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.
