Blown-in insulation suits older homes because it easily fits into irregular, hard-to-reach cavities, filling gaps and voids that traditional batt insulation often misses. Its loose-fill nature allows it to conform around pipes, wires, and framing, improving energy efficiency and comfort without extensive renovation. This insulation type offers an efficient upgrade method that minimizes disruption while enhancing thermal performance.
This article provides a detailed exploration of why blown-in insulation works well for older homes, covering types, benefits, technical data, comparisons, decision factors, and common questions. The goal is to offer clear, practical knowledge to help homeowners and contractors understand when and why to choose blown-in insulation for aging structures.
Types of Blown-In Insulation and Their Suitability for Older Homes
Blown-in insulation typically comes in three materials: cellulose, fiberglass, and mineral wool. Each has unique properties affecting performance, cost, and installation suitability in older buildings.
Insulation Type | Material Composition | R-Value per Inch | Fire Resistance | Moisture Resistance | Environmental Impact | Cost per Sq. Ft. (Approx.) |
Cellulose | Recycled paper treated with fire retardants | 3.2 - 3.8 | Moderate (treated with fire retardants) | Moderate (can absorb moisture; must be properly installed) | High recycled content; biodegradable | $0.50 - $1.00 |
Fiberglass | Glass fibers | 2.2 - 2.7 | High (non-combustible) | High (does not absorb moisture) | Low environmental impact but energy intensive production | $0.40 - $0.90 |
Mineral Wool | Rock or slag fibers | 3.0 - 3.3 | Very High (inherently fire resistant) | High (resists moisture and mold) | Moderate environmental impact, durable | $0.70 - $1.20 |
Bonus Tip
Cellulose is often preferred for older homes due to its ability to tightly fill irregular spaces, improving air sealing where gaps and cracks are common.
Why Blown-In Insulation Is Well-Suited for Older Homes
Older homes often have complex framing, uneven wall cavities, and existing insulation challenges. Blown-in insulation excels here because it:
- Fills Gaps Thoroughly: It flows into cracks, voids, and around obstructions, reducing air leaks and cold spots.
- Requires Minimal Structural Changes: Blown-in insulation installs through small holes in walls or attic floors, avoiding costly drywall removal.
- Improves Energy Efficiency: By sealing air gaps and increasing insulation levels, it helps older homes meet modern energy codes and comfort expectations.
Comparison with Other Insulation Types in Older Homes
Feature | Blown-In Insulation | Batt Insulation | Spray Foam Insulation |
Ease of Installation | High (fills irregular spaces) | Moderate (requires removal of drywall, careful cutting) | Moderate to low (professional installation needed) |
Air Sealing Capability | Good (fills gaps, reduces leaks) | Poor to moderate (gaps common) | Excellent (creates airtight seal) |
Cost | Moderate | Low to moderate | High |
Disruption to Home | Low | High (walls often opened) | Moderate |
Moisture Handling | Variable by material | Poor (fiberglass can trap moisture) | Good (closed cell repels moisture) |
Long-Term Settling | Some settling possible | None | None |
Bonus Tip
For older homes with fragile walls, blown-in insulation reduces the risk of damage compared to batt or spray foam installations.
Technical Specifications and Performance Data
Specification | Cellulose | Fiberglass | Mineral Wool |
Typical Installed Density | 2.0 - 3.5 lb/ft³ | 0.5 - 0.9 lb/ft³ | 2.5 - 3.0 lb/ft³ |
R-Value Range per Inch | 3.2 - 3.8 | 2.2 - 2.7 | 3.0 - 3.3 |
Soundproofing Quality | Good | Moderate | Excellent |
Pest Resistance | Low (can attract pests if untreated) | Low | High |
Installation Temperature | Ambient (no special conditions) | Ambient | Ambient |
Market Facts About Blown-In Insulation in Older Homes
- According to the U.S. Department of Energy, retrofitting older homes with blown-in insulation can reduce heating and cooling costs by 15% to 30%.
- The demand for cellulose blown-in insulation has grown steadily due to its environmental benefits and suitability for retrofit applications.
Things to Consider Before Making a Decision
Assess Wall and Attic Condition
Older homes may have damaged or rotted framing or moisture issues. Blown-in insulation requires sound structures to prevent trapping moisture, which could worsen damage.
Air Quality and Ventilation
Ensure the home has proper ventilation, especially when installing cellulose insulation, which can retain moisture if airflow is restricted.
Existing Insulation Type
Removing or supplementing old insulation affects cost and installation complexity. Fiberglass batts underneath may settle or compress with blown-in material.
Cost and Budget Constraints
Blown-in insulation generally offers a mid-range cost but factor in potential repairs or prep work for older homes.
Professional Installation vs. DIY
Blown-in insulation usually requires specialized equipment and professional installation to ensure proper density and coverage.
Common Questions About Blown-In Insulation in Older Homes
How long does blown-in insulation last?
Properly installed blown-in insulation can last 20 to 30 years or more without significant degradation.
Does blown-in insulation prevent drafts?
It reduces drafts by filling gaps better than batt insulation but does not create a perfect air barrier like spray foam.
Can blown-in insulation cause moisture problems?
If installed without proper vapor barriers or ventilation, cellulose in particular can retain moisture and cause mold.
Is blown-in insulation safe around electrical wiring?
Yes, it is non-combustible (fiberglass and mineral wool) or treated for fire resistance (cellulose), but proper clearance and codes must be followed.
What Makes Blown-In Insulation Ideal for Older Homes FAQ
Does blown-in insulation work well in walls with irregular cavities?
Yes, it conforms to the shape of cavities, filling irregular spaces more completely than batt insulation.
Can blown-in insulation be added without removing drywall?
Yes, installers drill small holes in walls or attic floors to blow in insulation, minimizing disruption.
How does blown-in insulation impact energy bills?
It improves thermal resistance and air sealing, typically lowering heating and cooling costs by up to 30%.
Is blown-in insulation environmentally friendly?
Cellulose is made from recycled paper, making it one of the most sustainable options. Fiberglass and mineral wool vary in environmental impact.
What maintenance does blown-in insulation require?
It generally requires little maintenance but should be inspected for settling or moisture issues, especially in older homes.
Make the Right Decision
Blown-in insulation offers an efficient, minimally invasive upgrade to improve the comfort and energy efficiency of older homes. Its ability to fill irregular spaces and reduce air leaks makes it superior to batt insulation in retrofit scenarios. Consider the home’s structure, ventilation, and budget when choosing the best insulation type. Consulting with an insulation professional ensures proper material selection and installation technique, maximizing long-term performance and durability.
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Author and Reviewer:
Author: Bob Gasca attended his first spray foam training in 2007 and has continued to pursue yearly training to stay current with the latest technology and practices. He is a certified Spray Foam Master Installer through the SPFA and a member of the SPFA. Additionally, Bob serves as a Spray Foam Worldwide Ambassador, sharing information with spray foam professionals globally. Recently, he returned from a building science training, where he expanded his knowledge on how weather conditions affect home performance, helping him better diagnose and improve home health for families. Bob specializes in finding solutions to complex moisture and air infiltration issues.
Reviewer: Noah Gonzalez reviewed this article and drew on 9 years of experience to offer suggestions that make the guidance more directly useful for insulation contractors.
