DELTA®-TRELA Vapor Permeable Underlayment

The Problems

Metal roofs and cladding are not sealed to the roof deck or sheathing, which allows moisture to easily get underneath the metal.

If moisture is allowed to accumulate under the metal, two problems can arise. The first is that moisture can prematurely damage the roof substructure, requiring removal of the metal and repair. The second problem is that moisture can condense on the underside of the metal, which can lead to corrosion, requiring the metal to be replaced sooner than necessary. 

The Solution

DELTA®-TRELA is a vapor permeable underlayment with structured separation and drainage, specifically designed for metal roofs and façades with metal cladding. The underlayment prevents corrosion and moisture accumulation underneath panels, ensuring the longevity of your metal roof. 

Product Details
Product Benefits
  • 8mm high randomly oriented studded fiber mat
  • Fiber mat is thermally bonded to a vapor permeable, watertight fabric, based on DELTA®-VENT S 
  • 8mm studded fiber mat ventilates the underside of the metal panels
  • Drainage course – studded structure reliably channels residual moisture to the exterior
  • Vapor permeable, watertight fabric ensures airtightness and allows moisture within the roof cavity to escape via diffusion
  • Rattling noise from rain or hail is reduced by up to 15dB
  • Installed parallel to the eaves, with the studded structure facing upwards, the next section of membrane is overlapped in shingled fashion, ensuring that water is shed to the exterior
  • Burled, studded texture provides a non-slip surface during installation
  • One-step installation, faster and easier than applying an underlayment and a separation layer in independent steps, saving time and money on project schedules
  • Included with every roll is a package of 120 DELTA®-SEALING NAILS used for fastening 

Additional Resources

Guide Specifications

Installation Guides

Product Details

Safety Data Sheets

Technical Data

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