Knowledge that flows. Decisions that matter.Engineering partner: PT Rafa Jaya Persada ↗
Roof drainage knowledge for projects in Indonesia

Understand the flow.
Plan with confidence.

Explore siphonic systems, understand key design considerations, and estimate the initial drainage needs of your roof.

For building owners, MEP consultants, and project teams.

01 / SYSTEM ANATOMYCONCEPTUAL ILLUSTRATION
Roof drain9 outlets in 3 rows Level branch pipeszero gradient, no slope Collector pipecombines the branches Junctionall branches join Single downpipefull-bore, fast flow Underground connectionto the discharge drain Gravity: part-full + air Siphonic: full-bore, no air
From rooftop to understanding.Follow the flow ↗
Notes & insights

Keep your knowledge flowing.

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Planning tools

Start with your roof data.

Enter your roof area and rainfall intensity. Explore estimated flow, outlet requirements, and preliminary pipe sizes.

Try the calculator ↗
Q = C × I × A / 3600

Flow (L/s) · Runoff coefficient · Intensity (mm/h) · Area (m²)

An initial estimate to start your technical discussion.

From knowledge to your project

Better decisions start with the right questions.

Every roof has a different context. Use the resources and calculator to prepare for a discussion with the engineering team.

Explore case studies →

Understand your building

Building use, roof layout, location, and discharge routes.

Prepare your initial parameters

Catchment area, rainfall data, elevations, and project constraints.

Bring your results to the discussion

Support the estimate with drawings and technical review.

Have a project in mind?

Tell us the location, building type, and project stage.

Discuss your project ↗