Renovation 4th Edition
Page 23
right; otherwise, you’ll be reaching across your-
follow a standard nailing schedule of four nails per shingle or six nails for high-
self continually. Left-handers, of course, should
wind areas. trimmed-down shingles must have at least two nails. place the first and last
start right and work left.
nails in from the edges at least 1 in. all nails must be covered by the shingle above.
There are many ways to lay out and install
shingles. If you’re installing laminated shingles, a
pyramid pattern is best. With this method, you
precut a series of progressively shorter shingles,
based on some multiple of the offset dimension.
Nailing schedule: four nails per shingle is
standard; use six nails for high-wind areas. Because each successive course is, say, 5 in. or
Trimmed-down shingles must have at least
6 in. shorter, the stepped pattern looks like a
two nails. Place the first and last nails in
pyramid. Typically, pyramids start along a roof
from the edges at least 1 in. All nails must
be covered by the shingle above.
edge, with the first shingle in each course flush to
the rake starter strip.
Once the pyramid is established, the job goes
quickly. Just place a full shingle against each step
in the pyramid and keep going. Because the off-
set is established by those first shingles, you can
install full shingles until you reach the other end
of the roof. But most roofers prefer to work up
and out, maintaining the diagonal. If there are
color variations among bundles, they’ll be less
noticeable if the shingles are dispersed diagonally.
The frequency of a pyramid pattern’s repeat-
ing itself depends on how random you want shin-
gles to look. Traditionally, patterns repeat every
94
Chapter 5
Roofing jacks
Roofing jacks provide safe platforms on slopes. typically, install a pair of jacks
for every six to eight courses. to attach the jacks, level the pair by aligning the
jacks to horizontal chalklines, and drive two 10d galvanized common nails
through each jack into rafters. (jacks nailed only to sheathing are unsafe.) place
nails above the fastener line on the shingle because the nails will stay in place
after jacks are removed.
if you space each pair of jacks 8 ft. apart horizontally, they can be spanned
by 10-ft.-long planks that allow a 1-ft. overhang on each end. however, install
the two shingle courses above the jacks before you add the plank; otherwise, the
plank will prevent you from nailing those courses. to prevent a plank from sliding
out of a jack, nail through the hole in the front of the jack arm into the plank.
plank-and-jack removal is a two-person job, especially in windy weather.
above all, play it safe. first, move the plank to a secure location. to remove a
jack, sharply hammer its bottom upward, thereby driving the slotted jack holes
off the 10d nails. then, while being careful not to disturb the overlapping shin-
gles, slide the jack out. it’s a good idea to drive jack nail heads flush, but it’s not
imperative. to drive them flush, slide a flat bar under the overlapping shingle,
placing it atop the nail head, then strike the bar’s handle with a hammer. this
may require several blows.
fourth course, that is, every fourth course begins
with a full shingle. Whatever pattern you choose,
trimmed pyramid shingles should be at least 8 in.
Rake drip-edge
zzzzzz Laying out three-tab shingles
wide; otherwise, they’ll look flimsy.
36 in.
Keeping things aligned. As you work up the
30 in.
roof, align the tops of shingles to horizontal
chalklines. Chalklines wear off quickly, so don’t
snap them too far in advance; snapping
Vertical
chalklines each time you roll out a new course of
offset chalklines
building paper is about right. However, to get the
Horizontal
measuring done all at once, you can measure up
layout chalklines
from that original 12-in. line and use a builder’s
crayon to mark off exposure intervals along the
rake edges on both ends of the roof, and then
snap chalklines through those marks later.
Alternatively, if you snap chalklines only every
Cutouts
second, third, or fourth course, use the gauge on
the underside of your pneumatic nailer or on
Three-tab shingle
your shingle hatchet to set exposures for inter-
vening courses. If your shingling field is inter-
rupted by dormers, always measure down to that
original 12-in. line to reestablish exposure lines
above the obstruction.
Finally, if the ridge is out of parallel with the
3/4-in.
1-ft.-wide
3/4-in.
eaves by more than 3⁄4 in., stop shingling 3 ft. shy
overhang
tabs
overhang
of the ridge and start adjusting exposures so that
the final shingle course will be virtually parallel
Aligning three-tab shingle cutouts can be as easy as snapping two
with the ridge. For example, if there’s a discrep-
vertical chalklines 6 in. apart. Because individual shingle tabs are
ancy of 11⁄2 in., then at 3 ft. below the ridge, you’ll
1 ft. wide, a 6-in. offset wil line up shingle cutouts every other course.
Roofs
95
need to reduce exposures on the narrow end of
the roof by 1⁄4 in. in each of six courses.
Rake drip-edge
Underlayment
Valleys. Both open valleys (in which metal valley
zzzzzz using a pyramid pattern Layout
flashing is exposed) and closed valleys should be
Chalked
lined, as described in “Underlayment” on p. 82.
exposure lines
Closed valleys are more weathertight but slower
to install, so they’ve become less popular. Open
valleys are faster to install and better suited to
laminated shingles, which are too bulky and stiff
to interweave in a closed valley.
Once you’ve installed valley flashing, snap
Factory ends
chalklines along both sides to show where to trim
Control line 12 in.
above drip-edge
overlying shingles. Locate chalklines at least 3 in.
Starter strip
back from the center of the valley; oncoming
shingles cover valley flashing at least 6 in. When
nailing shingles, keep the nails back at least 6 in.
from the valley centerline—in other words, 3 in.
back from the shingle trim line—so nails can be
covered by shingles above. To seal shingle ends to
Fascia
board
the metal flashing, run a bead of roofing cement
Trim excess
and use on opposite
Starter strip
under the leading edge of each shingle, and put
rake edge.
dabs of cement between shingles. Ideally, you
Start with
full shingle.
should not nail through the metal at all, but that
could leave an inordinately wide area of shingles
Shingles overhang
unnailed. Besides, self-adhering waterproofing
drip-edge by 3/4 in.
membranes beneath the metal flashing will self-
seal around the nail shanks.
A pyramid pattern is best for installing laminated shingles that don’t have distinct
As a shingle from each course crosses a chalk-
cutouts. As you build the pyramid along the rake edge, trim excess from the rake end line, use a utility knife to notch the shingle top so a factory end always leads off each course. Align shingles to horizontal chalklines and bottom. Then flip the shingle over and, using you snap, not to lines printed on building paper.
a straightedge, score the back of the shingle from
P R O T I P
as shingles run diagonally into
an open valley, their leading
edges often end in sharp points,
under which water can run. to
prevent that, use a utility knife
with a hooked blade to remove
about 1 in. of the point, cutting
perpendicular to the bottom
edge of the shingle.
1. Carefully align the first shingle (which is uncut) to
the edges of both eaves and rake starter strips.
2. Shorten the second shingle in the
pyramid by the offset dimension. Use
the gauge stop on the bottom of the
pneumatic nailer to establish the
correct exposure between courses.
3. At this point, you could run courses all the way across
the roof, but most roofers prefer to work up and out,
maintaining the diagonal. Although this veteran roofer
didn’t need to snap horizontal chalklines across the roof
to keep courses straight, novices should.
96
Chapter 5
new Roofing over old
although placing new roofing over old may be allowed by some codes, “roofovers” tend
to be inferior. as noted earlier, you must strip a roof if there are two or more layers or if
existing shingles are curling.
Before beginning, replace or flash over old flashing as follows:
use aviation snips to cut away flashing around plumbing vents.
use a cold chisel to remove chimney counterflashing.
along the eaves, install a new drip-edge over the butt ends of existing shingles.
along the rakes, install a new j-channel drip-edge, which wraps around the old
rake flashing and starter courses.
Leave the old valley flashing in place, and install new over it.
This classic wood shingle roof has an open valley. Shingle
to level out an existing asphalt-shingle roof, rip down (reduce the height of) two
caps cover the roof hip.
courses of shingles, as shown in the drawing. Because asphalt shingles are routinely
exposed 5 in., rip down the first strip (the starter course) so that it is 5 in. high. then
notch to notch. Or, to speed installation, run
lay it over the original (old) first course so that the strip is flush against the butts of
shingles into the valley, and then when the roof
the original second course above. next, rip down a second strip (second course) 10 in.
section is complete, snap a chalkline along their
high, and put it flush against the butts of the original third course. you now have a
ends to indicate a cutline. To avoid cutting the
flat surface along the eaves. the third course of new shingles—and all subsequent
metal flashing underneath, put a piece of scrap
shingles—need not be cut down, just butted to an original course above and nailed
metal beneath shingle ends as you cut, using a
down. use 11⁄2-in. roofing nails for roofovers—or whatever length is necessary to reach
hooked blade in a utility knife or snips.
the sheathing.
Finally, codes in wet or snowy regions may
require that valleys grow wider at the bottom.
In that case, move the bottom of each
chalkline away from the valley center at a
rate of 1⁄8 in. per ft.
zzzzzz new shingles over old
New rake drip-edge
Old roofing
Third course
Second course
12 in.
Starter course
10 in.
5 in.
Closed-cut valleys are faster to install than woven ones
because you don’t need to weave shingles from two
New eaves drip-edge
converging roof planes at the same time.
When installing a new roof over an old one,
avoid a wavy-looking job by reducing the height of
the first two courses to establish a flat surface.
Roofs
97
P R O T I P
finishing the Ridge
ripper under the shingles and gently slicing
through the adhesive strips (see photo 1 on
Where composition shingles converge at the
p. 150). It’s best to do this when shingles are cool
if you mistakenly shoot a nail
ridge, they should be capped to keep out weather and the adhesive is somewhat brittle and easier
through a shingle, cover the nail
elements and create a neat, finished joint.
to break. If you attempt this when the roof is hot,
head with roofing cement or ure-
Traditionally, roofers created cap shingles from you’re more likely to tear the shingles. Actually
thane caulk and drive a new nail
leftover three-tab shingles, by extending the cut-
within 1 in.
working with the shingles—lifting them to
outs across the width of the shingle. Each stan-
remove nails or slide in new shingles—is best
dard shingle yielded three cap shingles, which
done when the shingle is warm and flexible.
the roofer gently folded to straddle the ridge and
To remove a damaged shingle, raise the shin-
cover the tops of oncoming shingles. Two roofing gles above and tear the old one out. If it doesn’t
nails per cap shingle are sufficient, with the nail
tear easily, use a utility knife to cut it out.
heads covered by successive shingles—until the
Remove the nails that held the damaged shingle
last cap shingle, which gets four nails. Two
by inserting a shingle ripper against the nail
important details: Cap shingles must be placed so shafts and prying up. Keep in mind that those
that prevailing winds blow over shingle overlaps,
nails are actually going through two shingle
rather than into them, which could lift and loosen courses—the one you’re trying to remove and the
them. And roofing nails must be long enough to
top of the course below. If you extricate the shin-
penetrate the several shingle layers at the ridge
gle and the nails don’t come up with a reasonable
and sink into the sheathing.
amount of trying, just knock the nails down with
These days, there are more options for cap-
your hammer and a flat bar.
ping the ridge, notably preformed ridge and hip
Fill old nail holes with roofing cement, and
shingles. These specialty shingles come prefolded slide the new shingle into place. Gently lift the
&n
bsp; and so are unlikely to split along the fold—a real
course above, and position nails so they’ll be
problem with laminated or luxury shingles,
overlapped by that course. Once you’ve inserted a
which are thicker and stiffer than three-tab vari-
new shingle, use the flat bar to help drive them
eties. Most composition shingle makers offer pre-
down, placing the flat bar atop the nail head and
formed ridge shingles to match the shingles you
striking the bar with a hammer.
use in the field. There also are plastic and metal
ridge caps, which, although clearly a different
material, can usually approximate the color of
Wood Shingles
field shingles.
There’s romance in wood shingles. Despite
Lastly, many modern roofs have vents along
wood’s tendency to cup, split, rot, grow moss,
the ridge, which allow air to rise and exit the
and catch fire, people still love it. Insurers, how-
house. In tandem with soffit vents, ridge vents
ever, don’t because it can catch fire and often
encourage a flow of air beneath the roof deck,
refuse to insure homes with wood roofs in fire-
helping to keep the attic cooler in summer and
prone areas. Keep in mind, too, that wood shin-
lessening the chance for ice dams in winter. To
gles take longer to install than asphalt shingles,
install a ridge vent, cut sheathing back at least
so labor will cost more. Regarding durability,
1 in. on either side of the ridge board as shown in Eastern white cedar and Western red cedar are
the bottom drawing on the facing page. Run
about the same—though each region’s noisier
underlayment and shingles to the edge of the
authorities assert that its shingles last longer. As
sheathing. Then nail the ridge vent over the open- white cedar shingles age, they turn silver; red
ing, straddling the shingles on both sides. In
cedar shingles turn dark brown to almost black.
most cases, the ridge vent is then covered by
cap shingles—with care taken not to block vent
pRepaRing the Roof
openings.
Be sure to read the earlier sections on sheathing,
underlayment, and flashing. And review the
asphaLt shingLe RepaiR
methods of asphalt-shingle installation, for they
Most roofs are repaired in response to leaks
have some things in common with wood shingling.
caused by a missing shingle or, more often, worn-