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 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 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
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
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
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 protection kit (harness, rope and hook) only costs about $100 at home
- Wet roofs are slippery. Wear shoes with soft rubber soles for extra
- 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
- 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
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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
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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.
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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
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
Cover the roof with felt paper
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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.
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Photo 5: Don't skimp on staples
Place staples no more than 12 in. apart. Paper with too few staples will tear
out under your feet and could cause a fall.
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Photo 6: Overlap the ridge
Run the felt paper over the peak and overlap it onto the other side. Do the
same when you reach the peak from the other side of the roof.
Felt paper, also called tar paper or builder's
paper, helps shed water that gets under the shingles, protects the asphalt
shingles from the resins in the wood
decking, increases a roof's fire rating and
helps keep your house dry if it rains
during the job. Most roofing suppliers
carry 15-lb. and 30-lb. rolls of felt. For
most applications, 15-lb. felt works just
fine. Install 30-lb. felt if you plan to leave
the paper exposed for more than a
couple of days because it wrinkles less
then 15-lb. And 30-lb. felt doesn't tear as
easily, so it's safer to walk on when
you're working on steeper pitches.
Start a row by rolling out a short section
of paper and securing it with a
dozen staples grouped together near the
center of the paper (Photo 4). That way
you'll then be able to roll out a long section
and swing it back and forth until
your overlap is even. Each row of paper
should overlap the one below it at least 2
in. There will be overlap lines printed on
the paper to guide you. Overlap seams on
the same row 6 in.
Practice on a couple of 10-ft. sections
until you get the hang of it, and don't roll
out a 25-ft. section of paper on a steep
roof or when it's windy. If you're fastening
the paper with a staple hammer, try
to get a staple in every square foot of the
paper (Photo 5). That may seem like a lot,
but insufficiently stapled paper can tear
out under your feet, which could result
in a fall. Don't walk on any paper that
isn't completely stapled down. Fasten
the felt with cap staples/nails if you're
working on a windy day or are working on a roof with a pitch steeper than 6/12.
When you reach the top of the roof,
run your last row long (Photo 6), and
drape the paper over the peak (top ridge)
onto the other side. When you reach the
top on the other side of the roof, run that
paper up and over as well. That way
you'll end up with a watertight ridge.
Your local building official may want to
come out to inspect your roof at this
point, but sometimes you can get by with
snapping a few photos. Ask about the
inspection schedule when you pick up
Waterproof your valleys
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Photo 7: Flash the valleys
Install self-stick underlayment under the metal flashing. If you need more than
one flashing in your valley, lay them both in place and make sure they're straight
before nailing them down.
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Photo 8: Fold flashing over the peak
Cut the flashing back to the peak along each crease. Then fold the flashing
over the peak and cover the cut ends with self-stick underlayment.
Roof valleys channel a lot of water, so
they need extra protection. Start by
installing self-stick underlayment on the
decking. This process is much easier with
two people. Cut the underlayment to size
(or in sections for long valleys), and peel
off the entire plastic backer. With a
person on each end, fold the underlayment
in on itself, sticky side out. Then
lay it into the valley and unfold it. Try to
push it down into the crease of the valley
as tightly as possible. If this self-stick ice-and-
water underlayment bridges both
sides of the decking, leaving a gap underneath,
it could tear once you install the
metal valley flashing. Run the underlayment
past the drip edge at the eaves, and
trim off the extra with a utility knife.
Once it's smooth, nail it down on the outside
Finish installing felt paper on the rest
of the roof, overlapping the self-stick
underlayment. Be careful when you trim
back the felt paper so you don't slice into
the underlayment. Photo 7 shows the
underlayment covering the felt on one edge a couple of inches. This will keep
water farther away from the inside
corner of the fascia. You can extend the
center out even more but not so far that
water overshoots your gutters if you have
Be careful not to nail your shingles any
closer than 8 in. from the center of the
valley. Once all the shingles are installed,
snap lines as guides to trim them off.
There should be 6 in. of the valley
exposed on top (3 in. on each side), and
each side of the valley should widen 1/8
in. for every linear foot of the valley run.
So, if you have a valley run of 16 ft., your
valley exposure would be 6 in. on the top
and 10 in. on the bottom.
Another way of dealing with valleys is
to use the “weave” method, which we
don't cover in this story. The shingles are
woven together from both sides of the
valley. The benefit of a woven valley is
that it doesn't leave an exposed flashing,
which results in a cleaner look. The
downfall is that leaves and twigs don't
get washed away as easily, which can
cause little water dams. This is especially
true for roofs with low pitches.
Avoid Extreme Temperatures
Avoid roofing your house in below-freezing
temperatures. The shingles
won't stick together, which makes them
prone to wind damage. A couple of cold
days won't cause trouble, but after
weeks and months, the adhesive strips
on the shingles can attract dust and fail
to seal even when the weather does
warm up. And try to avoid working on
sunny days when the temperature is
above 90 degrees. The ice-and-water
underlayment gets overly sticky and
difficult to work with, and the shingles
get soft and are easily scuffed by feet
Begin with starter shingles
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Photo 9: Install starter shingles
Run the row of starter shingles 1/2 in. past the drip edge. Position them so
the adhesive strip is toward the bottom and facing up. Place nails 2 to 3 in. up
from the bottom of the eave.
Water can get in the seams between any
two shingles, but that's OK because shingles
overlap and the seams are staggered.
But if you don't use starter shingles, water
will run in between the seams on the first
row and right onto the underlayment,
increasing the odds of a leak. The starter
row shingles are only half as wide as a full
shingle. If they were full size, the top half
of the first row would have three layers of
shingles instead of the two the rest of the
roof has, causing a visible hump.
Don't bother snapping lines for the
starter shingles; just overlap them 3/4 in.
past the drip edge. Fasten them down
with five nails about 2 to 3 in. up from
the bottom of the eave. Position the
starter shingles so the adhesive strip is
toward the bottom and facing up (Photo
9). The adhesive strip bonds to the shingle
above it, creating a nice tight seal,
reducing the chance of wind damage and
Some pro roofers install starter shingles
on the gable ends as well. It's not
usually required, but it provides a cleaner
look. Hang gable-end starter shingles 1/2
in. past the rip edge, and make sure you
overlap the starter shingle on the eave by
2 to 3 in.
Rent or Buy?
Unless your roof is tiny, you're going to
want to get your hands on a pneumatic
roofing nailer. Prices range from $100 to
$300. Renting one costs about $35 a
day or $90 a week, so if you own a compressor,
you might as well buy rather
than rent. A compressor rents for about
the same as the nailer. If you don't own
a compressor and know you're going to
finish your house in less than a week,
then renting is probably the way to go.
If you do buy a roofing nailer and you
know you'll only use it for one job, a
cheaper model will work just fine. It just
won't be as durable as the high-end
models the pros use. But don't tell
anyone you bought it. If the word
spreads that you're a roofing gun owner,
you run the risk of being recruited by a
whole bunch of friends and neighbors to
help work on their roofs.
Install the shingles
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Photo 10: Nail on shingles
nailing instructions is
nailing is the biggest
cause of roof failures
in storms. Where
and how often you
nail your shingles will
depend on wind
speeds in your area
and the pitch of your
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Photo 11: Run shingles long, then trim them off
For nice straight lines, run shingles over the edge of
the roof. Then snap a chalk line and trim them off with a
hook blade in your utility knife. If the overhang is more than a
foot, cut some off and use the remainder elsewhere.
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Hook blades are used for cutting shingles. They fit into any standard utility knife just like straight blades.
Laying shingles isn't easy, but it's probably
the simplest part of roofing a house. Line
up the bottom of the first row of shingles
with the bottom edge of the starter row,
making sure the seams are staggered.
With that row complete, you'll need to
figure out the reveal (the portion of the
shingle that isn't covered by the one
above it). Standard reveals vary between 5
and 6-1/2 in. Whatever the reveal is supposed
to be, snap a horizontal line that
distance from the top of the first row of
shingles (see Figure A, above).
Your roofing gun should have an
adjustable guide to help keep the rows
straight. If it doesn't, cut a block of wood
the same size as your reveal and use that
as a gauge. Slightly wavy rows won't be
noticeable from the ground, so only snap
lines every several rows to straighten
things out. It's easier to work from right
to left if you're right-handed. Stagger
each row so the seams don't line up.
Follow the stagger pattern recommended
by the manufacturer of your shingles.
Use partial shingles to start subsequent
No one will notice if the last rows are
not the same size on both sides of the
ridge, but it can be very noticeable if the
row that meets the ridge has a 4-in.
reveal on one side and a 1-in. reveal on
the other. Once you get within 8 ft. of the
ridge, measure down to your shingles at
each end of the row. If one side is closer
to the peak than the other, snap lines for
all the remaining rows, making the
reveal on one side progressively larger
until you make up the difference. Don't
adjust any row by more than 3/16 in.
Every shingle brand has its own nailing
pattern requirement. The pitch of
your roof and the wind conditions in
your area also affect how many nails to
use and where. Most shingles require
four to six nails, about 1 in. in from each
side and placed so they get covered at
least 1 in. by the shingle above them. The
nails should penetrate the decking at
least 3/4 in. Most pros use 1-1/4-in. zinc-coated
Nail straight into the shingle, and
adjust the setting on your gun or the
pressure on your compressor so the nails
pull the shingle tight to the decking but
stay flush with the surface. Keep a
hammer close at hand to take care of
nails that get only partially driven in.
And never use staples! Even if a buddy has an old roofing stapler with free staples,
politely decline. Staples don't have
the holding power of nails; they tend to
rust out before the shingles go bad; and
most manufacturers don't allow staples,
so you'll void the warranty.
When you reach the ridge, use the
same technique as you did with the felt
paper: Wrap the first side over the top,
and then wrap the second side over the
first. Cut the shingles to size with a utility
knife fitted with hook blades. Run the
shingles long over hip ridges and rakes,
and in the valleys. When you're all done
installing the shingles, snap lines and
trim the shingles to the line (Photo 11).
Architectural vs. Three-Tab Shingles
The shingles shown here are commonly called “architectural.” Some architectural shingles are partially laminated (two layers), and others are fully laminated, which gives
them more of a textured look, similar to wood shakes. Because of the extra material,
architectural shingles are heavier. Some can handle winds up to 150 mph, which is
twice the wind rating of many three-tab shingles.
Architectural shingles are easier to install because you don't have to worry about
lining up the tabs vertically. The life span depends on the quality of the shingle. Both
styles are available with 25-year and 30-year warranties. Expect to pay about 15 to 20
percent more for standard architectural shingles than for standard three-tabs.
Whichever you choose, make sure all the bundles have the same “lot” number on
the packaging. That means they were all made in the same batch or run. Shingle color
can vary noticeably from one batch to another.
Install step and dormer flashing
It's possible to reuse existing step flashing
and dormer flashing, but the best
way to get a watertight seal is to tear off
the siding in those areas and install new
flashing. Start by running self-stick
underlayment at least 6 in. up onto the
walls. This provides an additional barrier
if water does get past the flashing. Cover
the front wall first and then work your
way up the side wall. Overlap the sidewall
underlayment around the corner
onto the front wall about 1 in. or so.
Install the shingles right up to the
front wall. Cut a couple of inches off the
vertical portion of the dormer flashing,
and run the horizontal portion past the
side wall that same distance. Nail the
dormer flashing to both the wall and the
Make a 1- to 2-in. cut with a tin snips
at the bend in the first step flashing. Run
a bead of sealant on the corner edge of
the dormer flashing, and then run that
step flashing past the dormer flashing
the same distance you made your cut.
Bend the step flashing around the corner
onto the dormer flashing with your
Install your next row of shingles over
that first step flashing, then cover that
row with a step flashing, and so on. Nail
the step flashing to the wall toward the
top of the flashing at the end that's closer to the peak, so the next step flashing
in line will cover the nail. Don't nail
them down through the shingles. For
information about flashing around chimneys,
see Installing Chimney Flashing.
Figure B: Step and dormer flashing
Figure B: Step and Dormer Flashing
Weave the step flashing and the roof shingles together so that water can't get under the shingles. Pay careful attention to the corner details.
Working around vents and stacks
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Photo 12: Make plumbing vents leakproof
Install a layer of underlayment around vent pipes and caulk with roof
sealant before shingling. Run shingles halfway past vents before installing vent
2 of 4
Photo 13: Add the vent flashing
Drive three nails along the top edge of the flashing and one at each of
the lower corners.
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Photo 14: Shingle over the vent flashing
Seal the nail heads, and trim around the stack flashing with a utility knife fitted with hook blades.
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Photo 15: Add ventilation
If you need more ventilation, cut additional vent holes in the decking with
a circular saw and install vent flashing.
Installing shingles around attic vents,
plumbing vent stacks and furnace stacks
is basically the same process. The main
difference is that you'll install a piece of
self-stick underlayment around all the
stacks, but you just need to roll the felt
paper over the vent holes and cut out the
holes. When installing the felt paper over
a stack, it's OK to make an oversize hole.
But before you roll out the row of paper
above the stack, cut a 2- or 3-ft. section of
self-stick underlayment, cut a hole in it slightly smaller than the diameter of the
stack, and slide it over the stack. Make
sure the piece is large enough so that the
next row of felt paper overlaps the top at
least a couple of inches (Photo 12). Caulk
around the pipe when you're done.
Install the shingles up and halfway
past the vent hole or stack. Next, install
your vent or stack flashing over that row
of shingles (Photo 13). Nail it down with
your roofing gun, top and bottom.
Seal the top nail holes and continue on
up with your shingles. Trim the shingles
with your utility knife (Photo 14). Some
vent and stack flashing is covered in protective
plastic, which will have to be
If you're installing the type of stack
flashing with a rubber boot that seals
around the pipe, spray-paint the pipe a
similar color as your roof. You can also paint electrical masts and other projections
(before installing shingles). This
simple step adds a lot to the finished
look of your roof.
To find out if you have proper attic
ventilation, search attic ventilation calculator (GAF has one version). Just type in the dimensions of your attic to learn how many vents you need. If you don't have adequate ventilation, cut in more holes with a circular saw (Photo 15).
Cap the ridge
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Photo 16: Cap the ridge
Snap chalk lines to help keep the row of ridge cap shingles straight. Install
the ridge cap so the prevailing winds blow over the overlap seams, not into them.
Once all your shingles are installed,
you'll need to cover (cap) the ridge (and
hip ridges if you have a hip roof). The top
ridge cap shingles will overlap the hip
ridge cap, so start with the hips. Snap a
couple of guide lines just a little inside
the perimeter of the ridge so the lines get
covered up when you're done. Nail each
shingle on both sides about 1 in. above
the overlap seam (Photo 16). Store-bought
architectural-style ridge caps are
often two layers thick, to match the look
of the shingles. You may need longer
nails to fasten the ridge because of all
the extra layers of shingles.
Install the top ridge cap so the prevailing
winds blow over the overlaps rather
than into them. If wind isn't an issue,
start at either side, or start at both sides
and end in the middle. Rip the top half
off the last ridge cap shingle, and nail
through the face of it with two nails on
the ends of each side.
Seal it up
Before you put your ladder away, sweep
all the debris off the roof, and then seal
all the exposed nails on your vents and
stack flashing. If you used stack flashing
that has the rubber boot, seal the area
where rubber meets the pipe. Avoid silicone
(it won't hold up) and asphalt-based
sealants (they tend to dry out when
exposed to direct sunlight). Our roofers
prefer a product called Lexel
available through our affiliation with Amazon.com. It's clear like silicone, sticky as model glue and lasts for years. And remember, these areas you sealed require maintenance—they should be inspected every few years.