3.6
METAL FLASHING
Metal flashing shall be as shown at intersections of vertical or projecting
surfaces through the roof or against which the roof abuts, such as walls,
parapets, dormers, and sides of chimneys. Flashing installation shall be
in accordance with Section 07600 FLASHING AND SHEET METAL.
3.7
SLATING
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NOTE: The best guide to traditional slating
installation procedures is "Slate Roofs", published
in 1925 by the National Slate Association. A
reprint was issued in 1977 by the Vermont Structural
Slate Co. The Steep Roofing Section of the National
Roofing Contractors Association Roofing Manual
contains a section on Slate Roofing which is
essentially an abridged and edited version of the
original 1925 publication.
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3.7.1
Repair and Replacement
Existing reusable slates removed from the repair area shall be intermingled
with new slates to provide a smooth visual transition between new and
existing areas. Slating shall be applied as shown.
3.7.2
Slate Coursing
The slate shall project 50 mm 2 inches at the eaves and 25 mm 1 inch at
gable ends, and shall be laid in horizontal courses with 75 mm 3 inch
headlap (unless otherwise indicated), and each course shall break joints
with the preceding one by at least 75 mm 3 inches. Slates at the eaves or
cornice line shall be doubled and canted 6 mm 1/4 inch by a wooden cant
strip, using same thickness slate for under-eaves at first exposed course.
Under-eave slate shall be approximately 75 mm 3 inches longer than exposure
of first course. There shall be no through joints from the roof surface to
the underlayment.
3.7.3
Nailing
Each slate shall be fastened with a minimum of two copper nails of
sufficient length to penetrate the roof decking at least 19 mm 3/4 inch or
through the decking thickness, whichever is less. Where the underside of
roof decking is exposed to view, such as in overhanging eaves, the nails
shall be long enough to penetrate the roof decking but not so long that
they may be driven through the decking. The heads of slating nails shall
just touch the slate and shall not be driven "home" or draw the slate, but
left with the heads just clearing the slate so that the slate hangs on the
nail. Nails in slates overlapping sheet metalwork shall not puncture the
sheet metal. Exposed nails are permissible only in top courses where
unavoidable. Exposed nail heads shall be covered with elastic cement. Hip
slates and ridge slates shall be laid in elastic cement spread thickly over
unexposed surface of under courses of slate, nailed securely in place and
pointed with elastic cement.
SECTION 07310
Page 11
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