Low-Slope Reroof with EPDM, continuedMain course. We followed the same sequence to
install successive rows of roofing: Snap a guideline at the
center release mark, remove the lower release liner, broom the
membrane into place, then slide the upper release liner out,
leaving the 4-inch-wide release liner at the overlaps
temporarily in place.
For economy of motion, I chose to install the membrane
horizontally, rolling it directly from one end of the roof to
the other, despite the fact that once it passed over the hip,
the membrane ran parallel to the watershed off the roof. Either
orientation seemed okay to me, as the overlaps would all be
glued and sealed. Arguably, the vertical direction has an
advantage, in that water shedding off the roof won't puddle
behind any horizontal laps. We applied a stock aluminum drip
edge around the roof edge for aesthetics and to direct runoff
into the gutter (Figure 3).
3. A standard 2 1/2-inch-wide aluminum drip edge
is installed over the membrane to provide a
clean-looking perimeter and direct water into the
gutter. An EPDM cover strip will be applied later to
seal the material transition.
Sealing overlaps. When a roll ends short of
the end of the roof, an overlapping seam of at least 4 inches
is required. Before bonding the seam, you have to apply
proprietary adhesive primer to the overlap area, using a clean
cotton rag, and allow it to dry completely, which takes 5 to 15
minutes. It's a good idea to outline the overlap area with a
pencil first to guide the primer application. After the primer
dries, remove the release liner and fold the lap over into
place (Figure 4), removing just enough of the 4-inch release
strip at the bottom edge to allow full-width adhesion of the
lap joint. To ensure a solid bond and remove any air bubbles,
all laps must be thoroughly worked with a hand roller across
the joint, end to end. The best tool for the job is a
heavy-duty, steel hand roller.
4. Splices in a course must be prepared with a
proprietary primer before joining with a minimum 4-inch
overlap. Peeling back a short length of the separate
4-inch-wide parting strip along the bottom edge allows
full-width bonding of the splice.
Of course, the overlaps between courses have to be bonded
together. Where the upper layer of roofing laps the lower,
trace the overlap area with a pencil, apply primer, let it dry
and press the lap into place, while progressively pulling the
4-inch-wide release liner away (Figure 5). When a course
overlaps a splice in the course below it, I apply a bead of
WeatherBond sealant to the edge of the splice and bed the upper
lap into the uncured sealant.
5. With all of the courses installed, the author
goes back and prepares the overlaps with primer before
peeling off the 4-inch-wide protective strip and
bonding the edge. A vigorous follow-up treatment with a
wood or steel seam roller assures a good seal without
bubbles or blisters.