Prior to installing new shingles on any roof, the roof surface must be properly prepared. The old shingles and underlayment should be completely stripped. Any rotted or damaged roof sheathing must be replaced, and new underlayment and drip edge installed before installing new dimensional shingles. It is always better to completely tear off and start fresh because a tear off/re-roof will last longer and perform better than a shingle layover.
Tools and Materials Needed for Installing Dimensional Shingles
– Dimensional shingles and starter shingles.
– Utility knife with roofing hook blades.
– Tape measure, pencil and speed square.
– Hammer and nails (or roofing nailer and coil nails). Nails should be 1 1/2″ long or longer.
– Chalk line and chalk.
– Ladder.
Directions for Installing Dimensional Shingles on a Simple Gable Roof
1. These instructions assume a proper roof surface preparation, including drip edge, ice and water shield and felt paper installed properly and to code.
2. Begin by installing the starter shingles. Simple starter shingle rolls can be purchased, or three-tab shingles or even dimensional shingles with the tabs cut off can be used. Three-tab shingles turned upside down work great, because they are a bit shorter than dimensional shingles, and they have a consistent height which allows the installer to snap a line to keep the course straight.
3. Take a measurement of the height of the starter shingles and snap a line allowing the starter course to extend over the end of the drip edge by 1/2″. For example, many three-tab shingles are 12 inches tall, so in this case the line would be 11 1/2″ above the drip edge bottom. Run a full course of starter shingles across the eave, extending them 1/2″ over the gable edges (the same as the eave edge). Extending the shingles past the drip edge on all sides gives the roof extra protection from rain water getting in under the shingles during extreme weather.
4. Next, prepare the entire face of the roof for quick and efficient installation by snapping all remaining lines. Beginners may choose to snap lines for every course all the way up the gable. Others may feel comfortable snapping lines every second or fourth. Regardless, it is important to carefully figure the measurements for each line from the bottom, for the sake of accuracy. For example, a certain brand of dimensional shingles is 13 1/4″ tall, with 5 5/8″ exposure on each course. This means the first line would be snapped at 13 1/4″ from the leading edge of the starter shingle, the next at 18 7/8″, and so on.
5. The lines indicate where the top of each shingle course should line up. They help the installer to keep the courses straight, preventing wavy lines and exposed nail heads. It may be beneficial to convert measurements into decimal form and run the numbers on a calculator, then transfer them to a piece of paper or cardboard to work off of from the roof. After doing calculations once, keep the numbers handy, for they will be used again and again for the entire roof job. There is no sense in doing the same mental work twice.
6. Once all lines are snapped, begin installing the shingles. Many installers prefer to work several courses at once while working across a roof face, to save time and effort. Try to decide how many courses will be covered at once prior to starting roofing, and keep this information in mind when snapping lines. For example, snapping a line every fourth course is extremely helpful if working four courses at a time, because each time across the roofer has a chance to make sure the lines are staying straight.
7. If running six courses at a time, for example, start with a full shingle on the first course, then cut off 6 1/2″ from the first shingle on the second course, then 13″ off the first shingle on the third course, and so on. Keep the cut off pieces, as they will work perfectly to either finish the courses on the other end or start new ones. Determine how much to cut off each shingle when starting the courses based on how many courses will be covered at once. For example, covering four courses at once, an installer could cut off 9 1/2″ off the first shingle on the second course and so on, and start with a full shingle again to begin the fifth course.
8. Keep working up the gable all the way to the top, following the lines and properly dealing with walls using 8×8 flashing cards. Each shingle course should get a card installed prior to the shingle being installed against the wall, with 4 inches under the shingle and 4 up the wall. Ideally, ice and water shield and felt paper should be run up any walls behind the siding as well, as an extra precaution against leaks.
9. Work up the opposite gable towards the ridge, then properly ventilate and shingle over the ridge, following installation and exposure instructions for the vents and the ridge shingles. Any exposed nails should be caulked and all left over roofing materials brought down. All loose siding and flashing materials should be permanently secured to weatherproof the entire roof.
