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Common penetration flashing problems are:

  • The failure to properly design the flashing for the penetration.
  • Open or broken seams in metal curbs caused by expansion and contraction.
  • Standing water behind penetration curbs caused by the omission of crickets.
  • Sagging or separating base flashings caused by omission of top wood nailers.
  • Missing or deteriorated counter flashing.
  • Splitting or separation of the felt stripping over the edge of metal flanges.
  • Improper priming and stripping of metal surfaces.
  • Fastener backout and separation of the metal flashing flange from the roof around penetration flashings.
  • Movement between stack vents or pipes and the flashing.


The following are potential problems that may decrease the life cycle of the roof system:

  • Blisters and/or large areas of nonadhered membrane
  • Open laps, excessive wrinkles, fishmouth
  • Splits, ridges
  • Fastener backout or pop up against or through the membrane
  • Worn spots (deteriorated areas or holes in the membrane)
  • Differences in firmness of the insulation or substrate
  • Displacement of granules exposing the membrane
  • Lack of or deteriorated surface coating
  • Delamination of foil surfacing
  • Degradation caused by lack of drainage
  • Damage by equipment support
  • Punctures
  • Hail damage
  • Wind damage