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PLUMBING CONNECTION
SPRING 2015 41
This table states in the title line, ‘holes and weirs’. This is
the first real hint to an actual overflow but there is still no
reference to sizing or positioning. It also makes reference
to ‘level gutter’. Now I was taught at trade school that all
gutters must be installed with fall and on the VBA
Technical
Solutions Sheet 0.04
it states the following:
Step 2: Select eaves gutter and gutter slope. The eaves
gutter selected is quad spouting with an effective cross
sectional area of 6125mm² installed with a slope of 1:500. It
also refers to SAA/NZS 114: 1998 Appendix H
Above you will see the examples of ‘Provision for overflow’
shown in AS/NZS3500.3: 2015.
NOTE:
None of the examples have overflow slots.
DIAGRAM A:
EAVES GUTTERWITH LOW FRONT
These gutters are still available but are rarely used because
they expose the ends of the roofing material.
DIAGRAM B:
EAVES GUTTERWITH HIGH FRONT AND REAR
FLASHING
This is clearly designed by someone who has never
installed a gutter in their life. Yes the rear flashing will stop
overtopping but it effectively makes all common bracketry
for eaves gutter useless.
DIAGRAM C:
EAVES GUTTERWITH MINIMUM 10MM GAP TO
FASCIA
This is an effective provision for overflow, it is an extreme
level of overkill 12m x 10mm = 120,000mm2. Considering
that a 100 x 50mm downpipe pop is 5000mm2 this provision
gives you 24 times the required amount of overflow.
DIAGRAM D:
CONCEALED EAVES GUTTERWITH TAIL
Because this is an internal eaves gutter and can be formed from
one piece of sheet metal, not only will it work but it will work well,
but this type of install are one in a thousand these days.
DIAGRAM A
EAVES GUTTER WITH LOW FRONT
DIAGRAM B
EAVES GUTTER WITH HIGH FRONT AND REAR FLASHING
DIAGRAM C
EAVES GUTTER WITH HIGH FRONT AND MIN. 10MM GAP TO FASCIA
DIAGRAM D
CONCEALED EAVES GUTTER WITH TAIL
EAVES GUTTER
EAVES GUTTER
EAVES GUTTER
FASCIA
FASCIA
TAIL
CONCEALED
EAVES GUTTER
FASCIA
FASCIA
NO SEAL
REQUIRED
FLASHING
h
f
h
f
h
f
30mm min.
10mm min.
h
f