Add to cart Straps for 5″ Downspout, Galvalume $2.00 These 26 gauge Galvalume straps measure 21″ x 2.25″ and fit 5″ downspout. We recommend two straps for one-story and three straps for a two-story installation. They can be screwed to the house, wrapped around the downspout and screwed in the front. Another method is to wrap the strap over the front of the downspout and screw on both sides. A rosette or fleur-delis can be used in either situation.