Foil Seam Tape
Foil Seam Tape is a pressure-sensitive aluminum-foil tape formulated to bond directly to the foil facing on Insulated Foil MLV and foil-faced acoustic underlay. It closes every joint airtight so the barrier layer behaves as a continuous sheet, blocks flanking paths at overlaps, and stays flexible through seasonal temperature swings. Peel-and-stick — no primer, no cure time, no waiting to close up the assembly.
- Purpose-Built for Foil Facings: Bonds permanently to the aluminum face on Insulated Foil MLV and foil-backed underlay — the correct tape when the seam surface is foil, not vinyl.
- Airtight Seal at Every Joint: Closes overlaps and butt seams so barrier assemblies perform as a continuous sheet — no leaks around your mass layer.
- Peel-and-Stick Install: Cut, align, and J-roll. No primer, no cure time, and no waiting before finishing the assembly overhead or underfoot.
- Heat & Vapor Tolerant: Aluminum face resists heat and vapor drive — safe next to mechanical, HVAC, and radiant-floor assemblies.
- Long-Term Adhesion: High-tack acrylic adhesive resists edge lift for the design life of the assembly.
Online orders up to 100 rolls. For anything larger, call (415) 864-4440 and we'll price the project with you.
Foil Seam Tape Specifications
- Facing
- Aluminum foil
- Adhesive
- Pressure-sensitive acrylic
- Width
- 2"
- Roll Length
- 55 yd (165 ft)
- Coverage
- ≈ 300 sqft of seam per roll
- Application
- Seals Insulated Foil MLV and foil-faced underlay seams
- Service Temperature
- -20°F to 250°F
- VOC
- Low — no curing required
- Compatibility
- Insulated Foil MLV, foil-faced acoustic underlay, foil vapor barriers
Foil MLV pipewrap
- Composition
- 1 lb/ft² Foil-Faced MLV bonded to 1" quilted fiberglass
- Nominal Thickness
- 1"
- Standard Roll Size
- 48" W × 30' L
- Areal Weight
- 1.22 lb/ft²
- Temperature Range
- -20°F to 350°F
- Fire Rating
- ASTM E84 Class A — FS 12.5 / SD 19.5
- STC (barrier only)
- 29 (1"), 30 (2")
- Seam sealer
- Foil Seam Tape (2" × 55 yd)
- Use with
- Tape every foil-faced overlap and termination airtight
Foil Seam Tape Project Calculator
Enter the total sqft of Insulated Foil MLV or foil-faced underlay to seam — we'll size the 2" × 55 yd roll count at 1 roll per 300 sqft. The 10% buffer only activates once 2 or more rolls are needed.
One roll of Foil Seam Tape (2" × 55 yd) seals approximately 300 sqft of Insulated Foil MLV or foil-underlay seam. The +10% buffer only turns on when 2 or more rolls are needed for full coverage.
STC Gauge
Compare how the Foil Seam Tape performs across assembly tiers. Select an assembly below to see the resulting STC score.
Foil MLV rolls butted edge-to-edge without tape — small gaps and vibration at overlaps drop effective STC.
- STC 30-39: Loud speech clearly audible next room.
- STC 40-49: Loud speech muffled — normal residential wall.
- STC 50-59: Loud speech barely audible; suitable for offices & multi-family.
- STC 60+: Approaches studio-grade isolation.
How Foil Seam Tape compares
| Model | Primary Use | Facing | Roll Size | Notes |
|---|---|---|---|---|
| Foil Seam Tapethis | Insulated Foil MLV & foil underlay seams | Aluminum foil | 2" × 55 yd | Lightweight; ideal for shorter runs & corners |
| Reinforced Foil Seam Tape | Foil MLV seams on long/overhead runs | Scrim-reinforced foil | 3" × 150 ft | Extra strength for demanding spans |
| Vinyl Seam Tape | Standard MLV & drywall seams | Matte PVC vinyl | 2" × 150 ft | Not for foil-faced barriers |
Applicable Assemblies
See where the Foil Seam Tape fits — from budget baseline to studio-grade isolation.
Best — Insulated Foil MLV with every seam foil-taped, sandwiched between drywall and clips + channels
Every foil MLV overlap is centered and taped so the barrier layer performs as a continuous sheet.
Better — Floor underlay with all foil-faced seams taped under finished flooring
Taped foil-underlay seams eliminate joint leaks under LVP, engineered wood, and floating floors.
Good — Insulated Foil MLV added over ceiling drywall with foil-taped seams
Even a simple retrofit performs better when foil MLV seams are taped rather than butted.
