Flood Barrier Door Calculator
Enter the design flood depth, freeboard and opening width — and get the recommended barrier height and the indicative hydrostatic load on the barrier, plus a barrier-type suggestion. Indicative only — confirm with a structural/flood consultant.
Your opening
Water head expected at the doorway — from a flood study / past events.
Safety margin added above the design flood level (often 0.3–0.6 m).
Clear width the barrier must span.
Barrier height = flood depth + freeboard = 0.9 m. Hydrostatic load uses the triangular pressure of the 0.6 m water head (½·ρ·g·h² per metre, ρ = 1000 kg/m³, g = 9.81 m/s²). Indicative engineering estimate — not a substitute for a qualified flood/structural design.
Recommended barrier height
0.00 m
0.6 m design flood depth + 0.3 m freeboard · 1.2 m wide opening
Total load
2.12 kN
hydrostatic, on barrier
Per metre
1.77 kN/m
½·ρ·g·h²
Base pressure
5.89 kPa
max, at floor
Suggested barrier type · 0.60 – 1.00 m
Automatic / self-rising flood barrier
Float-actuated or powered barrier — deploys without manual labour; larger head needs a rated frame.
The water pushes hardest at the floor and the resultant force acts about 0.2 m above the base. Anchor the frame and slab to carry this load and overturning moment.
Hydrostatic pressure increases with depth
Gauge pressure rises linearly from zero at the water surface to a maximum of 5.89 kPa at the base — the classic triangular distribution. The area of this triangle (× width) is the total load.
Indicative — fresh-water density assumed; silty/sea water and dynamic (wave/debris) loads can be higher. Confirm with a structural/flood consultant.
Plan flood protection for the whole opening
DesignAI helps you choose a barrier type, frame and anchoring for your depth and width — and tells you what the flood/structural consultant must sign off.
How it works. Recommended barrier height is the design flood depth plus a freeboard safety margin. The hydrostatic load is the resultant of the triangular water-pressure distribution: force per metre of width = ½·ρ·g·h² (ρ = 1000 kg/m³, g = 9.81 m/s², h = water head), and the total = that × the opening width. The resultant acts about h/3 above the base, so the frame must resist both shear and an overturning moment.
Indicative only. These figures are a sizing first-pass — flood barriers and watertight doors are project-engineered. Real designs must allow for water density (silty/brackish/sea water is heavier), dynamic wave and debris impact, hydrostatic uplift, seepage, seal life and anchorage into sound structure. Get a vendor spec and have a qualified structural/flood consultant confirm the loads, frame and fixings before you build.
Cost & GST. Flood/watertight barriers typically run ₹40,000–₹3,00,000+ per door (supply-only, indicative, before 18% GST) depending on head, width and automation. Site frame, RCC surround and installation are extra.
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