Quick Start

Welcome. Here's the 60-second tour. Philly Development Intelligence is a Philadelphia-focused real estate underwriting tool — find a property, model the numbers, save the scenario, and come back to it later.

The five-step workflow

1. Find a property. Use the search bar at the top, or click any parcel directly on the map.
2. Review the parcel info. The right panel shows zoning, lot size, last sale, OPA market value, and recent permits.
3. Open the underwriter. Click Underwrite this parcel at the bottom of the parcel panel — or use the Underwriting tab in the top nav.
4. Fill in your numbers. Asking price, build cost, ARV. The badge at the bottom shows your live Return on Cost (ROC) and Profit as you type.
5. Save the scenario. Click Save Deal to keep it for later. Find it under My Deals.

Four scenarios per property

For each property you underwrite, you can save four scenarios: Base, Upside, Conservative, and Custom. The Upside and Conservative scenarios automatically adjust ARV up or down by a configurable percentage (default ±5%). Custom is for whatever you want — a different unit count, a different financing structure, an aggressive bid.

All four scenarios share the same property address but live as separate rows in My Deals, so you can compare them side by side.

Where to go next

If you're new and want to dig deeper, the Underwriting section explains every input field. The Glossary defines the acronyms. The FAQ answers the most common questions and is honest about what this tool does and doesn't do.

Map & Parcels

The map is the starting point for almost everything in this tool. Pan, zoom, and click — every parcel in Philadelphia is selectable, and you'll see zoning, ownership, sales history, and recent permits in the side panel.

Finding a property

Three ways to land on a parcel:

• Click directly on the map. Zoom in close enough that individual lots are visible, then click. Works for any parcel in the city.
• Search by address. The search bar at the top accepts full addresses (1613 Wharton St) or partials (1613 Wharton). Results come from Philadelphia's AIS service first, falling back to OpenStreetMap if that misses.
• Search by OPA number. If you already have the parcel number, just paste it in. Same search bar.

On mobile, the search bar floats at the bottom of the map. Same behavior.

Reading the parcel panel

When you click a parcel, the right-hand panel shows everything we know about it:

• Property info: OPA number, address, land use, zoning code, last sale price and date, market value (from OPA), year built, lot area, frontage, and depth. All sourced from Philly's open data.
• Zoning analysis: The zoning district, its category, permitted uses, density / FAR / height caps, and a calculated unit estimate based on the lot. Variance flags appear if zoning rules conflict with typical development.
• Overlay districts: Any overlay zones that apply (CTR — Center City Overlay, NCO — Neighborhood Conservation, /F — Floodplain, etc.) with a one-line description of what each does.
• Recent permits: The last 8 permits issued at that address, with type, status, and date.

Map layers

Six toggleable overlays in the left sidebar:

• 🗂 Zoning & Density — color-coded by zoning district, lets you see at a glance whether a block is RSA5, CMX3, IRMX, etc.
• 🚇 Transit Access — SEPTA stops and route lines. Important for transit-oriented development arguments.
• 🏫 Schools — School District of Philadelphia, charter, and private school locations.
• 💰 Price Pressure — heatmap of recent sale prices in the area. Useful for spotting trend zones.
• 🏛 Historic Districts — boundaries of properties on the Philadelphia Register of Historic Places. Historic designation affects what you can demolish and what tax credits apply.
• ▦ Overlay Districts — every overlay district in the city, individually toggleable. The Density Impact preset turns on just the ones that affect what you can build.

Data sources

All map data comes from public sources: Philadelphia's AIS (Address Information System), OPA (Office of Property Assessment), Carto-hosted city datasets for permits and zoning, and the SEPTA GTFS feed for transit. Data refreshes whenever the city pushes updates, so what you see here is as current as Philadelphia's own systems.

Underwriting (Flip Mode)

The underwriter is where you turn a property into numbers. Type in your assumptions, get back the headline metrics — Return on Cost, Profit, Margin, and an instant Strong / Marginal / Pass quality call.

This section covers Flip mode (buy-rehab-sell). For buy-rehab-rent-refi deals, see the BRRRR Mode section.

The six input cards

Inputs are grouped into six cards. Numbers update live — the bottom bar shows your current ROC, Profit, and Margin every time you type.

01 · Acquisition

• Asking Price — what the seller wants. Or your offer.
• Closing Costs — buyer-side closing. Toggle between flat dollar ($15k) or percentage (3.5%). Percentage is more accurate for deals at unusual price points.

02 · Site & Build

• Number of Units — how many units you're building (or keeping, for renovation deals).
• Lot Size (sqft) — pulled from OPA when you opened the parcel. Override if you have a survey that disagrees.
• Buildable % of Lot — how much of the lot footprint your building occupies. Set by zoning's max lot occupancy and your design.
• Stories — how many stories the structure is. Used to calculate gross building area (GBA = lot × buildable% × stories).

03 · ARV (After Repair Value)

Two ways to express what the finished project sells for:

• Total Expected ARV — single dollar figure for the whole project.
• ARV Per Unit — toggle on if you'd rather think per-unit. Multiplies by unit count automatically.

Use whichever matches how you actually price the deal. Some operators think per-unit (condos), some think total (single SFH).

04 · Hard Costs

• Construction Cost / Sqft — multiplied by GBA to get core construction cost. Defaults to $185/sf, which is reasonable for Philly mid-grade rowhouses. Adjust for high-end finishes, structural complexity, etc.
• Demolition — if there's an existing structure to remove.
• Elevators — line item because most buildings don't need them. Required for buildings over 3 stories with multiple units.
• Misc — anything else that doesn't fit a bucket (utility upgrades, etc.).

05 · Soft Costs

• Architecture / Engineering — design fees. Rough rule: 5-8% of hard costs for a custom design, less for repeat plans.
• Property Taxes During Build — paid on the empty lot or pre-improvement assessment, monthly through the build.
• City / Permit Fees — L&I permit costs, water/sewer connections, etc.
• Insurance — builder's risk insurance for the construction period.

06 · Financing

• Project Timeline (months) — how long from close to sale. Drives total interest cost.
• Borrower Equity (%) — your skin in the game. The rest is debt. 30% is typical for a hard-money construction loan.
• Interest Rate – Annual (%) — your debt cost. Hard money is usually 9-12%; private debt or relationship loans can be lower.

Interest is calculated as simple interest over the full project timeline on the debt portion only — no amortization (you don't pay down principal during construction; you pay it off at sale).

The Sale & Transaction card

• Realtor Commission — buyer + seller side, default 5%. Set to 0 if you're listing it yourself.
• Transfer Tax — Seller Share — Philadelphia's transfer tax is 4.578% total (3.578% city + 1% state), conventionally split evenly so the seller pays 2.289%. Defaults reflect this.

How the bottom-line metrics work

The bar at the bottom of the underwriter computes these in real time:

• ROC (Return on Cost) — Gross Profit ÷ Total Project Cost. The headline metric. 25%+ is Strong, 15-25% Marginal, below 15% Pass (defaults — adjust in Settings).
• Gross Profit — ARV minus all-in cost minus selling expenses.
• Margin — Gross Profit ÷ ARV. Different lens than ROC: how much of the sale price you keep.

Scenarios

Each parcel gets four scenarios you can flip between: Base, Upside, Conservative, Custom. The tabs are at the top of the underwriter.

• Base is your main assumption set.
• Upside automatically adjusts ARV up by a configurable amount (default +5%) to model a stronger market.
• Conservative adjusts ARV down by the same amount (default −5%) to stress-test.
• Custom is freeform — change anything (unit count, bid, financing) without losing your Base assumptions.

Switching tabs preserves whatever was in the previous scenario. When you save a deal, the active scenario is what gets written to My Deals. You can save all four for the same property — they live as four separate rows you can compare side by side.

BRRRR Mode

BRRRR stands for Buy, Rehab, Rent, Refinance, Repeat. Instead of selling at the end (flip), you hold the property, rent it out, and refinance to pull your capital back out for the next deal. The math is fundamentally different — you care about cash flow, cap rate, and how much equity you can recover, not gross profit on a sale.

Toggle to BRRRR mode using the 🔄 BRRRR button at the top of the underwriter (next to ⚡ Flip).

What changes vs. Flip mode

The Acquisition, Site & Build, Hard Costs, Soft Costs, and Financing cards are identical — same inputs, same purpose. BRRRR mode adds three cards (Rental Income, Operating Expenses, Refinance Loan) and replaces ARV with a different output dashboard (BRRRR Outcome).

Rental Income

• Monthly Rent / Unit — what each unit rents for monthly. Multiplied by units × 12 to get gross annual rent.
• Vacancy Rate — expected vacancy as a percentage. 5% is typical for Philly market-rate rentals. Section 8 / LIHTC properties often underwrite at 3% or lower.

Effective Gross Income (EGI) = Annual Rent × (1 − Vacancy). This is your real top-line.

Operating Expenses

Six itemized inputs, all annualized:

• Property Taxes / Year — stabilized property tax. After reassessment from the renovation, expect taxes to jump 2-5×.
• Insurance / Year — landlord insurance, not builder's risk.
• Property Mgmt — as a percentage of EGI. 8-10% is typical for third-party management.
• Repairs & Maint — also as a percentage of EGI. 5% is conservative for new construction; bump to 8-10% for older buildings.
• Capital Reserves — for big-ticket items (roof, HVAC). 5% of EGI is a reasonable rule of thumb.
• HOA / Other / Year — anything else (HOA fees, snow removal, landscaping contracts).

NOI (Net Operating Income) = EGI minus total OpEx. Critically, OpEx excludes debt service. NOI is your property's operating cash flow before any mortgage payment.

Refinance Loan

This is the back end of BRRRR — the loan you'll put on the property after stabilization.

• Appraised Value at Stabilization — the value the bank appraises after you've finished renovating and have tenants in place. Often higher than ARV-flip because rented properties appraise on income.
• Refi LTV — Loan-to-Value the bank will give you. Most lenders cap cash-out refi at 70-75% LTV for investment properties.
• Refi Interest Rate — typical conventional investor loan, currently 7-8%.
• Amortization (years) — usually 30. Some commercial loans amortize over 25 or have balloons.
• Stabilization Period (months) — time between construction completion and refi closing. Most lenders require 2-6 months of demonstrated rental income before they'll cash-out refi. Defaults to 3.

The BRRRR Outcome dashboard

Instead of ROC and Profit, BRRRR mode shows a different set of metrics — the ones that matter for hold deals:

Below the hero, four supporting metrics:

• Monthly Cash Flow — NOI divided by 12, minus monthly debt service on the refi loan. This is what hits your bank account every month after expenses and mortgage.
• Cap Rate — NOI ÷ Appraised Value. The unlevered yield. 8%+ is Strong, 6-8% Marginal, below 6% Pass.
• DSCR (Debt Service Coverage Ratio) — NOI ÷ Annual Debt Service. How much cushion you have to cover the mortgage from operations. Lenders generally require ≥1.25; under 1.0 means the property doesn't cover its own loan and you're feeding it from elsewhere.
• Year-1 Cash-on-Cash — Annual Cash Flow ÷ Cash Left in Deal. The return on your capital that's still in the deal. If Cash Left in Deal is zero (perfect BRRRR), this shows as infinity — you have any positive cash flow on zero capital.

Quality classification in BRRRR mode

In Flip mode, the quality badge uses ROC. In BRRRR mode, it uses Year-1 Cash-on-Cash. Same thresholds (Strong ≥25%, Marginal ≥15% by default) but a fundamentally different return metric.

Why CoC and not Cap Rate? Cap Rate ignores your leverage and capital recovery. CoC reflects what you're actually earning on the money you have at risk — which is the only thing that matters for portfolio compounding in a BRRRR strategy.

What makes a great BRRRR vs a mediocre one

The classic test: can you recover 100% of your capital at refi? If yes, every additional dollar of cash flow is infinite ROI because your cost basis is zero. If you leave $50k in the deal, you need that property to throw off enough cash to justify that $50k stuck there instead of in your next acquisition.

The two levers that drive perfect-BRRRR outcomes:

• Buy at enough of a discount that ARV − Project Cost is meaningful equity. Most BRRRRs that fail to recover capital simply paid too much going in.
• Find a market where appraised-value-at-stabilization exceeds project cost after a renovation. This is the heart of "forced appreciation" — you create value through the rehab that the appraiser recognizes.

My Deals

Every scenario you save lands in My Deals. It's both an archive and a working list — sort, filter, search, and click into any deal to reload it in the underwriter.

How deals are organized

Deals are grouped by property address. If you've saved Base, Upside, and Conservative scenarios for the same address, they appear as one tile on the main grid — click in to see all three scenarios side by side.

The main grid shows one tile per unique address with the best performing scenario's metric on top. Click any tile to drill into the scenario detail view.

Quality badges

Every saved deal gets a quality badge based on its primary return metric:

• Strong — meets or beats your "Strong" threshold (default 25% ROC) for flips, 25% Year-1 CoC for BRRRR
• Marginal — between Strong and Pass thresholds (15-25% by default)
• Pass — below the Marginal threshold

Thresholds are set per-user in Settings and are stored on each deal at save time. If you change your thresholds later, already-saved deals retain the thresholds they were saved with — so a deal you flagged as Strong last year doesn't quietly become Marginal because you raised your bar.

Filter & sort controls

• Search — free-text search across address, zoning, and deal name.
• Zone filter — narrow to deals in a specific zoning district. Useful if you've underwritten a lot of properties and want to see all your CMX-3 plays.
• Quality filter — Strong / Marginal / Pass only. Helpful when you want to see only deals worth a follow-up.
• Deal type filter — All / Flip only / BRRRR only.
• Sort by — most recent, best return, lowest ask, alphabetical. Default is most recently updated.

Editing a deal

Click any scenario card in the detail view → the underwriter opens with that scenario's exact inputs loaded. Make changes, hit Save Deal — you'll be asked whether to overwrite the existing row or save as a new copy.

Use Save as new copy when you want to keep the original snapshot intact (e.g. before a price reduction makes you re-underwrite).

Deleting

The 🗑 icon on each scenario card deletes that single scenario. You're asked to confirm. Deletion is permanent — there's no trash or undo. If you want to keep the data but remove it from your active list, save it under a different scenario name or address and clean up the duplicates.

Settings

Settings is where you teach the underwriter your defaults. Every new deal will start with these values pre-filled instead of generic ones. Two minutes here saves you typing the same numbers a hundred times.

01 — Profile & Contact

Your name, email, company, role, phone. Used for display only — your email is read-only because it's tied to your Google sign-in.

02 — Deal Quality Thresholds

Your personal Strong / Marginal / Pass cutoffs. Defaults are 25% Strong and 15% Marginal. Lower the bar if you're hunting in tight markets; raise it if you're being picky.

These thresholds apply to both Flip (ROC) and BRRRR (Year-1 CoC) modes. They're saved with each deal at save time, so changing them later doesn't reclassify your old deals.

03 — Acquisition Defaults

How closing costs get computed by default. Two modes:

• Percentage — e.g. 3.5% of asking price. Scales naturally with deal size.
• Flat dollar — e.g. $15k. Useful if your closing costs are largely fixed (title insurance, legal, etc.).

04 — Construction Cost Defaults

• Hard Cost / Sqft — your typical $/sf for new construction. Defaults to $185. Adjust for your finish level and trade pricing.
• Soft Cost % of Hard — architecture, engineering, permits as a percentage of hard costs. Default 12%.
• Contingency % — buffer for cost overruns. Default 8%. Higher for older buildings or unknown soil conditions.

05 — Financing Defaults

• Project Timeline — your typical build duration in months.
• Borrower Equity % — your typical equity contribution.
• Interest Rate — your typical debt cost. Set this to your actual hard-money or private debt rate.

06 — Sale Defaults

• Realtor Commission % — total commission paid at sale (buyer + seller side combined). Default 5%.
• Transfer Tax — Seller Share — Philadelphia's transfer tax is 4.578% total, conventionally split, so seller pays 2.289%. Adjust if you negotiate a different split.

07 — Scenario Adjustments

The ARV swings used when you click Upside or Conservative scenarios in the underwriter.

• Upside · ARV increase — default +5%. Models a stronger sale market.
• Conservative · ARV decrease — default −5%. Stress-tests your downside.

Some operators use larger swings (±10% or ±15%) to model bigger market movements. Choose what reflects your actual market uncertainty.

Glossary

All the acronyms used in the underwriter, in alphabetical order. If you've seen something here and weren't sure what it meant, this is your reference.

ARV — After Repair Value

What the property is worth (or sells for) after your renovation is complete. The "exit value" for a flip; the "appraised value" for a BRRRR. Comparable sales are the most defensible way to estimate it.

Cap Rate — Capitalization Rate

NOI ÷ Property Value, expressed as a percentage. The unlevered yield — what the property returns if you bought it cash. A higher cap rate means more income per dollar of value (and usually more risk or less desirable location).

Cash Left in Deal

For BRRRR deals. The portion of your capital you couldn't recover at refinance. Calculated as Total Project Cost − Refi Loan Amount. Zero or negative means you got all your money back ("perfect BRRRR"). Positive means that much is still tied up.

CoC — Cash-on-Cash Return

Annual Cash Flow ÷ Cash Invested. The yield on the actual capital you have at risk. In the underwriter, "Year-1 CoC" means Year 1's cash flow divided by Cash Left in Deal after refi.

DSCR — Debt Service Coverage Ratio

NOI ÷ Annual Debt Service. How much NOI you have relative to your mortgage payments. Lenders typically require ≥1.25 for investment property loans. Under 1.0 means the property doesn't cover its own loan.

EGI — Effective Gross Income

Gross Rental Income × (1 − Vacancy Rate). The actual collected rent you expect after accounting for empty units. Don't use gross rent — vacancy is real and lenders will haircut your numbers if you ignore it.

FAR — Floor Area Ratio

A zoning constraint. The ratio of total building floor area to lot area. FAR 2.0 on a 1,000 sf lot allows 2,000 sf of building (across all floors). Sets the cap on how much you can build before height/density rules kick in.

GBA — Gross Building Area

Total square footage of your finished building, measured to outside walls, all floors. Used to calculate hard cost (GBA × $/sqft). Different from "net rentable" which excludes hallways, mechanical rooms, etc.

LTV — Loan-to-Value

Loan Amount ÷ Property Value. The percentage of the property's value the bank will finance. Cash-out refi on an investment property is typically capped at 70-75% LTV.

Margin — Profit Margin

Gross Profit ÷ ARV, as a percentage. Different lens than ROC: how much of the sale price you keep as profit. A complement to ROC, not a replacement.

NOI — Net Operating Income

EGI minus all operating expenses. Critically, NOI excludes debt service — it's the property's cash flow before any mortgage. Cap rates, DSCR, and property valuations are all based on NOI.

OpEx — Operating Expenses

All recurring costs to operate the property: taxes, insurance, management, maintenance, reserves, HOA fees. Excludes debt service and capital improvements.

OPA — Office of Property Assessment

Philadelphia's assessor. The OPA number is the unique ID for every parcel in the city. OPA market value is the city's assessed value (for tax purposes); rarely matches actual market price.

ROC — Return on Cost

Gross Profit ÷ Total Project Cost, as a percentage. The headline metric for flip deals. Different from ROI because the denominator is total cost (acq + build + soft + financing), not just your equity.

TPC — Total Project Cost

Everything you spend on the deal from acquisition through completion: purchase price + closing costs + hard costs + soft costs + financing costs. The "all-in" number.

FAQ & Limits

Common questions, troubleshooting, and a candid list of what this tool does and doesn't do. Read this section if you're going to rely on the underwriter for real money decisions.

What this tool is

A fast scratch pad for evaluating Philly real estate deals. The numbers are math, not magic — same formulas a seasoned developer would use on a spreadsheet, but with the address lookup, zoning data, and comp permits already filled in.

What this tool is not

• Not legal advice. The zoning analysis is a reference based on the Title 14 Philadelphia Zoning Code. Variances, overlays, historic designations, and conditional uses all add complexity that no automated tool fully captures. Always confirm with the city or your zoning attorney before committing.
• Not an appraisal. ARV is what you tell it. Pull real comps from the MLS or Zillow before trusting any number you've typed in.
• Not a substitute for due diligence. Permits shown are public record but may be incomplete. OPA market value is for tax assessment, not market price. Title issues, environmental concerns, structural issues — none of these are surfaced here.
• Not a financial advisor. Profit projections are scenario-based math, not guarantees. Real deals come in over or under budget all the time.

Common questions

Why is my saved deal classified differently than it was in the underwriter?

It shouldn't be — but if you see this, the most common cause is that you saved the deal before completing all inputs (e.g. ARV at $0), then opened it and the badge updated to reflect the now-valid values. Loading a saved deal restores its inputs but recomputes the badge on the fly.

Why does the zoning analysis flag my address as "variance required" when L&I tells me it's by-right?

Zoning is unfortunately nuanced. The tool flags potential variances based on common scenarios (small lot sizes, density above base allowances, etc.) but it doesn't know about every special exception, overlay-specific carve-out, or zoning bulletin. Treat variance flags as worth investigating, not as facts.

My ARV per unit looks low — what comps does the tool use?

The tool doesn't pull comps automatically. The ARV field is whatever you type. Pull recent comparable sales from your MLS or from the Price Pressure map layer to inform your ARV input.

My transfer tax estimate doesn't match what I paid on my last deal.

Philadelphia's transfer tax changed mid-2025 to a total of 4.578% (3.578% city + 1% state), conventionally split with seller paying half (2.289%). If your deal was earlier, the rate was different. Commercial transfers and some entity-to-entity transfers also have different rules. Adjust the field if your specifics differ.

How accurate is the hard-cost default?

The $185/sf default reflects mid-range Philadelphia rowhouse construction in 2025-2026. It's a starting point. Real numbers vary widely:

• $130-160 — very basic build, repeat plans, suburban-quality finishes
• $165-200 — typical Philly market-rate rowhouse
• $210-280 — high-end finishes, complex site, mass timber, or condo-quality build
• $300+ — luxury, historic restoration, or extreme structural conditions

Set your typical $/sf in Settings so the underwriter starts from your reality.

Why doesn't the BRRRR Outcome show a Year-1 CoC number?

If Cash Left in Deal is zero or negative (perfect BRRRR — you got all your capital back at refi), Year-1 CoC is mathematically infinite. The dashboard shows "—" or "∞" in that case. The headline metric to look at is Monthly Cash Flow when this happens — any positive cash flow is essentially infinite return on zero capital.

Are my saved deals private?

Yes. Each user can only see their own saved deals. Admin users (Rarity team) can see all users' deals for support and aggregate analytics, but no other user can see yours. This is enforced at the database level, not just in the UI.

Can I export my deals?

Not yet — but on the roadmap. For now, if you need an export, contact the team and we can pull a CSV for you.

Troubleshooting

"Could not load deals — connection issue"

Hit retry first — usually a transient network blip. If it persists, sign out and back in (sometimes your session token has expired beyond what auto-refresh can recover). If that doesn't work, refresh the page.

"Save failed"

Most common cause: session expired. Sign out, sign back in, retry the save. If you see this repeatedly, screenshot the error and send it to the team.

Search returns no results for a valid Philly address

The address lookup uses Philly's AIS service first, which is excellent but occasionally misses very new constructions or unusual addresses. The tool falls back to OpenStreetMap automatically. If both miss, click the parcel directly on the map at the right location — that bypasses the address service entirely.

The map is slow or unresponsive

Heavy overlay layers (Overlay Districts especially) load thousands of geometries. Toggle them off when not needed. On older phones or slow connections, expect a few seconds of load time when you first open a layer.