FAQ — Benefits & Performance

Performance+ Earthwool 1000 Pipe Insulation can be used where pipe temperatures range from 0°F and 1000° F (-18°C to 538°C).

Fiberglass batts are manufactured in many R‑values between R-8 to R-29 to accommodate needs by region and structure. For example. low‑density batts provide about R‑11 in 3½‑inch walls, while high‑density batts offer R‑15 in the same cavity. For wood construction, options range from R‑11 to R‑49. Batts intended for attics generally go from R‑30 to R‑60. Be sure to use the R‑value required by your code and climate.

Yes. Fiberglass insulation helps reduce noise by absorbing sound and limiting how much travels through walls, ceilings, and floors. Knauf fiberglass insulation products include sound performance ratings that show how much sound they absorb. Adding insulation can make rooms quieter and more comfortable. However, insulation alone does not make a space completely soundproof as it works together with other materials to reduce sound transmission.

According to the EPA's Energy Star program, air sealing and insulation can reduce heating and cooling costs by around 15% and total energy bills by 11%. Fiberglass insulation slows heat transfer, helping HVAC systems operate more efficiently and lowering utility costs. Combining insulation with duct sealing maximizes savings.

Yes. Adding Knauf fiberglass insulation to warehouse roofs, walls and ducts reduces heat gain and loss. Fiberglass’s low thermal conductivity and wide range of R‑values help maintain stable indoor temperatures, decrease HVAC loads and lower energy costs.

Many contractors prefer formaldehyde‑free products because they reduce odors and improve indoor air quality. Knauf’s ECOSE technology uses a bio‑based binder and is GREENGUARD Gold certified, simplifying code compliance and appealing to health‑conscious contractors and clients.

Knauf fiberglass insulation resists heat transfer by trapping air within its fine glass fibers, creating a barrier that slows the movement of heat. Its low thermal conductivity helps maintain stable temperatures and reduce energy loss. Knauf’s rigid fiberglass boards and pipe insulation are designed to perform in operating temperatures up to 850°F (454°C), helping protect mechanical systems, reduce surface temperatures, and improve energy efficiency in both hot and chilled water applications.

Potentially. Proper installation of fiberglass insulation can reduce heating and cooling costs by about 15% (according to ENERGY STAR). Knauf Performance+ fiberglass insulation slows heat transfer, helping you’re home maintain its indoor temperature which helps your HVAC system run less.

Yes — fiberglass insulation is widely used to reduce sound transmission between rooms and from outside the building. Its fibrous structure absorbs airborne sound waves, reducing both noise transfer through wall and floor assemblies. Learn more about insulating for sound.

No — fiberglass insulation is not classified as fireproof, but most Knauf fiberglass insulation products meet stringent fire safety standards required by national building and mechanical codes. Unfaced Knauf fiberglass batts are noncombustible per ASTM E136 and do not require added fire-retardant chemicals. Most Knauf products achieve a flame spread index of 25 or less and a smoke developed index of 50 or less under ASTM E84 testing. Note:  Kraft facing on batt insulation is not fire rated and must not be left exposed. Refer to the product documentation library for specific surface burning characteristics by product.

Fiberglass insulation is inorganic and does not support mold growth on the fiberglass itself. Knauf fiberglass products are tested under ASTM C1338 (Standard Test Method for Determining Fungi Resistance of Insulation Materials and Facings) and meet the standard’s resistance criteria. However, like any building material, accumulated dust and dirt can support mold growth if it becomes wet and remains damp. Proper assembly design with appropriate vapor retarders, drainage planes, and moisture management is essential to prevent mold in any assembly. Keep fiberglass insulation dry during storage, installation, and use.

Payback period for insulation depends on building type, climate zone, energy costs, baseline assembly performance, and the R-value upgrade being evaluated. In commercial construction, insulation upgrades typically pay back through reduced HVAC energy consumption, smaller equipment sizing, and improved occupant comfort. Because these variables interact, generic payback figures are unreliable. For project-specific ROI, energy modeling tools such as ASHRAE 90.1 compliance software or whole-building energy simulation (e.g., EnergyPlus, eQUEST, IES VE) produce accurate payback estimates by modeling the proposed assembly against the project’s actual energy loads and utility rates. For Knauf product thermal performance data to support energy modeling, see our product data sheet library.

Yes — Knauf fiberglass insulation products are engineered to meet the fire safety requirements of the International Building Code (IBC), International Mechanical Code (IMC), and NFPA 90A/90B for commercial construction. Unfaced fiberglass batts are noncombustible per ASTM E136, and Knauf products are tested for surface burning characteristics under ASTM E84. Many Knauf fiberglass products are also included in UL-listed fire-resistance-rated assemblies for walls, floor-ceilings, and roof-ceilings. For UL assembly listings by construction type, see our UL Assemblies resource. For product-specific fire ratings, consult the relevant product data sheet.

Fiberglass insulation has a low thermal conductivity (k-value), typically ranging from 0.23 to 0.34 BTU·in/(h·ft²·°F) depending on product density, type, and form. Lower k-values represent better thermal resistance — Knauf rigid boards and pipe insulation fall near the low end of this range, while standard batt products fall toward the higher end. This range translates to approximately R-2.9 to R-4.3 per inch of installed thickness under ASTM C518 test conditions. Specific k-values vary by product. For exact thermal conductivity data, consult individual product data sheets.

Product selection for acoustic performance depends on which acoustic metric the assembly is designed to achieve:

For sound transmission between rooms (STC): Standard-density unfaced fiberglass acoustical batts installed in wall, floor-ceiling, and ceiling cavities reduce sound transmission by absorbing sound energy within the cavity. STC performance is determined by the full assembly — including framing, sheathing, gypsum layers, and decoupling — not by the insulation alone. Knauf fiberglass batts are included in UL-listed and independently tested STC-rated wall and floor-ceiling assemblies.

For reverberation control within a room (NRC): Surface-applied fiberglass boards or blankets with high NRC ratings reduce reverberation by absorbing sound that strikes the wall, ceiling, or surface. This is the appropriate approach for mechanical rooms, gymnasiums, large open spaces, and other rooms where in-room reverberation is the acoustic concern.

For STC-rated assembly listings and NRC-rated product specifications, consult individual product data sheets or our acoustic performance resource. For project-specific acoustic design questions, contact Knauf Technical Support.

Acoustic performance of building assemblies is evaluated using different metrics depending on what the assembly needs to do:

Sound Transmission Class (STC) measures how well a wall or floor-ceiling assembly blocks airborne sound transmission between rooms. STC is a property of the full assembly — framing, sheathing, gypsum layers, insulation, and decoupling — not of the insulation alone. STC is tested under ASTM E90 and classified under ASTM E413.

Impact Insulation Class (IIC) measures how well a floor-ceiling assembly blocks impact sound such as footfalls. IIC is also an assembly-level metric, tested under ASTM E492.

Noise Reduction Coefficient (NRC) measures how well a surface-exposed material absorbs sound striking its surface — relevant to reverberation control within a room, not to sound transmission between rooms. NRC is tested under ASTM C423.

For STC and IIC performance of Knauf-included assemblies, consult tested assembly listings. For NRC-rated acoustic products designed for surface-applied reverberation control (such as mechanical room treatment), see our acoustic performance resource. For project-specific acoustic design questions, contact Knauf Technical Services.

Knauf High-Density (HD) EcoBatt® fiberglass products are engineered for assemblies where cavity depth is limited but higher R-values are required. For example, R-15 HD is designed to achieve R-15 performance in a standard 2×4 wood-frame wall cavity, and R-30 HD is designed to achieve R-30 performance in cathedral ceiling assemblies with limited depth for ventilation clearance. Each Knauf product is tested under ASTM C518 and labeled with its rated R-value at the specified thickness in accordance with the FTC R-Value Rule. For complete product specifications and tested R-values, consult individual product data sheets.

Fiberglass insulation can support multiple LEED credits across the Energy & Atmosphere, Materials & Resources, and Indoor Environmental Quality categories. Knauf fiberglass products contribute through improved building energy performance, third-party-verified Environmental Product Declarations (EPDs), material ingredient disclosure through Health Product Declarations (HPDs) and Declare Labels, recycled content, and low-emitting material certifications. Many Knauf fiberglass products are GREENGUARD Gold certified, supporting Indoor Environmental Quality credits related to low-emitting materials. Specific credit contributions vary by LEED version, project type, and product. For project-specific credit documentation, EPDs, HPDs, and certification letters, see our sustainability documentation hub or contact Knauf Technical Services for credit-specific support.

Both unfaced fiberglass batts and rock mineral wool are classified as noncombustible under ASTM E136, and both can achieve ASTM E84 flame spread index ≤25 and smoke developed index ≤50 — the surface burning characteristics required by most national building and mechanical codes. Faced fiberglass products (such as kraft-faced or FSK-faced batts) are not classified as noncombustible per ASTM E136 due to the facing, though FSK-faced products are engineered to meet ASTM E84 fire requirements.

Service temperature ranges differ between product categories. Standard building insulation in both materials is intended for normal building envelope temperatures. For high-temperature industrial applications, some commercial and industrial fiberglass insulation products are rated for service temperatures up to approximately 1000°F under ASTM C411, while rock mineral wool generally tolerates higher continuous service temperatures.

Product selection should be based on the specific assembly, service temperature, code requirements, and tested fire-resistance-rated assembly listings. For Knauf product fire performance data, consult individual product data sheets.

Yes — fiberglass duct wrap, duct liner, and air duct board provide both thermal resistance and acoustic absorption in HVAC systems, which is why they are widely specified in commercial and residential mechanical applications. Thermal performance reduces energy loss through duct walls and helps control condensation, while the fibrous structure absorbs airborne noise generated by air movement and equipment. Specific R-values and acoustic performance ratings vary by product, thickness, and facing. For Knauf duct wrap, duct liner, and air duct board specifications, consult individual product data sheets.

Yes — fiberglass insulation is commonly specified in residential interior walls, floor-ceiling assemblies, and ceilings to improve acoustic performance. Its fibrous structure absorbs airborne sound energy within the cavity, reducing sound transmission between rooms. For floor-ceiling assemblies, fiberglass also contributes to impact sound performance when paired with appropriate assembly construction. Acoustic performance is rated by Sound Transmission Class (STC) for airborne sound and Impact Insulation Class (IIC) for impact sound, both tested at the assembly level. For STC and IIC ratings of Knauf-included assemblies, see our acoustic performance resource.