Can you do it yourself?
Make no bones about it—roofing is hard work. There’s no hiding from the elements. You can’t be afraid of heights and you need to be pretty fit. Before committing to this how to roof a house project, try this: Get out a ladder and climb up onto your roof. If you can’t walk around on it comfortably, hire a pro. If you passed this first test, go to the lumberyard or home center and throw a bundle of shingles onto your shoulder. Imagine yourself carrying that load up a ladder…many, many times.
If you’re still feeling positive about this how to roof a house at this point, why not give it a shot? You can skip a lot of heavy lifting by having your roofing supplier hoist the shingles onto the roof. Be sure you spread the load evenly across the length of the roof’s peak. However, don’t have the shingles delivered to the roof if you have two layers of old shingles yet to tear off—it could be too much weight for your trusses.
After you’ve obtained a permit (if needed) and safely stripped the roof clean, nail drip edge flashing flush along the eave.
Windblown heavy rain and/or snow can force water up and under even properly installed shingles. Even worse are ice dams (frozen water/snow that builds up on roof edges), which can wreak havoc by allowing water to seep up under lower shingles and then drip into your house. To guard against such seepage, apply self-adhesive waterproof underlayment (“ice barrier”), which adheres tightly to bare roof sheathing and seals around nails driven through it. Buy it at roofing supply companies or home centers. In severe climate regions, most building codes require applying it 3 to 6 ft. up from the eave (minimum of 2 ft. past the exterior wall). Call your building inspector for local details.
Cover the rest of the roof with No. 15 asphalt-saturated felt underlayment (some codes may require No. 30). Each layer overlaps the lower one by at least 2 in. Follow this step by nailing drip edge along rakes (sides of roof), on top of the underlayment. As you did with the flashing, always lap upper pieces over lower pieces. The felt keeps the roof deck dry before shingles go on, protects against wind-driven rain as shingles fail and increases fire resistance.
Next, find the center of the roof at the top and the eave, then snap a vertical chalk line. Most pros use this line to begin shingling, working left and right toward the rakes. Shingle manufacturers may recommend starting at the left rake edge, so check package recommendations.
For the first row of shingles, called a starter course or strip, you cut the tabs off three-tab shingles and apply them with the self-sealing adhesive strip facing up along the eave. Make sure this row has a slight overhang (1/4 to 3/8 in.) beyond the drip edge. The starter course protects the roof by filling in the spaces under the cutouts and joints of the next row (first course) of shingles. The adhesive on the starter course seals the tabs of the first full course.
Finally, nail the first course of shingles directly on top of and flush with the starter course. Use four roofing nails per shingle, as indicated on package instructions (six nails in high-wind areas). Once this course is laid, you can begin snapping horizontal chalk lines up the roof to ensure straight rows. Make sure to expose 5 in. of the shingle tabs where the bottom edge of the tab meets the top of the cutout.
Tear off the old
It’s impossible to properly install new flashing and underlayment if you don’t tear off the old roof beforehand. When tearing off the existing shingles, be sure to remove all the old nails or pound them flat. Protruding nails will tear holes in your new shingles. If you have movable items near your house and you’re worried they might get damaged, relocate them. Invest in a few large tarps to protect your plants and landscaping and to catch the thousands of nails that will rain down off the roof. It can be downright impossible to remove old self-stick ice-and-water underlayment, but it’s OK if you have to leave it in place. And if at all possible, have the rented trash bin parked close to the house so you can toss in the old shingles right from the roof. For more information, see How to Tear Off Roof Shingles.
Figure A: Roofing Overview
This cutaway drawing shows the steps involved in roofing a house.
Install the drip edge
Metal drip edge isn’t usually required (check with a local building official), but it gives roof edges a nice finished look, prevents shingles from curling over the edge, and keeps water from running directly down your fascia boards.
Before you install the underlayment, fasten the drip edge that covers the fascia on the eaves. The whole length of the fascia is probably not perfectly straight, so don’t snap a line; just hold the drip edge snug against the fascia and fasten it through the top into the decking with roofing nails. Nail it every couple of feet.
Install the drip edge on the gable ends of the roof after you finish installing your underlayment. Start at the bottom side of the gable, and overlap the sections of drip edge a few inches as you work your way up the roof (see Figure A). Use a tin snips to cut the drip edge to size.
When it comes to roofs, even the best safety equipment is no substitute for common sense and good judgment. Here are some tips for working safely on a roof:
- Leave steep and/or high roof work to the pros. No amount of money you could save is worth the risk of death or a lifelong disability from a fall.
- A fall protection kit (harness, rope and hook) only costs about $100 at home centers.
- Wet roofs are slippery. Wear shoes with soft rubber soles for extra traction.
- Keep the roof swept clean of dirt and debris.
- Everyone on the ground should wear a hard hat—even the most careful worker can drop a tool off the roof.
- Always look and call out before tossing anything down.
- Carefully position ropes and extension cords so they’re not underfoot.
- Check the weight rating on your ladder—it needs to hold you plus 80 lbs.
- Extend the top of the ladder at least 3 ft. above the roof edge so you’ll have something to hang on to as you step onto and off the roof.
- Never step on any of the ladder rungs above the roof.
- Set up scaffolding to install the drip edge and first few courses.
Roll out the self-stick underlayment
Photo 1: Stick on the underlayment
Protect the roof against ice dams and windblown rain with self-stick ice-and-water underlayment. Peel off the top half of the plastic backing as you unroll the underlayment.
Photo 2: Peel off the bottom backing
Make sure the underlayment lies smooth before you nail the top edge. Then pull off the lower half of the backing.
Stick the bottom part of the underlayment to the roof of the house.
Install the second course just like the first, using the guidelines on the underlayment to get the correct overlap.
When an ice dam forms on a roof (usually caused by poor attic insulation/ ventilation), ice and water can work their way up under the shingles and leak back into the house. Also, strong winds can blow rainwater under shingles. Self-stick roofing underlayment (often called “ice-and- water” underlayment) can prevent this because it sticks to the roof decking to seal out water. It also seals around nails, which keeps water from leaking through nail holes.
Rolls of self-stick underlayment have a plastic backing so the material won’t stick to itself. The backing is separated down the middle. Line up the lower edge of the roll with the outside of the drip edge. Peel back part of the uppermost backing on the roll, and nail the top corner of the underlayment to the decking. Start pulling the roll across the decking using the backing, making sure the material is lying as flat and as straight as possible as you pull.
You’ll be able to roll out long sections at a time if you have a low-pitched roof, but the underlayment may slip off the eaves on steeper roofs, so roll out no more than 10 ft. there (Photo 1). It’s important to make sure all your underlayment lies flat before you fasten it to the decking. Ripples and lumps can telegraph through the shingles and may be noticeable from the ground.
On warm days, self-stick underlayment will stick to clean decking without any fasteners. Fasten it to the roof with staples or nails on colder days, but only fasten the top part of the underlayment until you go back and peel off the bottom half of the plastic backing (Photo 2). The higher the temperature outside, the stickier the adhesive on the rolls gets. This ice-and-water underlayment is tricky to work with on super-hot days; keep that in mind when you plan your project.
Many severe climate areas require self-stick underlayment to be installed at least 2 ft. in from exterior walls. This means you’ll need two rows if you have 2-ft. eaves. Any two sections of underlayment on the same row should overlap a minimum of 6 in., and each course should cover at least 2 in. of the one below it (Photo 3). These rules can vary, so always consult your local building official.
Cover the roof with felt paper
Photo 4: Roll on the felt paper
Cover the roof above the underlayment with roofing felt paper. To start each course, drive a dozen staples grouped close together. Then unroll the felt and straighten out the row before you add more staples.