Start with the starter course along the eaves
The first row of shingles you install goes along the bottom edge of your roof, called the eaves. This row is called the starter course, and it runs the entire length of the roof edge. You nail it upside down — the adhesive strip faces up — so that when you install the first full course of shingles above it, the adhesive from those shingles bonds to the starter course and holds everything in place.
Snap a chalk line about 11 inches up from the edge of the roof to mark where the top of the starter course should sit. This measurement accounts for the overhang you want at the eaves. Cut starter shingles from regular three-tab shingles by removing the tabs, leaving only the strip with the adhesive. Nail each starter shingle with four nails, placing them about 1 inch down from the top edge and spaced roughly 12 inches apart across the width of the shingle.
Key Takeaways
- The starter course runs upside down along the eaves and creates the adhesive bond that holds the first full course in place.
- Snap chalk lines every 5 inches up the roof to keep rows straight, because shingles shift easily if you eyeball alignment.
- Nail each shingle with four nails placed 5.75 inches up from the bottom edge, staying within the nailing zone marked on the shingle.
- Offset each row by half a shingle width so the seams do not line up vertically, which weakens the roof and lets water run straight down.
- Work from the bottom up and from one side to the other, completing one full row before moving to the next.
Snap chalk lines to keep rows straight
Roofs are not perfectly flat, and your eye will not catch small angles. Chalk lines keep rows parallel to the eaves and prevent the roof from looking wavy once you are done. After you finish the starter course, snap a chalk line 5 inches up from the top of the starter course. This marks where the top of your first full course of shingles will sit.
Continue snapping lines every 5 inches up the roof until you reach the ridge. The 5-inch spacing accounts for the 5-inch exposure — the part of each shingle that shows — on a standard three-tab shingle. If you are using architectural or dimensional shingles, check the manufacturer's instructions for the correct exposure and adjust your line spacing.
Install the first full course with offset
The first full course starts at the bottom of your first chalk line. Begin at one corner — typically the left side — and work across. Before you nail the first shingle, cut 6 inches off the left edge. This creates the offset that prevents seams from lining up vertically between rows, which is critical for water shedding and structural strength.
Align the top of the first shingle with your chalk line and nail it with four nails. Place the nails 5.75 inches up from the bottom edge of the shingle, in the nailing zone (the area between the tabs). Space the nails roughly 12 inches apart horizontally. Lay the next shingle to the right, overlapping the previous one by about 1/2 inch, and nail it the same way. Continue across the entire roof.
Offset each subsequent row by half a shingle
The second full course starts with a full shingle (no cut). The third course starts with a shingle cut 6 inches shorter. The fourth starts with a full shingle again. This pattern — full, cut, full, cut — staggers the seams so water does not run straight down the roof. Some roofers use a different offset pattern; check your shingle manufacturer's instructions for their recommendation.
Align each row with your chalk line, nail with four nails in the nailing zone, and overlap each shingle by about 1/2 inch. Work your way up the roof one complete row at a time. Do not jump around or try to fill in gaps later — working systematically prevents mistakes and keeps the roof watertight.
Nail in the correct zone to avoid leaks
The nailing zone on a three-tab shingle is the area between the tabs, usually marked with a light-colored band. Nails placed outside this zone can miss the roof deck or penetrate the adhesive strip, both of which cause leaks. Place all four nails 5.75 inches up from the bottom edge of the shingle. If you nail too high, you risk hitting the shingle above and creating a weak spot. If you nail too low, the nail may miss the roof deck entirely.
Use roofing nails — typically 1.25 inches long — and drive them straight in, not at an angle. The nail head should sit flush with the shingle surface, not sunk into it. A nail driven too far can tear the shingle and create a leak point. If you miss the deck or drive a nail at an angle, remove it and use a new hole nearby rather than trying to straighten it.
Handle the ridge and roof edges
When you reach the ridge (the peak of the roof), the last full course of shingles will extend past the peak. Trim these shingles so they sit flush with the ridge line. Cut ridge cap shingles from standard shingles by cutting them into three pieces, each about 12 inches wide. Fold each piece over the ridge and nail it with two nails on each side of the ridge, placing them about 5.75 inches from the top of the cap.
For the sides of the roof (the rakes), trim the last shingle in each row so it sits flush with the edge. You can cut shingles with a utility knife or a circular saw. Seal the cut edges with roofing cement to prevent water from entering the exposed fiberglass mat underneath.
Seal seams and exposed nails in high-wind areas
In areas with high winds or heavy rain, explore a small dab of roofing cement under the bottom edge of each shingle to bond it to the course below. This is not always necessary in calm climates, but it adds durability in harsh weather. If any nail heads are exposed — for example, where shingles overlap at the rake — seal them with roofing cement to prevent water from running down the nail shaft into the roof deck.
Let the adhesive strip on the shingles cure for at least 24 hours before walking on the roof or exposing it to heavy rain. In cold weather, the adhesive may take longer to set. Check the manufacturer's instructions for cure time in your climate.
Frequently Asked Questions
What if my roof has valleys or dormers?
Valleys (where two roof planes meet) and dormers (roof structures that stick up) require special flashing and careful shingle placement. Shingles in valleys should be cut and sealed with roofing cement to direct water down the valley. Flashing — metal or rubber strips — should be installed under the shingles at the valley before you lay shingles. This is more complex than a straightforward roof and may warrant professional installation.
Can I install shingles in cold weather?
Shingles have an adhesive strip that bonds when warm. In temperatures below 50°F, the adhesive does not set up, and shingles may not seal properly. If you must roof in cold weather, you can warm shingles in the sun or use roofing cement under each shingle to bond it manually. Check your shingle manufacturer's cold-weather instructions.
How many nails do I need per shingle?
Standard three-tab shingles require four nails per shingle. Some manufacturers recommend six nails in high-wind areas. Check your shingle package or the manufacturer's website for the specific requirement for your product.
What happens if I nail outside the nailing zone?
Nails outside the nailing zone can miss the roof deck, tear the shingle, or penetrate the adhesive strip, all of which cause leaks. If you place a nail incorrectly, remove it and drive a new nail in the correct location. Do not leave the misplaced nail in the roof.
Do I need to remove old shingles before installing new ones?
You can install new shingles over one layer of old shingles in most cases, which saves time and money. However, if the old shingles are curled, cracked, or missing, or if there are already two layers of shingles on the roof, you should remove the old layer first. Removing old shingles also lets you inspect the roof deck for damage.