Glass Wool Blanket Insulation

Glass wool blanket is a flexible roll or batt of bonded glass fibers used to insulate HVAC ducts, wall cavities, pipe racks and equipment. DonFoil supplies it plain or faced with FSK, PSK or MSK foil laminate, across a range of densities for thermal and acoustic control.

Technical specifications

PropertyTypical for glass woolDonFoil grade data
MaterialGlass fiber with thermosetting resin binderBy grade
FormFlexible roll or battRoll and batt
DensityAbout 10 to 48 kg/m3 by gradeOn request
Thermal conductivity (lambda)About 0.030 to 0.044 W/(m*K) typicalOn request
Fire classificationNon-combustible, Euroclass A1 / ASTM E84 Class A (fiber)By grade
Facing optionsFSK, PSK, MSK, or unfacedAll options
Common dimensionsRoll 0.6 to 1.2 m wide, 5 to 30 m longOn request
Temperature rangeAbout -50 to 250 C depending on binderOn request

Figures marked typical reflect common glass wool values. DonFoil grade-specific density, lambda and dimension data is supplied on request or with the product data sheet.

What glass wool blanket is

The blanket is made by bonding fine glass fibers into a flexible mat with a thermosetting resin. It bends and drapes over curved surfaces, which is why it is the standard form for ducts and pipe racks. Because the fibers are springy, the blanket holds its thickness without a rigid backing.

Where glass wool blanket is used

HVAC duct wrap is the main use, with the foil or kraft side placed toward the conditioned space. It also fills wall and ceiling cavities, wraps pipe racks and equipment, and is used for acoustic infill where sound control matters. For exposed ductwork it is usually shipped FSK or PSK faced so the foil works as both the vapor retarder and the finish.

Facing options

FSK facing is the general choice for HVAC and ductwork. PSK is used where a polypropylene scrim is preferred, and MSK gives a metallized finish. Plain, unfaced blanket is supplied when a separate jacket or weatherproof layer is already specified. See FSK facing, PP scrim kraft facing and MPET scrim kraft facing for the laminate details.

Installation notes

Lay the foil or kraft side toward the conditioned space and secure the blanket with facing, insulation pins or wire. Overlap the joints and seal every seam with FSK tape rated UL181B. Keep the roll off standing water and do not compress it, because compression raises the thermal conductivity.

Common mistakes

Compressing the blanket into a tight space raises lambda and cuts the insulation value. Leaving gaps at joints and fittings breaks the thermal and vapor line. Storing the roll wet lowers performance and can promote corrosion on the metal behind it. Using it on a surface above the binder temperature chars the resin, and omitting a vapor-facing on chilled lines lets condensation form on the outside.

Standards

Glass wool blanket is supplied to ASTM C795 for industrial use, and to EN 13162, BS 3958 and AS/NZS 4858 for building applications.

Related glass wool forms

Related: Glass Wool overview, Glass Wool Board, Glass Wool Pipe sections.

Request a specification or sample.

Frequently asked questions

Yes. The fiber mat absorbs sound, and a higher-density grade is specified where acoustic control is the main goal.

It depends on the wall build-up and the target R-value. Confirm the grade with your project specification. DonFoil density data is on request.

Wrap the foil or kraft side toward the conditioned space and secure it with facing, pins or wire, then seal the seams with FSK tape rated UL181B.

Yes. Cut with a sharp blade or insulation knife, slightly oversize so it presses into the cavity without gaps.

On exposed HVAC it is usually shipped FSK or PSK faced so the foil acts as both vapor retarder and finish. Plain is used when a separate jacket is specified.