The calculator
Run the spray foam vs blown-in vs hybrid comparator
Pick the area, square footage, your priorities, and budget tier. The comparator runs all three approaches (spray foam, blown-in, and the flash-and-batt hybrid) and ranks them against your stated goals.
Your project
According to the International Energy Conservation Code, “the 2021 IECC (R402.1.2) sets attic insulation minimums at R-49 to R-60 for Climate Zone 5B, which covers the Denver metro area.”
How this works
How does the spray foam vs blown-in vs hybrid comparator work?
The comparator scores each approach against your stated goals (max R-value, air sealing, low cost, long-term performance, sound reduction), then applies a budget modifier and an area-specific bias (rim joist work favors foam regardless of budget). The winner is whichever scores highest.
Cost ranges use 2026 Denver-metro contractor pricing: spray foam $2.50-$5.00 per sq ft, blown-in $1.50-$3.00, hybrid $1.80-$3.60. Removal of existing material adds $1.50-$3.50 per sq ft for foam and hybrid (foam adheres only to bare deck), and $0.50-$1.50 for blown-in (often goes over existing). Calibrated as of May 2026.
According to the Building Performance Institute, “effective ceiling-plane air sealing requires bare-deck access — old loose-fill insulation must be removed to identify and seal air leakage paths through the ceiling.”
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Get a Quote Based on Your Numbers
30 seconds to fill out. We'll send your inputs along with the quote request so the contractor knows what you've already calculated.
We've Got It. Here's What Happens Next.
We've got your info. A local pro is reviewing it now. Expect a call within a few hours, or by tomorrow at the latest. While you wait, here's what to look for in the quote you receive: (1) R-value target — current Colorado code is R-49 to R-60 for attics, anything less is under-spec. (2) Air sealing scope — insulation alone does nothing if air leaks aren't sealed first. (3) Rebate handling — Xcel rebate paperwork should be handled for you, not by you. (The federal IRA Section 25C credit expired in 2025 and Colorado HEAR closed for the Front Range — Xcel programs are now the active rebate stack.) (4) Removal scope — pre-1990 homes often need old insulation removed before new install. If a quote skips all four, get another quote.
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According to the Department of Energy, “loose-fill cellulose insulation typically settles 15-20% over its lifetime, reducing effective R-value at the same nominal depth.”
Frequently asked
What do Denver homeowners ask about this calculator?
Should I use this calculator if my home was built after 2010?
Possibly — but interpret the output cautiously. Post-2010 Denver homes were built to recent code, so most calculator scenarios assume pre-1990 baselines and may overstate the project value for newer homes. If your bills are normal and your comfort is fine, the honest answer is usually: hold the money. The 10-15 year mark is when even code-compliant homes start showing settled batts.
Do you handle new construction insulation?
We focus on retrofit insulation for existing Denver homes. New construction insulation typically goes through your general contractor or builder, and the process is different — pricing structures, code compliance steps, and project timing all work differently for new builds. If you're working on a new build, we can refer you to a partner with new-construction experience.
When does spray foam actually earn its premium?
Three scenarios: rim joists and small targeted air-sealing applications (premium per sq ft is small in absolute terms); vaulted ceilings or conditioned-attic conversions (foam adheres to roof deck, blown-in can't); and homes with chronic cold-spot or wind-infiltration issues that air sealing alone won't solve. For typical attic top-ups in pre-1990 Denver homes, blown-in is usually the right call.
What is flash-and-batt hybrid?
Two-layer install: closed-cell spray foam goes on the deck (typically 1.5-2 inches for ~R-13 and continuous air sealing), then blown-in cellulose or fiberglass batts fill the rest of the cavity to reach the R-value target. You get the foam's air-sealing benefit at the deck — where most attic-plane leakage occurs — at roughly 60-70% of full-foam cost.
Does spray foam off-gas or have indoor air quality issues?
During cure, yes — standard practice is to vacate the home for 24 hours after install with active ventilation. Modern formulations cure faster than 15+ years ago, but the chemistry is real. Once cured, no off-gassing. Reputable installers schedule cure time and ventilation explicitly. People with respiratory sensitivities should extend the vacate window 48-72 hours.
Can I use spray foam without removing existing insulation?
No. Foam adheres to the structural deck and surrounding framing — it can't be applied over loose-fill or batt material because the bond fails. Plan on removal as a separate scope before any foam install. The exception is rim joist work, where there's typically no existing insulation to remove.
Does the comparator account for Xcel rebate differences between approaches?
Indirectly. All three approaches qualify for the Xcel Insulation and Air Sealing Rebate when meeting program R-value targets. Spray foam often delivers higher R-values per inch, which can affect rebate amount. The Whole Home Efficiency Bonus stacks on all three when bundled with 2+ other measures. Run the Rebate Eligibility Checker for a more detailed breakdown.