Radiant Barrier for Metal Buildings

Metal roofs respond quickly to solar exposure and can radiate substantial heat toward the building interior. A radiant barrier can reduce that exchange when at least one reflective face borders an air space, but condensation control and the complete roof or wall assembly must be planned together.

Where radiant barrier can be used

• Beneath metal roofing with an adjacent cavity or air space.
• Across the underside of purlins or framing where the reflective face remains exposed to the interior air space.
• In selected wall assemblies with furring or framing that preserves an air space.
• Alongside conventional insulation when both radiant and conductive heat flow need to be addressed.

Choose LP or VB deliberately

Laser Perforated (LP) allows vapor passage and is the more forgiving selection where the assembly needs drying potential. Vapor Barrier (VB) is non-perforated and can serve as part of an intentional vapor- or air-control layer when seams, penetrations, edges, and transitions are detailed for continuity. Climate, indoor humidity, building use, and insulation location all influence that decision.

Installation principles

1. Identify the reflective air space before selecting the attachment method.
2. Keep the material from being tightly sandwiched between two solid layers if radiant performance is expected.
3. Coordinate fasteners and supports so wind or pressure changes do not damage the sheet.
4. Protect required ventilation, drainage, and roof-manufacturer details.
5. Use appropriately rated material and confirm project-specific fire and code requirements.

Why oxidation protection matters around metal construction

Reflective performance depends on the exposed surface remaining low-emittance. Ra-flect uses an oxidation-protected surface intended to preserve its 95% reflectivity instead of relying on a higher initial bare-aluminum claim that may not represent long-term conditions.

Estimate the order

For a simple rectangular roof or wall, calculate each surface area and include overlaps and cuts. For complicated metal-building geometry, use field dimensions for each plane. Wider rolls can speed work across open framing, while narrower rolls may be easier around closely spaced girts, purlins, and obstructions.