Field

What is a site survey in construction?

A site survey is a measured record of a property before construction: where the boundaries are, how the ground slopes, what utilities and structures exist, and where the new work will go. It also refers to the contractor's own pre-bid site walk.

Two construction professionals review paper plans beside a tablet at a jobsite workbench.
Plan reviews connect field conditions, drawings, and the next decisions on a job. AI-generated illustration.

In its formal sense, a site survey is work done by a licensed land surveyor that maps a property: boundaries, easements, elevations, buildings, trees, and utilities. Designers use it to fit the building to the land, and contractors use it to set out the work. In everyday contractor talk, "site survey" also means walking the site before you bid to see what the drawings do not show. Both matter, and the second one is often skipped.

Common types of site surveys

SurveyWhat it showsWhen it is used
Boundary surveyProperty lines, corners, easements, encroachmentsBefore design, purchase, or fencing
Topographic surveyGround elevations, contours, existing featuresGrading, drainage, and foundation design
Utility locate / subsurface utility surveyBuried pipes, cables, and conduitsBefore any digging; design of new connections
Construction staking (layout)Building corners, grid lines, elevations marked in the fieldStart of construction and during site work
As-built surveyWhat was actually installed and whereCloseout, for the owner and the city
Existing conditions surveyInterior and exterior condition of an existing buildingRenovations, additions, and pre-construction documentation of neighbors

The contractor's pre-bid site survey

Separate from the surveyor's work, a contractor should walk every site before pricing it. Many contracts include a clause saying the contractor has inspected the site and accepts the conditions it could reasonably have observed. Skip the walk and you may lose the right to claim extra cost for anything visible. A good walk checks access for trucks and equipment, overhead lines, the state of existing finishes, where power and water can come from, neighbors, and anything that contradicts the drawings.

A worked example

A GC prices a 6,000 square foot addition to a church. The drawings include a topographic survey that is four years old. On the site walk, the estimator notices a new storm inlet and a parking lot overlay that raised grade by several inches near the connection point. That changes the finished floor transition and the drainage tie-in. The estimator sends an RFI before bid day, and the owner orders an updated topo. Without the walk, the difference would have shown up during excavation as a differing site condition argument the GC would likely lose, because the change was visible.

Common mistakes

  1. Relying on an old survey without checking what changed on the ground.
  2. Treating a utility locate call as a full utility survey. Locate services generally mark public lines, not private ones on the property.
  3. Setting out the building from the wrong benchmark, so every elevation is off by the same amount.
  4. Skipping the pre-bid walk on small jobs, where a single surprise eats the whole margin.
  5. Not photographing the site and neighboring buildings before work starts, which leaves no defense against damage claims.

Related: as-built drawings, concealed conditions, field verification, and how to read construction plans for estimating. Smart Business Automator stores site photos, daily logs, and documents with each project; see estimate to project handoff automation.

Frequently asked questions

Who does a site survey for construction?

Boundary, topographic, and layout surveys are done by licensed land surveyors. Utility surveys may involve locate services and specialized firms. The pre-bid site walk is done by the contractor's estimator or project manager.

Does the owner or contractor pay for the site survey?

The owner usually provides the boundary and topographic survey as part of the design documents. Construction layout may be the contractor's cost, depending on the contract.

What is the difference between a site survey and a site investigation?

A site survey measures what is on and above the ground. A site investigation, often a geotechnical study, looks at soil and rock below it. Most projects need both.

Why does a pre-bid site walk matter?

Many contracts say the contractor accepts conditions it could have observed. A walk lets you price those conditions and raise questions before the bid, not after.

Written and edited by

Maurice Francois writes and edits construction operations guides for Smart Business Automator. More from Maurice on the Scaling Legends podcast.

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