14
roofing material. Weather proof with appropriate sealant. Consult the waterproofing and
roof attachment drawings
Details Q – Z in the Appendix
for additional details.
In retrofit situations, rafters or roof trusses may be located from inside the attic if the
crawl space is large enough to permit access. Small galvanized nails may be driven up
beside the rafters at the desired anchoring point; this locates the penetration points for
the installers on the roof. Measure and mark the four roof penetration points for the
mounting bolts.
If access to the attic is not adequate, trusses can be located by looking or nails in the
facia board. They show the location and spacing of the trusses. Locate the mounting
points by measuring across the roof ridge and popping a chalk line between the ridge
and the facia along the run of the truss
see Drawing G
. The may not be perfectly
straight, so the chalk line will be close to, but not precisely on, the truss run. Many
installers use the variation in tone associated with external hammer blows to locate the
run of the truss.
Most roofs are either asphalt or fiberglass shingles. They are stapled or nailed in an
overlapping pattern over the felted plywood that comprises the roof sheathing. Old
brittle asphalt shingles may break underfoot. Use care until the condition of the shingles
is determined. Mount bases can be installed directly over pliable shingles; no special
preparation is necessary. Holes for the anchoring bolts should be drilled through the
shingles. The penetration holes should be completely encircled with roof sealant to
provide a watertight seal.
Roofs with hard, non-flexible shingles such as cedar shake and asbestos should be
treated the same as tile roofs.
Standing seam metal roofs are treated much the same as flexible shingle roofs. The
mount bases can be installed directly over the metal sheathing. On corrugated metal
roofs the penetrations must be made on the crown of the corrugation, never in the valley.
Special care must be taken when sealing this type of roof.
DRAWING F
2”X4” CROSS
BRACE
3/8” NUT AND BOLT
OR THREADER ROD
SPACER TO MATCH
RAFTER
RAFTER
TYPE 1
ROOFING
MATERIAL
TYPE 2
3/8” J BOLT
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