Expansion Joints are a component in seamless rain gutter systems designed to protect the gutters from the effects of thermal expansion. Thermal expansion is the tendency for a material to expand and contract when exposed to changes in temperature.
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According to SMACNA, the best way to protect your gutter system from thermal expansion is to split any long run into two separate runs, capping both ends and leaving ¼” gap between the top edges of the end caps. Then secure a small piece of aluminum to one of the end caps and fold it over the gap so that all rainwater over that gap is directed into either gutter.
Extra Keywords: Splice, Connect