Renovating an Existing Idaho Home vs. Building Custom: The $1M Decision
Renovating an Existing Idaho Home vs. Building Custom: The $1M Decision
You own a home in Idaho that you love. It's on great land. The location is perfect. But it doesn't perform. It's cold in winter. It costs $300 per month to operate. The air quality isn't great. You're considering a major renovation.
Or you're considering demolishing and building custom.
Which makes financial and practical sense? Let me walk you through the math, and why the answer surprises most people.
The Renovation Approach: What It Costs
Let's say you have a 2,500 square foot home on 5 acres in the Boise foothills. It's a conventional 1990s build. R-20 walls. Standard HVAC. Conventional finishes. You love the land. The location is perfect.
A major renovation to make it high-performance would include:
Exterior wall insulation: Spray foam or rigid insulation applied to the outside of the home. Cost: $40,000 to $60,000. But you're still dealing with the original wall cavity moisture issues. You've only addressed the outside.
HVAC replacement: New heat pump system, new ductwork, new controls. Cost: $25,000 to $40,000.
Window replacement: Remove existing windows, install high-performance triple-pane. Cost: $35,000 to $50,000.
Interior finishes: Remove and replace drywall, paint, cabinetry with natural materials. Cost: $60,000 to $100,000.
Roof inspection and potential replacement: If roof is near end of life, replacement cost: $30,000 to $50,000.
Foundation and structural assessment: Surprises often emerge. Budget: $15,000 to $30,000.
Permits, inspections, contingencies: Idaho county permits for major renovation. Cost: $10,000 to $20,000.
Total renovation cost: $215,000 to $350,000.
And the home still isn't as good as a custom build. The wall system is better, but not R-45. The HVAC is modern, but not passive solar integrated. The finishes are improved, but not naturally vapor-permeable. You've spent a quarter-million to half-million dollars and you still have a compromised building science approach.
The Custom Build Approach: What It Costs
Now you demolish the 1990s home and build custom on the same 5 acres. You keep the land you love. You build a new straw bale home designed for that specific site.
New custom home, 2,800 square feet: $1.4M to $1.8M depending on finishes and complexity.
Site work and utilities (already there): Minimal cost, since utilities already serve the location. $20,000 to $40,000.
Demolition of old home: $15,000 to $25,000.
Total new build cost: approximately $1.5M (or roughly $535 per square foot for a high-performance home).
Yes, that's more than the renovation. But let's look at what you're actually comparing.
The Real Financial Comparison
Renovation: $215K to $350K. Result: compromised 1990s home with modern systems and insulation upgrade. Still 50 percent more energy consumption than a straw bale home. Utility cost: $150 to $200 per month.
Custom build: $1.5M. Result: R-45 straw bale home with passive solar, integrated systems, net-zero capable design. Utility cost: $30 to $80 per month.
Over 30 years:
Renovation cost (initial + utilities + maintenance): $215K to $350K + ($1,800 to $2,400 per year in utilities) + ($8,000 to $15,000 in mechanical maintenance) = roughly $590K to $800K over 30 years.
Custom build cost (initial + utilities + maintenance): $1.5M + ($360 to $960 per year in utilities) + ($1,000 to $2,000 in mechanical maintenance) = roughly $1.62M to $1.78M over 30 years.
Wait. The custom build costs more over 30 years, right?
No. You're missing the actual comparison.
The Real Story: Land Value and Legacy
The renovated home is still a 1990s home with upgrades. Resale value will be 80 to 90 percent of total investment (maybe $500K to $700K). You've spent $590K to $800K and you own a home worth $500K to $700K.
The custom home is a new high-performance home on land you love. Resale value will be 95 to 100 percent of construction cost (approximately $1.5M to $1.8M). You've spent $1.62M to $1.78M and you own a home worth $1.5M to $1.8M.
More importantly, you own a home that will serve your family for 100+ years. The renovated home will need another major renovation in 20 to 30 years. The custom home won't. You're building for generations, not for the next decade.
The Decision Framework
Choose renovation if: You want to preserve the existing structure, you have budget constraints, you're not planning to live there long-term.
Choose custom if: You want the land but not the existing building, you're building for generational use, you care about performance and health, you want a home that won't need major renovation in your lifetime.
For a $1M+ decision on Idaho land you love, custom build often makes more sense than renovation. You get the land. You get the location. You get a home built to last and perform.
