Shingle application depends upon whether or not the existing roofing has been removed or left in location and on the kind of roofing material left in place. If the old roofing has been removed or if reroofing is over old roll roofing or BUR, the shingle-application procedures are the exact same as those for new construction. Wooden shingle roofs which are modified with feathering strips also are shingled within the very same manner as new construction.
The scenario that differs from new construction will be the application of new strip shingles over existing strip shingles. The nesting process, described earlier, minimizes any unevenness that may well result from the shingles bridging over the butts of the old shingles. It also ensures that the new horizontal fastening pattern is 2 inches below the old one. The nesting process is based on the assumptions that the new roofing method has a five inch exposure along with the existing roofing was installed with a 5 inch exposure and effectively aligned.
If new eaves flashing has been added, snap chalk lines on it to guide the installation of the new shingles until the courses butt against the existing courses.
For the starter course, take away the tab plus two inches or a lot more from the top of the starter strip shingles so that the remaining portion is equal in width to the exposure of the old shingles, which is normally five inches. Apply the starter strip to ensure that it really is even together with your existing roof eave. If self-sealing shingles are employed for the strip, locate the factory-applied adhesive along the eaves.
Be sure the existing shingles overhand the eaves far sufficient to carry water into the gutter. If they do not, cut the starter strip to a width which will do so. Do not overlap the existing course above. Get rid of three inches from the rake end of the very first starter strip shingle to make sure that joints between adjacent starter strip shingles are covered when the very first course is applied.
For the first course, cut at least two inches from the butts of the very first course of shingles so that the shingles fit between the butts of the existing third course as well as the eave edge of the new starter strip. Commence at the rake with a full-length shingle. Use 4 fasteners per shingle, locating them inside the identical positions as in new construction. Do not fasten into or above the factory-applied adhesive.
Use full-width shingles for the second and all successive courses. Eliminate 6 inches from the rake end of the first shingle in each and every progressive course, through the sixth. Repeat the cycle by starting the seventh course having a full length shingle. Place the best edge of the new shingles against the butt edge of the old shingles within the course above.
Making use of the full width on the second course reduces the exposure of the very first course to three inches, but this region is generally concealed by gutters as well as the look should not be objectionable. For the remaining courses, the five inch exposure is automatic and coincides with that of the existing shingles. As in new construction, apply the shingles across the diagonal as you proceed up the roof.