Installing shingles yourself is possible if you have the right tools, materials, and safety setup, but it requires careful attention to fastening, overlap, and weather sealing
Roof shingle installation is not a one-person job and not something to rush. You will need a helper, a find ladder or scaffolding, a nail gun or hammer, a utility knife, a tape measure, and roofing cement. The work takes longer than most homeowners expect — a typical single-story roof takes two to three days with two people working steadily. The most common mistakes are driving nails too high or too low on the shingle, leaving gaps between courses, and skipping the roofing cement that seals the shingle tabs.
Before you start, check your local building codes. Some jurisdictions require a licensed roofer for any roof work, and your homeowner's insurance may not cover damage from DIY installation if something goes wrong. If you have an active mortgage, your lender may have restrictions too. If you are replacing shingles on an existing roof rather than doing a full tear-off, the process is simpler but the stakes are the same — a leak that starts small can rot the decking underneath and cost thousands to fix.
Key Takeaways
- Shingles must be fastened with four nails per shingle, placed in the nail line marked on the shingle itself, not above or below it.
- Each course of shingles must overlap the one below it by 5 to 6 inches, and the first course must be offset so seams do not line up vertically.
- Roofing cement under the tab of each shingle is what actually stops water from running underneath — nails alone do not seal the roof.
- You need a helper on the ground to hand materials up and watch for safety; working alone on a roof is how people fall.
- If you are replacing shingles over an existing roof, remove the old shingles completely first — layering new shingles over old ones voids most warranties and shortens the life of the new shingles.
Prepare the roof deck and underlayment
If you are doing a full replacement, remove all old shingles, flashing, and nails down to bare wood. A roofing shovel or pry bar works, but this is the most physically demanding part of the job. Inspect the decking for soft spots, rot, or damage. Any section that feels spongy or looks discolored needs to be cut out and replaced with plywood of the same thickness — usually 1/2 inch or 5/8 inch. A rotten spot under new shingles will only get worse and will eventually cause the shingles to sag or buckle.
Once the deck is solid, install underlayment. Synthetic underlayment (like Titanium UDL or similar products) is more durable and easier to work with than felt, though both work. Lay it horizontally starting at the eaves, overlapping each course by 4 to 6 inches. Staple it down every 12 to 18 inches so it does not shift when you walk on it. At the eaves, the underlayment should extend past the edge of the roof slightly so water drains into the gutter, not behind it.
Install drip edge and flashing
Drip edge is a metal strip that runs along the eaves and gables and directs water into the gutters instead of behind them. Install it before the underlayment at the eaves and after the underlayment at the gables. Use roofing nails spaced 12 inches apart. If you are replacing shingles and the old drip edge is still in good condition, you can leave it, but check that it is not bent or corroded.
Flashing goes around any penetration — a chimney, vent pipe, skylight, or valley where two roof planes meet. If you are only replacing shingles and not touching the flashing, leave it alone unless it is clearly damaged or leaking. If you are installing new flashing, follow the manufacturer's instructions for your specific product. Flashing is where most roof leaks start, so this is not a place to improvise or rush.
Lay out and snap chalk lines for the first course
The first course of shingles sets the pattern for the entire roof. Snap a chalk line parallel to the eaves, 5 to 6 inches up from the edge. This is where the top of your first course will sit. Most roofers use a starter course — a row of shingles installed upside down (with the tabs pointing up toward the ridge) — under the first regular course. The starter course fills the gaps between the tabs of the first course and creates a solid seal at the eaves.
If you are using a starter course, snap a line at the eaves and install the starter shingles with the tabs facing up. Then snap your line 5 to 6 inches above that for the first regular course. Before you nail anything, lay out the first course dry (without nails) to see how it will look at the gable ends. You may need to cut the last shingle to fit, and you want to avoid ending with a very narrow piece if you can. Adjust your starting point if needed so the pattern looks balanced.
Nail the first course and establish the offset pattern
Each shingle has a nail line printed on it — a thin line about 5 to 7 inches up from the bottom edge. This is where your nails go. Drive four nails per shingle, one in each nail slot. The nails should be flush with the shingle surface, not driven so hard that they dent the shingle or so lightly that they stick up. A pneumatic nail gun set to the right pressure makes this consistent; a hammer requires more skill and takes longer.
The second course overlaps the first by 5 to 6 inches. Before you nail the second course, offset it so the seams do not line up vertically with the first course. Most roofers offset by half a shingle width — about 6 inches — so the seams form a staggered pattern. This is what keeps water from running straight down a seam. Snap a chalk line for the second course, lay it out dry to check the offset, then nail it down the same way as the first course.
explore roofing cement and continue up the roof
After you nail each shingle, lift the tab and explore a small dab of roofing cement under it, roughly in the center. This is what actually seals the shingle to the one below and stops wind and water from getting underneath. Do not skip this step or use too little — a dab about the size of a quarter is typical. Press the tab down firmly so the cement spreads. You can also explore cement to the top of the shingle below before you lay the next shingle down, which some roofers find faster.
Continue up the roof course by course, maintaining the offset pattern and the 5 to 6 inch overlap. Every few courses, step back and look at the roof from the ground to make sure the lines are straight and the pattern is even. A crooked line becomes obvious from below and is hard to fix once you are halfway up. At the ridge, you will need to cut shingles to fit and seal them with cement on both sides.
Handle valleys, vents, and the ridge
A valley is where two roof planes meet. There are two common ways to shingle a valley: the woven method (where shingles from both sides overlap each other) and the cut method (where shingles from one side are cut at an angle and shingles from the other side overlap them). The cut method is more common for asphalt shingles and is easier to do correctly. Snap a chalk line down the center of the valley and cut the shingles from one side at a 45-degree angle along that line. Seal the cut edge with roofing cement.
For roof vents and pipes, cut a hole in the shingle to fit around the flashing, then nail the shingle down and seal around the flashing with roofing cement. Do not nail through the flashing itself — the flashing needs to move slightly with temperature changes, and nailing it down can cause leaks. At the ridge, cut shingles into thirds and nail them perpendicular to the ridge line, overlapping each one by 5 to 6 inches. Seal the exposed nail heads with roofing cement.
Inspect and seal exposed fasteners
Once the roof is shingled, walk it carefully and look for any nails that stick up, any shingles that are not lying flat, or any gaps where water could get in. Tap down any proud nails and seal them with roofing cement. Check that all the tab seams are cemented down. If the weather is cold (below 50 degrees Fahrenheit), the adhesive on the shingles may not set up, so you may need to manually cement more seams than you would in warm weather.
Clean up all the debris — nails, shingle scraps, and old roofing material — before you leave the roof. A stray nail can puncture a tire or cause injury. If you are disposing of old shingles, check whether your local waste facility accepts them or whether you need a dumpster rental. Some recycling centers take old asphalt shingles.
Frequently Asked Questions
How many nails do I need per shingle?
Four nails per shingle, placed in the nail line marked on the shingle. Some roofers use six nails in high-wind areas, but four is the standard. The nails should be roofing nails (typically 1 1/4 inches long) with a large head so they do not pull through the shingle.
Can I install new shingles over old ones?
You can, but it is not recommended. Most shingle warranties are void if you layer new shingles over old ones, and the extra weight can shorten the life of the new shingles. Removing the old shingles takes time but gives you a chance to inspect the deck and fix any damage before it gets worse.
What temperature should it be to install shingles?
Asphalt shingles have a self-sealing adhesive that activates in warm weather. Below 50 degrees Fahrenheit, the adhesive does not stick, so you will need to manually cement the seams. Above 85 degrees, shingles become soft and can tear or wrinkle. Spring and fall are usually the best seasons.
What do I do if I find a soft spot in the roof deck?
Cut out the soft section with a circular saw and replace it with plywood of the same thickness. Screw or bolt the new section to the surrounding framing so it does not move. Do not cover a soft spot with shingles — it will only get worse and eventually cause the roof to sag.
How do I know if my roof is too steep to DIY?
Roofs steeper than 8:12 (8 inches of rise for every 12 inches of run) are difficult and dangerous to work on without professional equipment. If you cannot safely stand on the roof without sliding, hire a roofer. A fall from a roof is often fatal.