Patio Fall Calculator

Total fall, high and low points, puddling warnings.

All calculators

Inputs

Run(m)

Fall ratio (1:x)

Site context (optional)

Helps tailor algae, weather and longevity advice.

Aspect

Exposure

Confidencelow· 42Complexitylow· 10

Run: 4m
Fall ratio: 1:80
Total fall: 50mm
High point (above low): 50mm
Low point: 0mm

Heads-up: Fall is always away from the house (or to a channel drain that takes it away from the house). 1:80 = 12.5 mm drop per metre of run. Why it matters: Reverse falls or shallow falls cause damp, frost lift and slip risk.

This app provides general UK guidance and material estimates only. It is not legal, planning, engineering or building-control advice. Always confirm requirements with your local planning authority, building control, utility providers, manufacturers or qualified professionals.