Customer focused services
K. Guller Insulation installs thermal and acoustic insulation on commercial HVAC duct systems — flexible duct wrap, internal duct liner, and rigid board — sized to meet IECC and ASHRAE 90.1 requirements. We also install listed fire-rated duct wrap on kitchen grease exhaust and ventilation ducts where a rated enclosure isn’t practical. Union Heat & Frost Insulators perform all work across Pennsylvania, New Jersey, and Delaware.
Under the IECC and ASHRAE 90.1, supply and return ducts generally require R-6 to R-12 depending on location — ducts outdoors or in unconditioned attics need the most, ducts in conditioned space may need none — and cooled ducts also need a vapor retarder to prevent condensation.
| Duct location | Typical requirement | Notes |
|---|---|---|
| Exterior / rooftop | R-8 to R-12 | Weatherproof jacketing; vapor-sealed if cooled |
| Unconditioned attic or space | R-6 to R-12 | Highest exposure to condensation risk |
| Indirectly conditioned (plenums, shafts) | R-1.9 to R-6 | Per adopted code edition |
| Conditioned space | Often exempt | Liner may still be specified for acoustics |
| Duct location | Typical requirement | Notes |
|---|---|---|
| Exterior / rooftop | R-8 to R-12 | Weatherproof jacketing; vapor-sealed if cooled |
| Unconditioned attic or space | R-6 to R-12 | Highest exposure to condensation risk |
| Indirectly conditioned (plenums, shafts) | R-1.9 to R-6 | Per adopted code edition |
| Conditioned space | Often exempt | Liner may still be specified for acoustics |
Exact values depend on the code edition adopted in your jurisdiction and the climate zone (most of our footprint is Zone 4A/5A). Our estimators price to the spec section — typically 23 07 13 (duct insulation) — and flag conflicts between drawings and code before they become RFIs.
Many projects combine all three; the spec and the acoustic requirements decide. If the drawings are silent, we’ll recommend the assembly that meets code at the lowest installed cost — and put it in writing.
Yes. Where a Type I kitchen exhaust duct can’t be enclosed in a rated shaft, we install listed flexible enclosure systems (fire-rated duct wrap) tested to ASTM E2336, providing the code-required rating in as little as 1.5–3 inches of thickness. The same family of listed wraps covers ventilation and hazardous-exhaust ducts requiring an hourly rating. Every installation follows the specific listing — layers, overlaps, banding, and penetration details — and we document the system for the AHJ.
A cooled duct running through humid unconditioned space is a condensation machine: surface temperatures below the dew point mean sweating ducts, stained ceilings, wet insulation that no longer insulates, and mold complaints. The fix is the right thickness of insulation plus a continuous sealed vapor retarder — taped and mastic-sealed FSK facing with no gaps at hangers, joints, or damage points. This is craft-sensitive work, which is why apprenticeship-trained insulators matter more on cold systems than anywhere else.
Find answers to common questions about our services, processes, and how we work with clients across various industries.
Typically R-6 to R-12 depending on duct location and the adopted code edition — exterior and attic ducts need the most, and ducts fully inside conditioned space are often exempt. Cooled ducts also require a sealed vapor retarder.
Duct wrap is installed on the outside of the duct for thermal performance and condensation control; duct liner is installed inside the duct and provides both insulation and sound absorption.
Sometimes. Return ducts in unconditioned spaces generally require insulation under the energy code; returns within conditioned space usually don’t, unless the spec calls for liner acoustically.
Usually a failed vapor retarder on a cooled duct — humid air reaches the cold metal, condenses, and soaks the insulation. Wet fiberglass loses its R-value and should be replaced, not dried in place.
KG Insulation installs duct wrap, liner, board, and fire-rated duct wrap on commercial projects across eastern PA, NJ, and DE from Lafayette Hill, PA. Call (610) 941-9394.
