Installation Guide

ROOF JUNCTURE DETAILS
Correct construction of roof junctures is vital
to ensure weathertightness. In the following
cases, where metal flashing is employed, it
should be no less than 26 gauge galvanized
steel (or acceptable equivalent). It should be
painted on both sides with a good metal or
bituminous paint. Flashing materials should
be painted after bending to maintain the
integrity of the coating.
Convex Juncture
On this type of juncture (Figure 9) metal
flashings should be installed to cover the top
100mm of the wall and the bottom 200mm
of the roof slope before the final course of
shingles or shakes is nailed to the top of the
wall. A narrow band of shingles or shakes—
or a strip of wood molding—should be
applied horizontally after the final wall
course is installed. A double or triple starter
course is then applied at the eave, with a
38mm overhang of the wall surface. The roof
can then be completed in the normal
manner.
Concave Juncture
Metal flashings for the concave juncture
(Figure 10) are similar to those for the
convex type. They should be installed to
cover the top of the roof slope and the
bottom 100mm of the wall before the final
course of shingles or shakes is installed.
The final roof course should be installed so
that the tips fit as snugly as possible against
the wall at the juncture. A double starter
course should be applied at the start of the
wall surface and the remaining wall courses
applied in the recommended manner.
Apex Juncture
On this roof juncture (Figure 11) metal
flashing should cover the top 200mm of the
roof and the top 100mm of the wall.
It should be installed before the final course
of shingles or shakes is applied to the wall.
The recommended sequence of application is
to apply shingles or shakes first to the wall,
then to the roof. The overhanging roof
material is then trimmed flush with the wall.
Finally, specially prepared ridge units are
applied over the wall-roof juncture so that in
each matching pair the roof piece overlaps
the wall piece each time.
Swept or Bell Eave
When shingles or shakes are to be applied to a swept or bell eave where the curvature is excessive, it may be necessary
to soak them for a period (usually overnight) or steam them prior to installation. A double starter course is employed
in the usual manner. Exposure is determined by the slope of the roof and the type of shingle or shake selected.
Double or triple
starter course
Narrow shingles applied
horizontally or wood molding
Metal flashing
Sheathing
Double starter course
Metal Flashing
Double starter course
Two last courses over
flashing
Metal
flashing
For excessive sweep
shingles may be
steam bent
Ridge cap
Last course
over flashing
Sheathing
Fig. 11: Apex Roof Juncture and Swept or Bell Eave
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Fig. 9: Convex Roof Juncture
Fig. 10: Concave Roof Juncture