Flood Elevation Margin
Compare lowest-floor elevation with base flood elevation and required freeboard.
Description
Freeboard is elevation above a base flood reference.
Freeboard is elevation above a base flood reference. The supplied required freeboard turns that difference into a signed margin.1
Compare lowest-floor elevation with base flood elevation and required freeboard.
When to use Flood Elevation Margin
Use this tool to compare lowest-floor elevation with base flood elevation and required freeboard.
Prepare the supplied policy terms, dates, assumptions or recorded indicators requested. Keep monetary amounts on one currency basis and select the applicable thresholds separately.
How to use Flood Elevation Margin and understand its results
- Prepare the supplied policy terms, dates, assumptions or recorded indicators requested. Keep monetary amounts on one currency basis and select the applicable thresholds separately.
- Enter lowestFloorElevationMeters, baseFloodElevationMeters, requiredFreeboardMeters using the field table and calculation rules, then run the tool.
- Read elevationDifferenceMeters, freeboardMarginMeters, meetsFreeboard. The explanation below defines the units, signs, ordering and any flags or placeholder values.
- If the tool reports an input issue, correct the values and run it again. Apply the stated assumptions when interpreting a successfully returned result.
| Input field | Meaning | Value type; see rules below | Requirement |
|---|---|---|---|
| lowestFloorElevationMeters | Lowest floor elevation (m) | number | Required |
| baseFloodElevationMeters | Base flood elevation (m) | number | Required |
| requiredFreeboardMeters | Required freeboard (m) | number; minimum: 0 | Required |
Enter finite signed elevations in meters and nonnegative required freeboard. Return difference, margin and inclusive margin≥0 flag.
difference=floorElevation−baseFloodElevation; margin=difference−requiredFreeboard Units, indexing, boundary conditions and exceptional cases are defined in the calculation rules above.
| Output field | Meaning | Value type |
|---|---|---|
| elevationDifferenceMeters | Floor minus base flood elevation (m) | number |
| freeboardMarginMeters | Margin over required freeboard (m) | number |
| meetsFreeboard | Meets supplied freeboard | boolean |
{
"input": {
"lowestFloorElevationMeters": 12,
"baseFloodElevationMeters": 10,
"requiredFreeboardMeters": 1
},
"output": {
"elevationDifferenceMeters": 2,
"freeboardMarginMeters": 1,
"meetsFreeboard": true
}
}Limitations and assumptions
Use a common vertical datum. No elevation survey, flood map, jurisdictional requirement or risk/premium calculation is supplied.
Numeric inputs must be finite. Follow the calculation-specific rules for overflow, underflow and exceptional cases. Missing required fields, extra fields, wrong value types and violations of the calculation rules are input errors. A successfully returned false flag is an evaluated outcome; its meaning is explained above.
Alternative or Complementary methods
Use Wind-Mitigation Credit: Apply wind-mitigation credits subject to a caller-supplied cap. For a complementary task, use Leak-Device Discount: Calculate leak-device premium discount and simple annual benefit.
References
-
Flood Elevation Margin — tool.io
Similar or alternative tools
- Wind-Mitigation Credit
Apply wind-mitigation credits subject to a caller-supplied cap.
- Leak-Device Discount
Calculate leak-device premium discount and simple annual benefit.