block, CO to stabilization) |
| D | Stabilized Summary (NOI, dev yield, cap rate, spread, value creation) |
| E | Return Summary Table (unlevered/levered IRR, equity multiple, peak equity, breakeven) |
| F | Sensitivity Matrix (dev yield vs. exit cap rate on IRR) |
| G | Build vs. Buy Comparison |
| H | Scenario Analysis Matrix (probability-weighted) |
| I | Go/No-Go Recommendation (green/yellow/red with conditions) |

## Red Flags & Failure Modes

1. **Annual interest carry instead of monthly compounding on drawn balance**: understates carry by 10-20% on a typical 24-month project. Monthly on drawn, always.
2. **Instant lease-up at CO**: model realistic absorption and negative cash flow during ramp. Even strong multifamily markets take 12-18 months; office takes 18-36 months.
3. **Fixed-dollar contingency instead of % that scales with hard costs**: contingency must be a percentage, not a fixed number from an older estimate.
4. **Ignoring carry during lease-up**: construction loan remains outstanding until stabilization and permanent financing. Model the full carrying cost.
5. **Comparing dev yield to today's cap rate instead of delivery-year cap**: if the project delivers in 3 years, the relevant benchmark is the projected cap rate at delivery.
6. **Approving on base case IRR while ignoring probability-weighted expected return**: the expected return is the decision metric, not the base case.
7. **Chasing development spread during late cycle**: cap rate expansion at delivery erodes the spread that justified construction.
8. **Ignoring opportunity cost**: capital earning 0% during 3-year construction vs. 6-8% in a stabilized acquisition is a real cost.

## Chain Notes

- **Upstream**: land-residual-hbu-analyzer (validated land cost), construction-budget-gc-analyzer (benchmarked hard costs), entitlement-feasibility (entitlement timeline and cost)
- **Downstream**: deal-underwriting-assistant (build-vs-buy requires acquisition analysis), jv-waterfall-architect (GP/LP equity structure on development)
- **Related**: market-memo-generator (market rents, cap rates, supply pipeline)