A New Way to Install Slate Roofs - Continued
Along the gable ends, we'll use a 1x4 or 1x6 instead of
strapping, to give us good nailing in the fly rafter and to get
us out over the rake trim. We then nail a rough-cut, full
1-inch-thick 1x4 on top at the outer edge, bringing the height
up flush with the battens that we install on the rest of the
roof. A copper L-flashing covers the top of the trim (Figure
Figure 5.Before slate is installed, copper rake
flashings get nailed into the strapping that runs along the
Laying out and installing the battens is probably the most
critical step in a Nu-lok roof. Do this right and the rest of
the job will go smoothly.
The battens get installed at 12 1/8 inches on-center (Figure
6). We use a layout stick — a piece of strapping or
plywood drilled with holes every 12 1/8 inches — and
hand-drive a series of 4d or 6d finish nails up every other
piece of strapping to mark the layout lines (we just leave
these in place, since they're well below the level of the
slate). We drill the first hole at the bottom of the layout
stick 131/4 inches from the end. Holding this at the outside
edge of the fascia trim gives us a preset overhang of a couple
of inches. This may vary from job to job, depending on the
building's eaves details, but what's important is that the
battens are spaced regularly at 121/8 inches up the roof.
Figure 6.The metal battens are installed at 121/8
inches on-center. To speed layout, the author's crew uses
layout sticks drilled with holes, then drives small finish
nails at every batten location. When final chalk lines are
snapped from end to end of the roof, the nails serve as a
cross-check that the overall layout is square and parallel to
We snap lines most every course up the roof; I'd recommend
snapping every line for your first job, until you're accustomed
to the system. We take some extra time to make sure the initial
layout lines are parallel to the eaves and square to the rake
trim. If this layout is good, the rest of the roof falls into
We'll check the distance to the ridge to make sure we don't get
left with an ugly narrow strip at the top. It's possible to
fudge the courses slightly tighter by trimming the top end of
the link channels. We'll do this for the top few courses if
necessary to maintain a nice reveal at the cap.
We nail down the battens with 8d galvanized ring shanks,
shooting right through the 18-gauge metal. The battens come in
12-foot 6-inch lengths. If we need to cut them, we've found
that a Morse Metal Devil blade in a cordless circ saw works
well; it doesn't spark or even heat up the steel the way a
Getting Down to Slate
After loading the roof, installing the slate is the easy part.
We typically start at the ridge and install a couple of courses
there, then work outward from any valleys and hips, filling in
the flat field of the roof last.
Ridge. We nail full-dimension
rough-cut 1x4s along the ridge on top of the strapping (Figure
7), which comes flush with the battens and gives us nailing for
the ridge flashing and cap slates. We use 8-foot sections of
flashing, usually 24-gauge galvanized, since it's concealed. We
nail the cap slates through the flashing, then seal the holes
with clear Lexel. You could also step-flash the ridge.
Rough-cut 1x4s nailed on top of the
strapping at the ridge serve as backers for the ridge flashing
and cap slates. The author uses Lexel sealant to seal the nail
Because the cap slates are rigidly fixed, we shorten the last
course of slates by about 1/4 inch so they'll slide in and out
a little easier (in case we need to make an adjustment, or
someone ever needs to make a repair).
Valleys. We use full-size
16-by-16-inch slates at the valleys, cutting them so as to get
as much coverage as possible (Figure 8). This eliminates small
triangular pieces, which clutter up the valley and would be
tricky to support. Every slate needs to have a horizontal
bottom edge that rests in the clips. While the field slates
usually get support from two link channels, valley slates are
often supported by only a single clip on one side; the valley
side nests in the valley and is held down by the course
Figure 8.Using full-size 16-by-16-inch slates for
the valleys gives maximum coverage without a lot of small
We also weave in 24-gauge galvanized steel counter flashings up
the valley (Figure 9). We bend these on the ground to match the
valley angle, then angle them with aviation snips on the roof
to follow the bottom edge of the slates on each side of the
valley. The flashings rest in the clips along with the slates.
We also squirt a bead of Lexel between the slate and the metal
for good measure.
9.Galvanized steel counter
flashings supported by the slate clips supply extra water
protection at the valleys. The metal is cut with hand shears to
match the horizontal course lines.
Hips. Hips are treated pretty much the same as the ridge,
except for the angled cuts (Figure 10). We use
minimum-14-inch-wide slates to avoid small pieces.
10.Like valley slates, hip slates
are cut from full-size pieces. To provide support at the narrow
edge of the triangular slate, the top of the link channels can
be cut down to fit between the top batten and the wooden nailer
that runs along the hip.
Starter course. There's nothing special about the starter
course on a Nu-lok roof, as long as the batten layout has been
done right. There's no doubling — just a single
Nu-lok advertises its roof as "walkable," but as with any roof,
this should be left to professionals. It's not a good idea to
walk in the valleys, and wherever I walk, I use caution, try to
stay flat-footed, and put my weight over the battens.
Waiteruns Ron Waite Construction
LLC in Pawlett, Vt.