Double Bubble Foil/White: The Metal-Building Workhorse
If you walk into a newer metal shop, barn or poultry house and see a bright white ceiling, there is a good chance it is a double bubble foil/white liner. It is the product we sell most for steel and post-frame buildings, and it comes with a full set of tested values. Here is what is in the roll and what the numbers mean.
What it is
Two layers of closed polyethylene air bubbles sit between a reflective metallized (MPET) face and a white, UV-stabilized, fire-retardant polyethylene face. The reflective face goes toward the heat source, usually the roof or wall panels, and the white face becomes the finished interior.
Specifications
| Property | Value | Standard |
|---|---|---|
| Thickness | 5/16 in (7.9 mm) nominal | |
| Weight | 0.044 lb/ft² (215 g/m²) | |
| System R-value | R-17.2 (RSI 3.03), heat flow down | ASTM STP1116 method |
| Fire rating | Class A / Class 1, both faces and taped joint | ASTM E84-24 / E2599 |
| Flame spread / smoke | Foil face 0 / 30 · White face 0 / 5 | ASTM E84-24 |
| Water vapor permeance | 0.01 perm initial, 0.04 after humidity aging | ASTM E96 (Method A) |
| Emittance (MPET face) | 0.04 | ASTM C1371 |
| White face UV resistance | 97% tensile strength kept after 500 h | ASTM G154 / D882 |
| Service temperature | −61 °F to 180 °F (−51 °C to 82 °C) | |
| Puncture strength | 60 lb/in | |
| Roll widths | 4 to 8 ft (1.22 to 2.44 m) | |
| Roll length | 125 ft (38.1 m) |
Why contractors like it
- One product does three jobs: reflects radiant heat, acts as a vapor retarder against condensation on the steel, and gives a finished white ceiling.
- Wide rolls, up to 8 ft (2.44 m), mean fewer seams on long roof and wall runs.
- Plenum-level fire performance: 0 flame spread on both faces and smoke well under the limit of 50.
- No fibers, no itch, and it does not absorb water.
Where it goes
- Metal buildings and post-frame buildings (roofs and walls)
- Poultry and livestock houses
- Barns, equipment sheds and shops
- Garages and storage buildings
Install tips
- Keep an air space of at least 3/4 in (19 mm) on the reflective side.
- Overlap sheets by at least 2 in (51 mm).
- Seal every seam with white tape on the white face, so the liner works as a continuous vapor retarder.
- Seal edges and penetrations before the panels or trim go on.
Questions we get asked
Can the white face stay exposed?
Yes. It is UV-stabilized and fire retardant, and it kept 97% of its tensile strength after 500 hours of UV exposure (ASTM G154 / D882).
Is it a vapor barrier?
It is a vapor retarder: 0.01 perm initially and 0.04 perm after humidity aging (ASTM E96). Tape every seam to keep it continuous.
What sizes are available?
Widths from 4 to 8 ft (1.22 to 2.44 m) on 125 ft (38.1 m) rolls. The common stock sizes are 4, 6 and 8 ft wide; other widths are made to order.
See the full spec sheet and roll sizes on the Double Bubble Foil/White page, or request a delivered quote.