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To begin roofing, first cover the entire roof with a single piece of 15 lb. asphalt-impregnated roofing paper (tar paper). It’s an extra layer of protection that helps ensure the inside of your doghouse remains dry. Staple the roofing paper in place with a hammer stapler or electric stapler, using 3/8-inch galvanized staples. Use a utility knife to trim the edges flush with the edges of the roof panels.
When roofing your doghouse, it’s important that no nail heads protrude into the interior of the house where they could hurt your animal. Be sure to use galvanized roofing nails no longer than 3/4 inches.
The first roofing shingle is your “starter course” and is installed upside down—with the tabs facing up. Keep the front and bottom edges of the starter shingle flush to the bottom and front edges of the roof panel, and nail it in place with roofing nails. The nails go along the nailing line just below the notch in the shingles. Repeat on the other side of the house. Then add a starter course over the front and back edges of the roof, covering the peak. Gently press and crease these shingles so they lay flat over the peak. Allow the front edges of these shingles to overhang the plywood by 3/4” to help protect the plywood edges from moisture.
Install a first row of shingles directly over the starter course, but this time with the shingle tabs facing down. Nail the first course in place. Continue to add rows of shingles, offsetting the notches between the tabs. Three rows of shingles per side will cover the entire roof.
When complete, trim off the excess at the front, back, and along the peak, using a utility knife equipped with a hook blade made for cutting shingles. Be sure to preserve the 3/4" overhang along the front and back roofline.
Cap the ridge using single tabs -- one-third of a shingle cut width-wise along the splits between the tabs. Gently fold each tab in half so that it fits snugly over the peak, and nail in place to cover the ridge of your doghouse. Each ridge cap shingle should overlap and cover the nail heads of the previous shingle. However, the last nail will be exposed, so cover the head with a dab of roofing cement to seal and hide it.