Gray Kuglen

PropDev: turning one house into six homes

Personal project · 2026 · Design · Build · Financial modeling

A financial model and working calculator for replacing aging single-family homes with 6–10 smaller units, priced for buyers who can’t afford the house they replace.

Built withClaude Codev0ReplitReactFigma
PropDev calculator summary screen showing investor and owner returns

The opportunity

Baby Boomers will pass on an estimated $70–90 trillion over the next decade, much of it in single-family homes. Heirs sell about 70% of inherited homes, often in neighborhoods the next generation can’t afford. The same lot can hold 6–10 units, each priced well below the old house but worth more together.

How the deal works

  1. Find aging owners on well-zoned lots
  2. Partner before the sale
  3. Raise project capital
  4. Rebuild at 6–10 units
  5. Sell below local home prices

Try the calculator

Model construction financing, a seller-financed note back to the homeowner, and traditional build vs. prefab, across the Property, Development, Summary and Ownership tabs.

Open full screen

Costs, modeled bottom-up

At 6–10 units per lot, small per-unit cost swings compound fast, so pricing is built system by system rather than per square foot. Here is one system: all-electric heating and hot water for a 6-unit building, net of rebates and tax credits.

6-unit example, 2025–26 pricing
SystemProject totalPer-unit avg.
Ducted heat pump HVAC$74,500 – $174,000~$12,400 – $29,000
Heat pump water heaters$18,300 – $44,400~$3,050 – $7,400
Net after incentives~$86,000 – $201,000~$14,300 – $33,500

The same approach covers structure, sitework and soft costs, so the per-unit price can be defended line by line to capital partners and to owners trusting the model with their land.