USA Insulation vs Blown Fiberglass — Which Costs Less

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USA Insulation vs Blown-in Fiberglass — Which Costs Less

I spent three months last year comparing insulation quotes for my 1,500 square-foot attic in Portland, Oregon. Two contractors kept coming back to the same matchup: spray foam from USA Insulation or standard blown-in fiberglass. The prices were wildly different, and so were the claims about energy savings. I wanted the actual math—not marketing speak. Here’s what I found, and where each product actually wins.

Cost Comparison at Installation

Let’s start with what installers are actually quoting right now.

USA Insulation spray foam (open-cell, R-3.6 per inch) typically costs between $1.50 and $2.10 per square foot installed in the Pacific Northwest, depending on whether existing insulation needs removal. For a 1,500 square-foot attic getting R-38 in a 10.5-inch application? You’re looking at $2,250 to $3,150 in material and labor combined.

Blown-in fiberglass (R-3.2 per inch) runs $0.65 to $1.10 per square foot installed—netting and labor included. Same 1,500 square-foot attic at R-38 requires about 12 inches of settled depth. You’re budgeting $975 to $1,650 total.

This is where most people stop. They see $1,200 difference and pick fiberglass. But honestly, that’s not the full picture.

Cost per R-value achieved matters more than cost per square foot. The actual numbers:

• USA Insulation: $2,700 average install ÷ 38 R-value = $71.05 per R-value point
• Blown-in fiberglass: $1,312 average install ÷ 38 R-value = $34.53 per R-value point

Blown-in costs roughly 49% less per R-value upfront. Contractors don’t advertise this number because fiberglass installers don’t need to justify premium pricing. USA Insulation installers do.

Regional labor changes everything here. In Seattle, spray foam labor runs about 15% higher than Portland due to stricter moisture management codes. Rural Eastern Oregon? Neither option gets competitive pricing—you’re paying travel time. The Willamette Valley has five foam contractors competing, which pushes prices down 8-12% from what I’m quoting as the PNW average.

Energy Savings — 10 and 20 Year ROI

Probably should have opened with this section, honestly. The upfront cost difference evaporates when you calculate actual heating and cooling savings.

I’m using Portland, Oregon climate data: 4,400 heating degree days annually, modest cooling load (Portland doesn’t have brutal summers). My assumptions: $0.13 per kWh electrical rate, 3% annual inflation, 15-year HVAC system life, comparing replacing old or missing attic insulation with new material.

An uninsulated 1,500 sq ft attic loses roughly 1.2 BTU per hour per square foot per degree of temperature difference. That’s about 15,000 BTU/hour heat loss at a 20-degree inside-outside differential on Portland’s coldest winter day.

Annual heating cost with no attic insulation: approximately $1,680. With R-38 blown-in, that drops to $340 annually—a $1,340 savings per year. With R-38 spray foam, it drops to $285 annually—a $1,395 savings per year.

The spray foam saves you an extra $55 per year in heating due to better air sealing. Blown-in has gaps at edges and around penetrations. Cooling benefit is negligible in Portland, but head to Sacramento or Boise, and spray foam’s sealing properties add another 5-8% efficiency gain in summer.

10-year ROI calculation:

• Blown-in fiberglass: $1,312 install + ($340 × 10 years) = $4,712 total cost. Energy savings: $13,400.
• USA Insulation spray: $2,700 install + ($285 × 10 years) = $5,550 total cost. Energy savings: $13,950.

Net benefit after 10 years: blown-in is $1,388 cheaper when you factor in the lower upfront cost. Hold the home for 15 years? Spray foam catches up. At 20 years, spray foam is $1,200 ahead because compound energy savings outpace the initial premium.

Here’s the assumption nobody talks about: I’m using a conservative 3% annual inflation rate for electricity. If we see 4% inflation (more realistic given PNW hydroelectric supply tightness), spray foam breaks even at year 14 instead of year 18.

Application Differences That Affect Cost

Labor is why spray foam costs more. One installer can blow 2,000-3,000 square feet of fiberglass in a day. Spray foam? That requires two people, specialized equipment (compressor, heated hose, HVAC-rated PPE), careful mixing and application. A 1,500 sq ft attic takes a skilled crew four to six hours, versus one person six to eight hours for blown-in. The math is brutal.

Moisture management matters too, especially in western states. Spray foam (open-cell) is vapor-permeable and won’t trap moisture against the roof deck. Blown-in fiberglass is hydrophobic but allows moisture to pass through—meaning you still need proper attic ventilation. Seal the eaves wrong, and you trap condensation under blown-in, which degrades R-value over time. Spray foam doesn’t have this problem because it air-seals the entire cavity.

Fiberglass settling is real. Lab testing shows 5-10% R-value loss over 15-20 years as fibers compress under their own weight. A perfectly installed R-38 blown-in system becomes R-34 to R-36 by year 15. Spray foam doesn’t settle—it stays stable across decades.

This isn’t marketing. It’s applied physics. Loosely packed fibers compress under pressure and vibration. Dense-pack blown-in (higher cost) slows this, but standard loose-blown absolutely settles.

Where USA Insulation Wins (and Loses)

Spray foam wins if:

• You’re in the home for 15+ years and can absorb upfront cost
• Your attic has complex geometry, rim joists, or rim-to-sill sealing needs—spray foam handles these better
• You live where HVAC zoning matters. Spray foam seals ducting leaks that blown-in won’t address
• You’re adding conditioned space (a catwalk for storage or a future bedroom) where air leakage ruins comfort
• You don’t have ventilation concerns. Some homes with very tight vapor barriers need permeable insulation; this isn’t your case

Blown-in fiberglass wins if:

• You’re budget-constrained and breaking even on cost in 10 years is acceptable
• The attic is already clear and flat. No removal needed, simple install
• You might move within 12 years. Payback period favors the cheaper option
• Off-gassing concerns matter to you. Spray foam emits isocyanates and other VOCs. Ventilation resolves this, but it’s real
• You want to add more insulation later. Blown-in stacks easily; spray foam needs careful edge sealing

The honest verdict: Choose USA Insulation spray foam if your home payoff window is 15+ years and energy ROI is a priority. The extra efficiency compounds. Choose blown-in fiberglass if you’re under that payback timeline or if upfront cost is the controlling factor. Both products work — spray foam just works harder and costs more to install that extra work.

Questions to Ask Your Contractor Before Choosing

Don’t let a single quote decide this. Ask these questions to both contractors:

• What’s your actual R-value in my climate? PNW contractors sometimes quote R-value for standard conditions (70°F) but don’t account for attic temperature extremes, which affect performance slightly. Get the number specific to your location.
• Is removal of old insulation included? If you have existing fiberglass, removal adds $200-$600 depending on attic size and condition. This changes the spray foam ROI clock.
• What’s the settling prediction for your blown-in product? Honest contractors admit 5-8% loss over 20 years. Budget for that.
• Are local building codes moisture-sensitive? Some PNW jurisdictions—especially coastal areas—require open-cell foam or rigid barriers to manage humidity. Portland and Salem are generally flexible; Corvallis can be strict. Check your code first.
• What off-gassing timeline should I expect? Open-cell spray foam typically off-gasses for 24-48 hours. If you have kids under two or respiratory sensitivities, ask about low-VOC products. They exist and cost 10-15% more.
• Warranty differences? USA Insulation warrants spray foam for 80 years. It doesn’t degrade, so this is legitimate. Fiberglass warranties are usually 15-25 years. Understand what’s covered.
• Can I add more later? Blown-in is easy to add. Spray foam requires careful sealing at edges if you go back in. Matters if you’re phasing work.

One final thing: I called three Portland-area contractors for actual 2024 quotes while writing this. Prices varied by 18-22% even among certified installers. Shop around, get written specs on R-value achieved (not just installed thickness), and don’t trust verbal cost estimates. Get three quotes minimum.

The real cost difference between these products isn’t blown-in versus spray foam. It’s whether you’re optimizing for year-one expense or year-20 comfort. Know which one you’re actually buying, then the choice becomes obvious.

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