How to build a dike with sandbags

Cross-section of a sandbag dike

In an emergency, a sandbag dike can provide good protection against flooding.

  • Only surround the house, not the property. Place the dike approximately 2.4 m (8 feet) from the house. It should not be placed up against the house. Place the bags of the bottom layer perpendicular to the direction of the dike or riverbank. Wherever possible, build the dike on firm ground; avoid building on snow or ice. To help the dike better withstand water pressure, dig a bonding trench and use it as a foundation, as shown in the diagram below.
  • Do not fill the bags completely. Partially filled bags bond together better and are less likely to shift.
  • Alternate the direction of the bags from one layer to the next (perpendicular to the dike, parallel to the dike, etc.). Alternating layers will make the dike stronger.
  • In order to avoid seepage, it is a good idea to weave a polyethylene sheet between the bags that are exposed to the water. The polyethylene sheet must extend from ground level up to the second to last layer.
  • Weave it between the bags as shown in the diagram.
Top of page