Box Gutter Expansion Joint

Box Gutter Expansion Joint

“Stretch And Seal” Roof Flashing System

Expandable edge strip flashing in grey EPDM.

  • Flashes hi-rib and standing-seam profiles
  • Stretch and form to fit and seal
  • Flash between dissimilar materials
  • Ideal for square ducts, chimneys, skylights
  • 20-year warranty
  • Available in 9″ width by 12′, 33′ and 50′ lengths

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Box Gutter Expansion Joint


If you need expandable edge strip flashing, go with quality you can trust: Box Gutter Expansion Joint from Marco. Ideal for square ducts, chimneys, skylights and more, our Box Gutter Expansion Joint flashes hi-rib and standing-seam profiles. It stretches and forms easily to fit and seal, even between dissimilar materials including brick, fiber cement, galvanized steel, aluminum, stainless steel, and concrete. And with our Box Gutter Expansion Joint, vibration and expansion are not a problem. Available in 9” width by 12’, 33’ and 50’ lengths, Box Gutter Expansion Joint comes with a 20-year warranty and the peace of mind you get with all Marco-quality products.


Base Material: Cross-linked EPDM (Ethylene Propylene Diene Terpolyene)
Color: Grey
Test Level: 3
Test Temperature: B 100° C
Volume Swell: Not required
Durometer Hardness: 60 +/- 5 (shore) (ASTM D 2240)
Tensile Strength: 8MPA (1160 PSI) minimum (ASTM D 412)
Ultimate Elongation: 200% minimum (ASTM D 412)
Heat Resistance:
Heat aging 70 hrs @ 100° C
Change/hardness max. +/- 15 units
Change/tensile max. +/- 15%
Change/ultimate elongation max. 40%
(ASTM D 573)
Compression Set: Maximum 35 % (ASTM D 395B)
Ozone Resistance: 70 hrs @ 38° C @ 50 PPHM 100% quality retained (ASTM D 1171)
Low Temperature Brittleness: Non/brittle 3 minutes N @ -40° C (ASTM D 2137)
Z1, Target Hardness: 60 shore +/- 5 specific hardness (ASTM D 2240)
Z2, Specific Rubber: Specific elastomer EPDM
Z3, Tear Resistance: 100 PPI minimum tear die C (ASTM D 624)
Z4, De-Colorization: Discoloration resistance (ASTM D 1148)
UV Resistance: Excellent
Resistance to Aging: Excellent
Non-Staining: Pass
Z5, Proprietary Specifications: Not listed

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Installation Question?

Easy, One Person Installation

Step 1

For square ducts, chimneys, and skylights: Expand one edge and use separate strips, lapped and joined, to seal around the penetration.

Step 2

For large round pipes: Flash in one step, stretching the lower edge to fit. Join using fasteners or sealant.

Step 3

After installation, and preferably after a period of weathering, Box Gutter Expansion Joint can be painted with any quality 100% acrylic paint after priming with an epoxy resin-based primer.