PRELIMINARY CALCULATOR · PROTOTYPE V8

Roof Drainage Calculator

Estimate flow, outlet requirements, and preliminary pipe sizes. Network design and product selection require verification before construction.

Example scale:

ROOF & RAINFALL PARAMETERS

EN 12056-3

Total effective drainage area

Use project rainfall data; the values above are examples only.

Flat roof: 1.0 | Metal: 1.0 | Gravel: 0.9

Anti-Vortex

Elevation difference between gutter and discharge manhole

VERTICAL & HORIZONTAL COLLECTORS

EN 12056-3 Table 5 — horizontal collectors

0.0% for siphonic (flat). 0.5%–2.0% for gravity pipes.

TOTAL DESIGN FLOW
EN 12056-3 ROOF DRAINAGE
0.00 L/s
Q = (C × I × A) / 3600
Per drain: -- L/s • Awaiting parameters
READY TO CALCULATE
Total Q
0.00 L/s
Per Drain
-- L/s
Drop Head (ΔP)
-- m (-- kPa)
Drains
--
VERTICAL PIPE
DN --
Awaiting parameters
HORIZONTAL PIPE
DN --
Awaiting parameters
VERTICAL STACK — FILL ≤ 50% ISO 4427 / EN 12056-2
DN (mm) Capacity (L/s) Velocity (m/s) Actual Fill Status
HORIZONTAL COLLECTOR — FILL ≤ 70% · SLOPE 1.0% EN 12056-3 Table 5
DN (mm) Capacity (L/s) Velocity (m/s) Actual Fill Status

Design Flow Distribution

TOTAL DESIGN FLOW
0.00 L/s
Q = (C × I × A) / 3600
PER DRAIN POINTS
Design Assessment
DESIGN CHECK
Enter the roof area and parameters to start the preliminary calculation.
PARAMETERS
Roof Area: -- m²
Rainfall: -- mm/h
Roof Drain: Auto
Drop Head (H): -- m
Slope: 0.0%
Available Head (ΔP): -- kPa
Total Q: 0.00 L/s
Downpipe Assumption

Awaiting parameters.

EN 12056-3 Reminders
  • • Emergency overflow drain always required
  • • Min. 2 drain points per drainage area
  • • Consider 100-year return period rainfall
  • • Siphonic systems need specialist design
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