This article covers advanced methods, materials, and considerations for metal cladding underlayment and thermal break layers in modern construction.
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Expanded Guidance
This article on Metal Cladding Underlayment and Thermal Break Layers includes key strategies for envelope continuity, product selection, code compliance, and typical failures to avoid. Systems are described with links to example products and performance tips based on field conditions.
🔍 Recommended Products
- Flashing Tape:Â 3M All Weather Flashing Tape
- Sealant / Liquid Flashing:Â Tremco ExoAir Liquid Flashing
- Thermal Insulation / Spacer:Â Rmax Polyiso Board
Best Practice Tips
- Ensure compatibility with adjacent layers and substrates
- Sequence flashing and weather barriers shingle-style
- Use mockups and field adhesion tests before bulk installation
- Coordinate across trades to maintain control layer continuity
Combining WRBs and Thermal Breaks
Metal cladding systems often combine water-resistive barriers with thermal break layers like mineral wool or foam boards. Use z-girt spacers thermally isolated from structural framing. When using underlayment or synthetic WRBs, verify their maximum service temperature against dark metal solar exposure.
Role of Underlayment in Metal Cladding Systems
Underlayment layers beneath metal panels protect against moisture intrusion and control air and vapor movement. In rain-exposed assemblies, use a water-resistive barrier (WRB) that also acts as an air barrier. Options include mechanically fastened building wraps, peel-and-stick membranes, or fluid-applied WRBs depending on exposure and structural substrate.
Thermal Bridging in Furring and Framing
Metal clips and furring can become significant thermal bridges in continuous insulation assemblies. Interrupt the thermal path using plastic thermal spacers, fiberglass brackets, or thermally broken z-girts. Some systems use offset clips with stand-off screws to reduce direct conductive contact between cladding and structure.
Common Thermal Break Systems
- Thermally Broken Z-Girts:Â Continuous insulation support with polymer inserts
- Clip-and-Rail Systems:Â Support brackets with non-metallic isolators for ventilation
- Horizontal Hat Channels with Spacer Tape:Â Cost-effective option when used over insulation
Fire Resistance and Moisture Drainage
Ensure WRBs and thermal break systems comply with NFPA 285 and allow vertical drainage in back-ventilated façades. Drainage mats or grooved insulation can facilitate air movement and drying behind panels. Avoid using closed-cell foams without venting behind dark metal claddings which reach high surface temperatures.
Installation Tips and Long-Term Durability
Always follow the metal panel manufacturer’s detailing requirements for underlayment compatibility and fastening patterns. Use stainless steel fasteners and check that furring is aligned and level. Periodic inspection is necessary to identify dislodged panels, sealant breakdown, or underlayment exposure over time.
