Excavation crews work from drawings, and the quality of those drawings has a direct effect on how efficiently and safely the dig goes. When information is missing or unclear, crews either have to stop and ask or make assumptions, and both can cost time and money. Here is what foundation excavation contractors typically need from your engineer before they can plan and price the job properly.

Footing depths and elevations

The most basic requirement is a clear set of elevations: the top of footing, bottom of footing and finished floor levels, all tied to a known benchmark. Without these, the crew cannot dig to the right depth or confirm that the building will sit correctly relative to the street and neighbouring lots. Elevations should match the approved grading plan.

Footing sizes and layout

Width and thickness of footings, locations of pads for columns and any stepped footings on sloping sites all affect how the excavation is shaped. The crew uses this information to decide how much extra room to leave around the footprint for formwork and drainage.

Soil information

If a geotechnical investigation has been done, the report should be shared. It tells the crew what soil to expect, the depth to groundwater and any specific requirements, such as removing soft material or protecting the bearing surface. In Ottawa, where sensitive clay and shallow bedrock are both common, this information can change the approach entirely.

Bearing capacity and inspection requirements

Engineers often specify the soil bearing capacity assumed in the design and whether they need to inspect the excavation before footings are poured. The crew needs to know this so they can schedule the inspection and avoid leaving the excavation open longer than necessary.

Excavation support and safety

For deep excavations or those close to property lines or existing buildings, the engineer may design shoring, underpinning or specific slopes. These details must be on the drawings so the excavation can be planned safely and in line with Ontario's construction safety regulations.

Drainage and waterproofing

Perimeter drain locations, sump pit position, waterproofing systems and any requirements for clear stone or filter fabric affect both excavation size and backfill. Knowing these early lets the crew plan for material deliveries and the right sequence of work.

Backfill specifications

The engineer may specify what material can be used against the foundation walls, how it should be compacted and when backfill can start relative to floor framing. In clay soils, imported granular backfill is common near the wall. The crew needs these details to price material and plan hauling.

Services and connections

Locations and depths for water, sewer, storm and electrical services help the crew plan trenches and avoid conflicts. If services cross the excavation or run close to footings, the drawings should show how they will be handled.

Why the details pay off

Clear engineering information lets the excavation team build an accurate quote, order the right materials and schedule inspections efficiently. It also reduces the risk of costly mistakes, such as digging too deep, undermining a neighbour's foundation or placing footings on unsuitable soil.

If you are a homeowner managing your own project, ask your engineer to review the drawings with your excavation contractor before work begins. Good foundation excavation contractors will appreciate the chance to ask questions, and that short meeting can prevent many problems in the field.