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Roofing Materials

Water Leakage

Problem: Water leakage of metal roofing.

Cause: Thermal movement.

Metal has a high co-efficient of expansion. As metal expands, it can increase the size of the perforation in the metal. When it contracts, the exposed fastenings may loosen

Solutions: Use proper anchoring systems.

  • The best way to control thermal movement is a concealed anchor-clip system without perforations, such as sliding hook clips or bar clips. This system securely fastens the sheet metal to the roof deck or structure while accommodating thermal movement as shown in Figures 16a and 16b.

Metal Siding Before Zip Closure

Figure 16a - Metal Siding Before Zip Closure

Metal Siding After Zip Closure

Figure 16b - Metal Siding After Zip Closure
  • Avoid using exposed bolts or screws through the metal. Thermal movement of sheet metal cannot be prevented. Use special fastenings which allow the sheet metal to move freely as it expands and contracts.
  • Properly install neoprene seals under fasteners.
  • Ensure fasteners are installed straight.

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