

















EAVES GUTTER AND DOWN PIPE DESIGN TO AS/NZS 3500.3: 2015





Horizontal catchment area

Ah

=


sq.m


Roof slope

S

=


degrees


Intensity

I

=


mm/hr


Is Gutter slope steeper than 1:500 ?






Selected Number of Down pipes

n

=










From AS 3500 Table 3.4.5.2, Catchment Area Multiplier

f

=




Roof Area allowing for slope

Ac

=

Ah*f





=


sq.m


Catchment Area per DP

A

=

Ac/n

sq.m




=


sq.m


Flow/DP

q

=

I*A/3600

litres/sec




=


litres/sec


from AS/NZS 3500 fig 3.5.2(C), Gutter Area 

=


sq.mm 

Gutter Area rounded to nearest 100sq.mm


=


sq.mm


From AS/NZS 3500 Table 3.5.2,, Down Pipe size 

=


mm


(Interpolating between the standard sizes of the table. Info Only)

=


mm


Cross sectional area (Info Only)


=


sq.mm


Down Pipe size selected


=


mm


cross sectional area


=


sq.mm


Summary






This catchment requires : number of DP's


=




Downpipe size


=


mm


minimum eaves gutter cross sectional Area


=


sq.mm 

(note assuming the catchment area of each DP is roughly similar)





























