When attendees at the JLC Live expos see the schedule in front
of my demonstration clinic, they come up and ask, "Why would
anyone want to shingle a roof backwards?" While it may seem
counterintuitive, top-down roofing makes sense in a number of
situations. In the last couple of years, I've found myself
using it more frequently than shingling from the bottom up.
When I say top-down, I don't actually mean applying each course
of asphalt shingles in reverse direction starting at the ridge.
I do top-down roofing in lifts, or groups of courses, from 4 to
7 feet high, starting near the ridge.
In new construction, I choose top-down roofing in two
instances: when I'm concerned about scuffing up the shingles,
and on steep roofs when it's necessary to work from roof
staging. The technique also works well for reroofs (see
"Top-Down Great for Reroofs," below).
Top-Down Great for
My favorite time to use top-down shingling is on
strip and reroof jobs. I usually work with just my
brother, so there's no way we can strip and
reshingle even a ten-square section of roof in one
day. And with the local New England weather
forecasts averaging only 40% accuracy two days out,
I don't like the odds. I could strip and dry-in the
roof with tarpaper or cover it with a tarp, but
I've seen too many disasters.
Rather than strip the whole roof at once, I strip
horizontal sections, usually 8 to 12 feet wide,
starting at the ridge. I take a guess as to how
much we can accomplish in a day stripping and
reshingling and still have enough time to do a good
pickup of the debris before leaving. We then roll
out new underlayment and snap control lines. I
start the first course of new shingles so they
overlap the old shingles and work up from there. I
cap the ridge if the opposite roof is already
complete or just fold the top lap of the final
course over the ridge if it's not.
When I'm concerned about wind overnight, I lay a
horizontal 1x3 furring strip halfway across the
butt edge of the bottom course of shingles that are
only nailed up high. I drive screws every 3 feet
along the bottom of the furring so the screws
penetrate the old shingles, not the new ones. The
strip prevents wind uplift damage to this
No scuffing. Asphalt
shingles soften in the heat of summer and even on cool, sunny
days. Light traffic on softened shingles can scuff and bruise
the surface granules. While the damage may seem to be only
cosmetic, in fact the missing granules mean the shingles have
less protection and may wear out prematurely. With the top-down
approach, I don't have to walk on the new shingles, so scuffing
is not a problem.
Faster on steep pitches.
Top-down roofing actually saves me time on roofs with pitches
greater than 8, where I typically use roof jacks. All the jacks
and planks can be installed during the roof sheathing
operation. This makes handling and nailing off the sheathing go
faster. Plus, bundles of shingles can be spread out on the
staging planks — no need to attach cleats to hold the
shingles in place. I spread one bundle per sheathing panel for
three bundle-to-the-square shingles. A boom truck or shingle
conveyor makes short work of this task (see Figure 1).
Figure 1.After staging is in place, shingles are
boomed up and spread on the planks.
When shingling from the top down, the staging is removed as
you make your way down. This eliminates the need to scramble up
the roof over the freshly installed shingles to dismantle the
roof jack setups.
Prepping the Roof
The top-down process is pretty simple; you use the same layout
and installation techniques you would on a bottom-up job. In
the photos in this article, I'm using laminated (dimensional,
or architectural) shingles. Three-tab shingles require
additional vertical control lines (see "Layout for Three-Tab
Layout for Three-Tab
three-tab shingles, I use vertical control lines to
keep the cutout slots lined up. That also helps
prevent the slots from lining up in two successive
courses where a lower-shingle lift mates with the
completed section above.
I mark the vertical layout at the ridge and eaves,
measuring in the proper distance from a piece of
drip-edge tacked along the rake. The number of
vertical control lines you snap depends on the
shingle layout. For example, you'll need two lines
for the "racking" method and five or six lines for
the "pyramid," or "diagonal," method. I snap the
vertical lines between the ridge and eaves marks in
I use the same alternating colors for the
horizontal control lines. Though it may seem
excessive, you may want to consider snapping out
every course the first time you try top-down
shingling. If you do, you get a grid of
intersecting red and blue lines that makes keeping
track of the cutout slots automatic. Then you just
orient the upper corner of the first shingle in
each row with matching colored lines — blue
vertical and blue horizontal or red and red. Match
the top corner of the first shingle in the next
course with the opposite color, and you'll see as
you roof up the section that the top corner of each
starter shingle naturally matches the cross of
matching colored lines.
Once you get a feel for the alternating pattern of
horizontal and vertical control lines, you can
reduce the number of horizontal control lines on
the lower lifts of shingles. I usually snap the
same color horizontal lines every fourth course, or
20 inches. You could increase that to every sixth
course, or 30 inches. The key is to use one chalk
line color for every even numbered course and
another color for every odd line.
I begin by installing the eaves drip-edge and any
self-sticking eaves membrane needed at critical areas like the
eaves edge, wall-roof intersections, and valleys. I then set up
roof jack staging at comfortable levels up the face of the
roof, usually about 6 feet apart, with the top plank no more
than 5 feet from the ridge so I can comfortably cap the
Working off the top staging level, I roll out two courses of
tarpaper underlayment. I overlap the roof leg of the staging
jack with the first course of paper but keep the nails along
the bottom edge up 8 inches so I can slip the next lower course
of underlayment beneath it later. The second course overlaps
the first, as you'd expect, and can be nailed off completely
right up to the ridge. I then tack on the rake drip-edge over
With top-down roofing, it's especially important to mark
horizontal control lines so you end up with a standard 5-inch
exposure at the bottom. I determine the horizontal layout by
tacking a full shingle along the eaves, letting it overhang the
drip-edge the standard 1/2 to 3/4 inch. (You could just measure
from the drip-edge and make the adjustment for the shingle
height and overhang, but I tend to make math errors, so I like
laying out with an actual shingle.) Then, working from the top
plank and holding my tape measure against the top of the tacked
shingle, I mark down the roof along the rake in 5-inch
increments (5 3/8 inches for metric shingles), starting at the
ridge. I do the same at the opposite end of the roof, then snap
chalk lines between the marks (Figure 2). I don't snap every
course; lines at four- to six-course intervals (20 to 30
inches) are frequent enough to keep course drift in
Figure 2.Working from a carefully placed starter
shingle, a carpenter snaps control lines in 5-inch increments
starting from the top of the roof.
Starting a Lift
I pick one of the course lines to start shingling from, one
that leaves the shingle bottoms at least 6 inches above the
staging plank. Locating the nails on the first course of
shingles in each lift is critical. I drive two nails into the
top corners of each shingle to hold it in place. Nailing high
permits me to slide the top course of the next lift underneath.
At that point, I'll nail off the course properly.
I like to install all the shingles in the first course of each
lift before working up the roof (Figure 3). I find it easier to
keep straight where the nails of the first row go than to
switch nailing patterns and work multiple courses across at the
Figure 3.The first row of shingles in each lift
gets nailed in the top corners only so shingles from the lift
below can be slipped underneath later.
Once the first course is installed, I apply the rest as you
would field shingles in a regular bottom-up application (Figure
4). If the other side of the roof has been shingled, I install
the ridge cap shingles. Otherwise, I wait to do it from the
Figure 4.Once the lowest course in each lift is
installed, the rest of the shingles in that lift
At this point, I break down the top level of roof jack
Installing Additional Lifts
I install the next two courses of underlayment, then mark and
snap the next few horizontal control lines (Figure 5).
Figure 5.The roofing felt for each successive lift
easily slips beneath the last course above, which is not
stapled in the bottom 8 inches.
I repeat the procedure, temporarily fastening the first row of
the lift, then nailing off the successive courses until I reach
the bottom row of the shingles above (Figure 6).
Figure 6.The process repeats itself down the roof.
Control lines are snapped, and the bottom row gets nailed on
the top corners only.
Mating the last row of shingles to the lift above is the only
part of top-down roofing that's slower than bottom-up. I slide
each shingle of the last row beneath the bottom row of the
upper lift and nail it off while lifting up the shingles of the
row above — the ones that had been temporarily nailed
(Figure 7). I then lift the bottom edges of the next course of
shingles above that and properly nail off the temporarily
Figure 7.The next-to-last (left) and last (right)
rows of each lift slide under the bottom course above. Finally,
the bottom course gets permanently nailed off.
I usually nail each row separately, rather than moving across
the roof and working both rows together. That way, I'm sure I
haven't missed any shingles.
In cold weather, it can be difficult to lift the shingles
without overbending and cracking them. A roofing nailer helps,
since you don't have to lift the shingle very high in order to
sneak the nailer nose in place. Hand nailing is awkward.
In hot weather, the bottom of the first two courses of
shingles in each lift may seal to one another. One trick I've
used is to isolate the self-seal strip using a piece of the
release sheet from the eaves membrane, putting the siliconed
face in contact with the self-seal strip.
I haven't found a way to weave a valley using the top-down
shingle method. It's a bear to weave the last two courses when
a lower lift reaches the one above it. Instead, I first weave
the entire valley from the bottom up, installing just one
shingle to each side of the valley. The body of the roof can
then be shingled from the top down, working out from the valley
Cut valleys, on the other hand, are easy from the top down.
The shingles of the first roof plane you shingle will wrap
through the center of the valley and onto the opposite roof
plane. Before placing the shingle of the first row of each lift
through the valley, I lay a couple of loose shingles in the
valley beneath it. I press the shingle against the loose
shingles at the valley center and nail the top corners. The
loose shingles simulate the shingles I'll install later,
spacing the first shingle row off the roof surface just a
little. Without using the loose shingles as spacers, you're
likely to press the first row shingle too tight into the valley
crease, making it difficult to slip shingles beneath it
When I reach the valley shingle with the next lift, I sneak
the last shingle underneath, carefully lift the bottom, then
You can either shingle the opposite roof plane at the same
time as you work your way down the first plane or wait until
you've shingled the first plane down to the eaves edge. Either
way, it's easiest to cut and tar the valley edge before
breaking down the staging and starting each lower lift. Just
remember to nail the first row of shingles high and omit the
tar until after you've slipped the last shingle of the course
beneath into place.
Open metal-flashed valleys are straightforward. The only
caution I have is to skip the roof tar beneath the bottom
course of each lift until you complete the next lift
Mike Guertinis a builder and remodeler from East
Greenwich, R.I. He's the author ofRoofing With Asphalt Shingles(Taunton) and a member of the JLC Live
construction demonstration team.