Quickly determine the right Cofferdam size for your project with our easy-to-use calculator.
Cofferdam Size Calculator
Sizing Your Cofferdam
Choosing the right size Coffer Dam helps to prevent water from seeping around the sides, and helps to ensure that the Dam won’t slip out of place during use.
- Identify the Maximum Water Level (A):
Determine the maximum water level that accumulated water could reach when the Dam is installed (see the diagram). Measure the ground distance from point (A) on one side of the bank to point (A) on the other side of the bank. Note: The ground distance is measured down the side of the bank, across the base of the stream bed, and up the other side. - Identify the Current Water Level Point (B):
Determine the current water level before the Dam is installed (see the diagram). Measure the ground distance from point (B) on one side of the bank to point (B) on the other side of the bank. - Adjust for Proper Length:
Add 20 inches to the measurements on each side to allow for a proper fit. - Compensate for Uneven Surfaces:
Add an additional 10% to the measurements to compensate for the fabric stretching over an uneven surface.
Sizing Formula: To calculate the total length needed, use the following formula:
[ Distance from (A) to (A) in inches + 40 inches ] x 1.10 = Total Inches Needed
For example: [ _____ inches + 40 inches ] x 1.10 = _____
Calculate Your Coffer Dam Size: You can use this formula manually to determine the right size for your project, or simply enter your measurements into the calculator on this page for a quick and accurate result!
Ensure Proper Coverage and Reusability: The Dam must be long enough to prevent the water from flowing out at the sides. Otherwise, it may slip out of place or allow water to escape at the sides. It does not hurt for the Dam to be longer than needed. A longer Dam may also facilitate its reuse for subsequent projects with slightly larger requirements.
Measuring for a U-shaped Cofferdam
- Determine the Maximum Retention Height (h):
Determine the maximum retention height necessary for the project. Add 8 inches to allow for unanticipated variances. - Calculate the Length of the Workzone (L):
Measure and calculate the total length of the workzone. - Calculate the Depth of the Workzone (l):
Measure and calculate the total depth of the workzone.
Determine the Length of Coffer Dam Needed:
Use the following formula to calculate the length of the Coffer Dam for your project, or simply enter your measurements into the calculator on this page for a quick and accurate result: