Unroll a length of roofing felt -- sometimes called felt paper or tar paper -- along the bottom edge of the cupola roof. Pull out only as much as needed for the side of the roof that is facing you, leaving a couple of inches of overhang at the beginning edge. Cupolas vary widely in roof shapes -- from domes to traditional two-sided roofs and a wide variety of geometric shapes -- so the exact shape of your cupola's roof determines how many roof faces you work with.
Align the felt with the bottom edge of the roof, allowing it to overhang slightly. Leaving a half-inch of excess material is preferable to having a gap without underlayment, where moisture may penetrate and ruin the decking underneath.
Use an industrial-grade staple gun to attach the roofing felt as you spread the material across the roof face. Space the staples about 8 inches apart. Stop where the roof face ends or where another face joins the one you are working on, such as with a hexagonal roof. Leave a couple of inches of extra underlayment at the ending edge.
Cut the roofing felt, using a utility knife, to end the first row of felt. Spread a second row if needed; roofing felt is 3 feet wide, so cupolas of that height or higher will need additional rows. Overlap the felt about 6 inches vertically -- 3 or 4 inches horizontally if you must piece any felt together. Attach and cut each row similarly, ending at the peak of the roof and allowing a slight overhang.
Switch to additional roof faces as you complete each side. Continue allowing extra underlayment to overhang each edge, both top and bottom, along with where roof facings meet, if applicable.
Trim each edge once all the felt paper is secure. Cut the bottom edges flush with the bottom of the roof, working carefully, and treat the roof facing edges similarly if you have a two-sided cupola roof. For geometrically shaped roofs, tuck the ends smoothly over each other to ensure that where the faces join are completely covered. Staple the edge of the outer layer of felt to secure it.
Spread a bead of roof tar along the lower, bottom edge of the cupola roof. Apply roughly a 12-inch-long bead and lay it about a half-inch back from the roof edge to ensure it doesn't squeeze out once you place a shingle.
Use a utility knife and a straightedge to cut the tabs -- the tooth-shaped shingle portion -- free from the solid portion of a three-tab asphalt shingle to create a starter strip. Turn the solid portion of the shingle upside down and place it over the tar, allowing the shingle to hang a half-to three-quarters of an inch past the roof's bottom edge.
Continue across the roof edge facing you, spreading a line of tar and attaching shingle starter strips, similarly to a skirt. Nail each in place with 4 nails, spaced an inch from either end and 2 inches toward the center of the shingle.
Cut shingles down to a miniature size if you are shingling a small cupola of less than 3 or 4 feet wide. Measure and mark each shingle, on the top and bottom of the shingle face, every 3 inches. Thus, a three-tab shingle yields nine 4-inch-wide shingles -- three per tooth-like tab -- with both the shingle and upper, solid portion. Increase or decrease the size, if preferred, and cut apart with a utility knife.
Dab a spot of roof tar near the lower, middle portion of each shingle. Align the first shingle with the bottom corner edge of the roof. Do not allow it to overhang from either the bottom or the side edge. If the side edge adjoins another roof face, leave the slightest gap to ensure the shingles do not press against each other when complete.
Nail the shingle in place with two nails, one on either side of the shingle, through the middle portion of the shingle. Continue securing the first row of shingles, laying a bead of tar along the end of the roof space. Do not leave space between adjacent shingles or force them against each other.
Secure each additional row similarly, leaving about 2 1/4 inch of shingle exposed below each successive row. Stagger the shingles for each row, cutting the first shingle of the row narrower -- only if needed -- to create the staggered joint and trimming the end of the row as necessary. Work each roof face similarly.
Fold a piece of metal flashing around the peak of any cupola other than a two-faced roof. Make a cone-shaped covering and mark the flashing where excess material juts out beneath the rest. Cut the flashing with metal cutters or tin snips.
Place the metal roof cap around the roof peak again, squeezing a bit of roof adhesive underneath before pressing into place. Drive a nail through the seam where the flashing edges meet.
Center a 4-inch shingle over each joint where a roof face meets another. Dab a spot of tar on the lower portion of the rear of the shingle. Press and fold the shingle down over either face. Nail in place. Continue working up the joint, leaving a 2 1/4-inch overlap for each. These form the ridge caps. The same method can be used for the peak cap, but it will be bulkier and will not look as good.
Things You Will Need
- Roofing felt
- Industrial-grade staple gun
- Utility knife
- Roof tar or adhesive
- Roofing nails
- Metal cutters or tin snips
- Metal flashing
- A waterproofing underlayment or other specialty roofing underlayment may substitute for roofing felt. Install as directed by the manufacturer.