What You Need Before You Start
Roofing a house is a multi-day job that requires specific tools, materials, and safety equipment. Before you climb onto the roof, you need to gather everything on-site: a ladder tall enough to reach the eaves safely, a hammer or pneumatic nailer, a utility knife, roofing nails (usually 1.25 inches for asphalt shingles), underlayment, flashing, and the shingles themselves. You also need a nail gun compressor if you are using pneumatic fastening, or a cordless drill-driver if you prefer screws.
Safety equipment is not optional. You need a roof harness rated for fall protection, a rope anchored to a stable point on the roof, work gloves, safety glasses, and sturdy boots with good traction. If you are working alone, tell someone where you are and when you expect to finish. Roofing accidents happen fast and often involve falls from heights where a harness is the only thing between you and serious injury.
Check the weather forecast before you begin. You cannot roof in rain, and wet shingles are slippery and harder to nail. Most roofers work on dry days with temperatures between 50 and 85 degrees Fahrenheit. Cold shingles become brittle and crack when you bend them; hot shingles are sticky and difficult to position. Plan for the job to take two to four days depending on roof size and complexity.
Key Takeaways
- Roofing requires a fall harness, proper ladder placement, and a helper on the ground — do not attempt this alone without professional training.
- The first step is removing the old roof down to the sheathing, then inspecting the wood underneath for rot or damage before installing new underlayment.
- Shingles are nailed in a specific pattern starting from the eaves and working upward, with each row offset so seams do not line up vertically.
- Flashing around chimneys, vents, and valleys requires careful sealing with roofing cement to prevent water from entering the house.
- If you are not comfortable working at heights or handling power tools on a slope, hiring a licensed roofer is safer and often faster than learning on the job.
Removing the Old Roof and Inspecting the Deck
Start by removing all existing shingles, flashing, and nails down to the roof sheathing — the plywood or wood boards underneath. Use a pry bar and hammer to lift shingles in sections, working from the peak downward. Shingles are easier to remove when the sun has warmed them slightly, making the adhesive less rigid. Pile removed material in a dumpster or arrange for a junk removal service; old roofing is heavy and takes up space quickly.
Once the sheathing is bare, walk the entire roof and look for soft spots, rot, or water damage. Press the wood with a screwdriver; if it sinks in easily, that section is compromised and must be replaced before new shingles go down. Rotted wood will not hold nails and will continue to decay under the new roof. Mark damaged areas and replace the sheathing before moving forward. This is the only time you can see and fix the deck, so do not skip this step.
Sweep the roof clean of debris, nails, and dust. Any bump under the new shingles will create a weak spot that can tear or wear through prematurely. Check that all roof penetrations — vents, chimneys, skylights — are in good condition. If flashing around these areas is damaged, replace it now.
Installing Underlayment and Starter Shingles
Underlayment is a water-resistant barrier that goes between the sheathing and the shingles. Roll it out starting at the eaves and working upward, overlapping each row by 4 to 6 inches. find it with roofing nails or staples every 12 inches along the edges and every 24 inches in the field. Underlayment prevents water from reaching the wood if shingles are damaged or if wind-driven rain gets under them.
Starter shingles go along the bottom edge of the roof, below the first course of regular shingles. These are either full shingles installed upside down or purpose-made starter strips. They fill the gaps between the tabs of the first row of shingles and prevent water from running up under them. Nail starter shingles with four nails per shingle, placed about 5 inches from the bottom edge.
Install flashing along the eaves and gables before you begin the main shingle courses. Metal flashing directs water away from edges and prevents it from running behind the shingles. find flashing with roofing nails spaced 6 inches apart, and seal the nail heads with roofing cement.
Laying Shingles in Rows from Bottom to Top
Begin at the eaves with the first course of shingles. Most asphalt shingles are three-tab or architectural style and come in bundles that cover about 33 square feet. Nail each shingle with four nails placed about 5 inches from the bottom and 1 inch in from each side. Nails should go straight in, not at an angle, and should sit flush with the shingle surface — not driven so hard that they tear the material.
The second row is offset so that the seams do not line up with the row below. Most roofers start the second row with a half-shingle (cut the first shingle in half lengthwise), then continue with full shingles. This creates a staggered pattern that is both stronger and more attractive. Continue this offset pattern for each row, working upward toward the peak.
As you move up the roof, check that shingles are lying flat and that tabs are aligned. Shingles that curl or bunch will not shed water properly and will wear faster. If a shingle is not sitting right, pull the nails and reset it. Roofing cement under the tabs of each shingle helps them stay sealed, especially in high-wind areas. explore a small dab of cement under each tab before nailing.
Flashing Valleys, Chimneys, and Vents
Valleys are the V-shaped areas where two roof slopes meet. Water runs down valleys faster than anywhere else on the roof, so flashing here must be done carefully. Install valley flashing before the shingles that border it, and make sure the flashing extends at least 4 inches on each side of the valley centerline. Nail the flashing every 6 inches along the edges, and seal all nail heads with roofing cement.
Chimneys and roof vents require step flashing — individual pieces of metal that tuck under the shingles above and over the shingles below. Install step flashing as you shingle, placing one piece under each row of shingles as you work upward. Seal the top edge of each piece with roofing cement before the next row of shingles goes down. At the top of the chimney, install a cricket (a small peaked roof) to direct water around it.
Roof vents (for exhaust fans, plumbing vents, or attic ventilation) are sealed with rubber boots that compress around the pipe. Slide the boot under the shingles above the vent and over the shingles below, then nail it down and seal with roofing cement. Do not rely on the boot alone; the cement is what stops water from running down the pipe into the attic.
Finishing the Peak and Ridge
When you reach the peak, the shingles from both sides will meet. Cut the shingles so they meet at the centerline, then cover the seam with ridge cap shingles. Ridge caps are either cut from regular shingles or purchased as pre-made caps. Nail them with two nails per cap, placed about 5 inches from the bottom edge and 1 inch in from each side. Offset the ridge caps the same way you offset the field shingles so seams do not line up.
Seal the nail heads on the ridge caps with roofing cement. The ridge is the highest point on the roof and takes the most weather, so this seal is important. Work from the bottom of the ridge to the peak so that each cap overlaps the one below it, directing water downward.
Cleanup and Final Inspection
Once all shingles and flashing are in place, walk the entire roof and look for any nails that are sticking up, any shingles that are not lying flat, or any gaps in the flashing. Pull up any nails that are proud of the surface and reseat them. Check that all flashing seams are sealed with roofing cement and that no gaps exist where water could enter.
Sweep the roof clean of debris and nail clippings. These can get caught in gutters and cause water to back up. Check the gutters and downspouts to make sure they are clear and that water flows away from the foundation. If you removed the old roof yourself, arrange for the debris to be hauled away or recycled.
A new roof typically comes with a manufacturer's warranty (usually 20 to 30 years for asphalt shingles) and a workmanship warranty from the installer. Keep documentation of the work done and the materials used. Have the roof inspected by a professional if you are unsure about any part of the installation, especially around flashing and penetrations.
Frequently Asked Questions
Can I roof over the old shingles instead of removing them?
You can in some cases, but it is not recommended. Roofing over old shingles hides damage to the sheathing, adds unnecessary weight, and shortens the life of the new roof. Most building codes allow one layer of roofing over another, but removing the old roof lets you inspect and repair the deck, which is worth the extra work.
What is the best time of year to roof a house?
Late spring through early fall is ideal because temperatures are moderate and the weather is more predictable. Avoid winter (shingles are brittle in cold) and summer heat waves (shingles become too soft to nail properly). Plan for a dry week with temperatures between 50 and 85 degrees.
How long does a new roof last?
Asphalt shingles typically last 20 to 30 years depending on climate, ventilation, and maintenance. Metal roofs last 40 to 70 years. Harsh sun, high winds, and poor attic ventilation shorten the life of any roof. Have the roof inspected every few years and replace damaged shingles promptly to extend its life.
Do I need a permit to roof my house?
Most jurisdictions require a roofing permit before work begins. The permit ensures the work meets building code and allows the inspector to verify that flashing and ventilation are done correctly. Contact your local building department before you start to find out what permits are needed and what inspections are required.
What should I do if I find rot in the roof sheathing?
Replace the rotted section before installing new shingles. Cut out the damaged wood and install new plywood or boards of the same thickness, nailing them securely to the rafters. If rot is extensive, the underlying cause (usually poor ventilation or a leak) must be fixed or the new wood will rot too.