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Standard Underlay

BLM Standard Underlay is a non-woven, crimped filament poIyester, needle punched to allow air to circulate freely between the underside of the Lead Sheet and timber board decking with penny-air gaps, preventing condensation forming and corroding the underside of the Lead Sheet.
Standard Underlay
BLM Standard Underlay also serves to smooth out timber board substrate surfaces allowing the Lead to expand and contract with ease.
BLM Standard Underlay:
  • Allows Lead to breathe, preventing condensation forming and corroding the underside of the sheet
  • Protects against imperfections in timber board substrates, allowing the Lead to expand and contract freely during thermal movement
  • Resistant to high temperatures
  • Prolongs the life of correctly fitted Lead Sheet
  • Standard Underlay should be laid in adjacent sheets, either abutted or overlapped, across the fall of the roof
  • Must be fitted over the whole substrate area
  • All Rolled Sheet over 600mm wide should have an underlay fitted
  • Smaller widths may require an underlay depending on the application
  • Avoid forming joints above underlay
  • Not recommended for use when laying lead on to Plywood substrates
Dimensions:
  • 25m x 1.0m rolls

A Product Data Sheet providing handling, use and storage advice can be found on the download below

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