Metal Roofing Options, continued
Modular panels are either nailed directly to the
roof deck or installed on 2x2-inch battens spaced approximately
14 inches apart (Figure 8). Installing battens is extra labor
but levels out surface irregularities caused by old roofing and
allows more elaborate profiles to be stamped into the panel.
Modulars installed without battens have folds along the sides
and bottom edge that hook on to preceding shingles and are
nailed directly to the roof deck, through the old roofing
(Figure 9). On both types, manufacturers specify felt or
polyethylene underlayment to keep sheathing and old roofing
from abrading the back of the panels and to offer some
protection as a secondary water barrier.
Figure 9.Modular panels are installed over felt or
proprietary underlayment either directly to the roof deck or on
2x2 battens. Systems without batten boards speed installation
by eliminating the need to cut and nail down the wood pieces,
but they can look flat compared to the deeply textured systems
that use battens.
Modular panels are frequently manufactured from the
lightest-gauge metal (.015 inch), but stamping patterns into
the metal adds strength, so careful footsteps are unlikely to
crush them, although walking on the highest raised portions of
the panel can be damaging. For roof areas with an unusual
amount of foot traffic -- adjacent to air-conditioning
equipment, for example -- manufacturers recommend optional foam
backers to reinforce raised portions of the panel.
Manufacturers offer many preformed accessory pieces that speed
installation, but complicated roof profiles can slow it
considerably (Figure 10). Hips and valleys require custom
cutting and bending, and although modular panels are easier to
cut than the concrete or clay tile they're often made to
resemble, you can't make cuts up on the roof with a utility
knife like you can with asphalt shingles.
Figure 10.As with standing-seam and
exposed-fastener panels, installing modular panels is made
easier by coordinating trim accessories. Clockwise from top
left are starter, hip cap, ridge caps, and rake trim from
Modular panels are the priciest form of metal roofing.
Depending on the metal used, the type of finish, and the
pattern, installed prices run from $500 to $1,000 per