Foundation excavation: what to check before starting the work?

Foundation excavation is one of the first important stages of a construction. An error in setting out, depth or level can affect the following stages.

Checking the design

Before excavation, clear information must be available on:

• The position of the building
• The dimensions of the foundation
• The depth of the cut
• The foundation level
• The width of the trenches
• Possible level differences
• Zones for basement or cellar

Setting out the building

The setting out must follow the design. The axes and the limits of the cut must be clearly marked.

Checking the utilities

The existing routes must be checked for:

• Water
• Sewerage
• Gas
• Electricity
• Telecommunications
• Drainage or old pipes

Choosing the machine

The machine is selected according to:

• The size of the work
• Access
• The type of terrain
• The depth
• The manoeuvring space
• The quantity of soil

Managing the excavated soil

It must be decided in advance:

• How much soil is kept
• Where it is temporarily stored
• How much is removed
• Whether the soil can be reused
• How trucks enter the site

Type of soil

Clayey, sandy, rocky soils or uncontrolled fills behave differently during excavation.

Water in the cut

Rain, the water table or seepage can cause water accumulation and instability of the cut walls.

Checking the levels

During excavation the following must be controlled:

• Depth
• Level
• Dimensions
• Position of the cut
• Stability of the edges

Common mistakes

• Excavating too deep
• Storing soil too close to the edge
• Lack of access for the concrete pump
• Not protecting the cut from rain
• No level checks
• Damaging utility routes