What Is an As-Built Survey and When Is It Needed?
Construction begins with plans showing what is intended to be built.
An as-built survey documents relevant conditions after improvements have been constructed or installed.
Depending on the project, an owner, contractor, engineer, architect, lender, utility, or public agency may need verification of the location or elevation of completed work.
That is where as-built surveying can become an important part of project closeout and construction documentation.
What Does “As-Built” Mean?
In simple terms, an as-built survey records selected improvements as they exist in the field after construction.
Instead of showing only what the plans proposed, the survey reflects measured conditions.
The exact scope depends on the project.
An as-built survey may document:
- Building locations
- Finished floor elevations
- Walls
- Curbs
- Pavement
- Drainage improvements
- Utility structures
- Pipes or infrastructure
- Site improvements
- Grading elevations
- Other constructed features
The appropriate level of detail should be determined before the fieldwork begins.
Why Might an As-Built Survey Be Requested?
An as-built survey may be needed for several reasons.
The project team may want to confirm that completed improvements are located as expected.
A civil engineer may need measured information for certification or record drawings.
A municipality or other agency may require particular information before project closeout.
An owner may want documentation for future maintenance or redevelopment.
A contractor may need survey verification before moving into the next phase of construction.
The purpose of the survey determines what should be measured.
As-Built Surveying Is Different From Construction Staking
Construction staking and as-built surveying occur at different points in the building process.
Construction staking transfers design information from approved plans into the field so crews know where improvements are intended to be constructed.
An as-built survey measures completed or partially completed improvements to document where they actually are.
A simplified way to think about the two is:
Construction staking: Where should it be built?
As-built surveying: Where was it built?
Many projects may use both services.
As-Builts Can Be Performed at Different Construction Stages
Not every as-built survey occurs at the very end of the project.
Some features become inaccessible after later work is completed.
For example, a project team may need documentation of underground utilities or other improvements before they are covered.
This means the survey schedule should be coordinated with construction.
Waiting until the project is finished may make certain measurements difficult or impossible to obtain.
Elevations Can Be Just as Important as Horizontal Locations
An as-built survey may involve both horizontal position and elevation.
Depending on the project, elevations may be important for:
- Grading
- Drainage
- Finished floors
- Curbs and gutters
- Utility structures
- Roads
- Pads
- Other site improvements
If elevation verification is required, that should be clearly identified in the survey scope.
The project engineer or architect may have specific points that need to be measured.
Provide the Surveyor With the Latest Plans
As-built work is much more useful when the surveyor understands what the project team needs verified.
Provide current construction documents whenever possible.
These may include:
- Civil plans
- Architectural site plans
- Grading plans
- Improvement plans
- Utility plans
- Landscape plans
- Approved revisions
- Agency requirements
If the plans changed during construction, provide the latest approved or relevant version rather than relying on an outdated set.
Define Which Improvements Need to Be Located
The phrase “as-built survey” can mean different things to different project participants.
One client may need only building corners and finished floor elevations.
Another may need a detailed survey of grading and site improvements.
A third may need utility features or infrastructure.
Before requesting a quote, determine as clearly as possible:
- What needs to be measured
- Which portion of the site is involved
- What accuracy or standards are required
- Whether elevations are needed
- What drawing or digital deliverable is expected
- Who will use the information
- When it is needed
A well-defined scope can prevent delays or unnecessary repeat fieldwork.
Construction Changes Make As-Built Information Valuable
Field conditions do not always match the original assumptions made during design.
Construction tolerances, unforeseen site conditions, approved revisions, utility conflicts, or other changes may affect the final location of improvements.
As-built measurements provide factual field information about completed conditions.
The architect, engineer, contractor, or owner can then use that information for the purpose appropriate to the project.
As-Built Surveys Can Support Future Work
As-built documentation may remain useful well after construction ends.
Future project teams may use the information when planning:
- Additions
- Remodels
- Site improvements
- Utility work
- Redevelopment
- Maintenance
- Property documentation
Accurate records of existing improvements can provide a useful starting point when the property changes again.
Schedule As-Built Surveying Before Critical Features Are Covered
Construction schedules can move quickly.
If the surveyor needs to locate a feature before concrete placement, backfill, paving, landscaping, or another construction activity, advance coordination is important.
The contractor or project manager should notify the surveyor early enough to schedule the fieldwork.
Last-minute requests may be difficult to accommodate, particularly when a project depends on documenting an improvement before the next construction step.
What Information Should You Provide for an As-Built Survey Quote?
When requesting an as-built survey, provide:
- Property or project address
- Current plans
- Specific features to be surveyed
- Required elevations, if applicable
- Agency or engineer requirements
- Desired deliverables
- Construction schedule
- Deadline
- Site access information
- Project contact information
If another professional is requesting the survey, include that person’s requirements or contact information whenever possible.
Talk With Terwilliger About As-Built Surveying
Terwilliger Land Survey Engineers provides professional surveying services for owners, contractors, architects, engineers, developers, and construction teams throughout California.
If your project requires as-built documentation, provide the current plans, project location, required features, construction schedule, and intended use of the survey.
Defining the required measurements before fieldwork begins helps the survey team provide the information your project actually needs.
