You can use cellulose and fiberglass fibers in the form of wet sprays to insulate open wall, ceiling and floor cavities; they are an alternative to more expensive sprayed foam insulation, especially high and low density polyurethanes.
Be aware anyway. Sprayed foam insulation has advantages of their own.
Spray insulation foams and fibers can be used in both new construction and retrofits.
Spray fibers (cellulose and fiberglass) are loose-fill insulation products mixed with a solution of glue and water, designed to adhere to the surfaces of walls or ceilings.
Spray foams, on the other hand, involve polyurethane resins or other similar products; they are designed to combine with blowing agents (CO2, HCFC….) during the installation; the combination expands into a plastic foam, largely composed by gas molecules, with excellent insulation value.
High and low density polyurethanes
Polyurethane foams come as high-closed-cell high-density or as open-cell low-density products.
Low density products have a spongy texture and are filled with air (instead of CO2 as high-density products); they have a lower R-value and are less expensive.
Sprayed foams and fibers require special blower equipment (often truck-mounted blowers, in the case of foams).
Sprayed foam installation is a professional job.
Price of Spray Foams and Spray fibers
Spray foams are a more expensive than fibers, depending on their density and type.
For high-density polyurethane, expect prices above $1 per square foot for each inch of thickness.
The R-value of cellulose and fiberglass sprays are very similar to loose-fill products, installed in close cavities; the R-value of high-density polyurethane can double that of cellulose and fiberglass sprays:
- polyurethane low-density: R-3,7 per inch of thickness
- polyurethane high-density: R-6,5 per inch of thickness
Spray fibers vs. Spray Foams
Spray fibers are cost-competitive, but they have a lower R-value and the best of them (sprayed cellulose) is very moisture sensitive. Most of all, fibers do not have the versatility of the polyurethane sprays - they do not have the ability of polyurethane to expand and fill small and obstructed cavities.
Spray foams have excellent adhesiveness, good air sealing capacity and higher structural strength than sprayed fibers – and also a higher insulation value (high-density foams).
Polyurethane foams are very versatile materials. They provide excellent R-value due to the way they expand and fill cavities.
They are very moisture-resistant; they do not absorb water and they have a very low water vapor transmission.
Sprayed Foam insulation vs. Foam Insulation Boards
Spray foams mold to the shape of cavities and expand quickly, sealing and filling the cavities efficiently - an ability that rigid boards do not have.
Hence their different uses: sprayed foam insulation is largely used to insulate cavities, while polystyrene and polysocyanurate are largely used as insulating sheathing materials.
Disadvantages of polyurethane and foam Insulation sprays
Spray foams are more expensive than most other insulation materials.
They have to be protected from EV radiation, and require special equipment to be installed.
Low-density Insulation foams vs. high density Insulation foams
Low-density foams keep their R-value over time (about R-3.5 per inch), contrary to high density foams. They are cheaper, fire-resistant and flexible: they expand quickly, sealing and filling the cavities easily; there are also slow expanding foams intended for cavities in existing buildings; they reduce the chance of damages due to over-expansion.
Polyurethane professional associations and Constractors
Websites of associations dealing with polyurethane products:
Basf listing of polyurethane organizations.
Polyurethane foam association (USA),
Polyisocyanurate Insulation Manufacturers Association
Spray Polyurethane Foam Alliance (SPFA).
Spray Polyurethane Association
Finding contractors and installers:
Insulation Contractors Association of America Contractor Locator.
Blow-in-Blanket Contractors Association Contractor Locator (North America)
Resnet insulation contractors USA