How to Install Asphalt Shingles Over a Metal Valley
- 1). Shingle in a continuous row across the valley. With this method, the metal valley is hidden by shingles, accomplished by shingling in one direction from one roof section only.
- 2). Apply black roof sealant across the middle of the valley to seal the shingles--rather than nails---and nail only at the edges of the valley, with an additional vertical line of sealant between the nail edges and the valley center.
- 3). Snap a horizontal chalk line on the roof section past the valley to line up your shingles and keep your rows consistent with the valley angle.
- 4). Alternatively, shingle both roof sections from the outer edges to meet just across the valley. Run a vertical bead of black roof sealant on the metal within a couple of inches of the edges, place shingles and nail them only in the area between the sealant and metal edge. The center of a valley is never nailed and is always protected by sealant.
- 5). Snap a chalk line from roof ridge to the bottom of valley on both sides of the valley curve. Cut along the chalk line with your hooked blade, to expose the metal valley. The width of the valley is an aesthetic choice; you may prefer a narrow 4-6 inch valley or a wider valley for greater ease of roof litter runoff. Widen the valley at the bottom edge to prevent water or ice build-up.
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