How It Works

Where Did the Water Go?

Left
Right
Roof runoff moves
Pooling in the middle
Roof slope
Almost flat
Water on roof
0.0 gal
Downspout capacity
8 gpm
Water in gutter
0.0 gal
Runoff captured
0%
Water leaked inside
0.0 gal

This test changes only the roof heights and gutter position. Storm size, roofing material, and gutter capacity stay the same.

GutterLOW EDGE
••• 6gpm in
Roof area 160 sq ft
×
Rain depth 1 in
≈
Estimated volume 100 gal
Received 0 gal
Stored 0 gal
Overflow 0 gal

1 in of rain on 1 sq ft yields about 0.623 gal. So 160 × 1 × 0.623 ≈ 100 gal.

Tank≈ 100 gal rain
Standing water100 gal
×
Water weight8.34 lb/gal
≈
Roof load834 lb
Design capacity625 lb
Longest span16 ft
Roof deflection0.0 in

The edge walls alone leave the full 16 ft roof span unsupported.

Support834 lb load

Roof Evidence Complete

Flow → Capacity → Water Load → Support

✓Flow DirectionProved by design
✓Flow BalanceProved in a larger storm
✓Rain VolumeProved with tank capacity
✓Water LoadProved with a centered support
← Perspective

Keep the Rain Outside

You just built this small house. Shape the roof, add a gutter, and put your design through a real storm test.