How Long Does an As-Built Survey Take?

Stage 1: scoping and access

Before anyone arrives on site, scope must be defined and access arranged. In an occupied building this means tenant notification, after-hours building permission, escorts for secured or mechanical areas and sometimes site induction. For institutional and industrial facilities, security clearance and safety onboarding can be the longest single item in the whole project.

This stage is almost entirely outside a scanning provider's control, which is why supplying access constraints with your initial enquiry has more effect on delivery date than anything else you can do.

Stage 2: field capture

Field time scales with the number of scan positions required, which is driven by geometry rather than raw area. Open spaces need few positions for a lot of floor area; subdivided floor plates, stairwells, corridors, plant rooms and small offices need many. Occupied spaces add coordination time between rooms.

Capture is usually the shortest stage of the four and the one clients most often assume is the whole project.

Stage 3: registration and processing

Scans must be aligned into a single coordinate system, checked against control, cleaned of transient objects such as people and vehicles, and prepared for use. Processing time scales with dataset size and with how difficult registration is, so feature-poor corridors and long buildings take longer than compact, geometrically rich ones.

This stage produces the registration report that documents achieved accuracy, and it cannot be skipped without giving up verifiability.

Stage 4: drafting or modelling

Deliverable production is normally the longest stage and the one most sensitive to scope. A set of 2D floor plans is considerably faster than a coordinated multi-discipline Revit model of the same building, and each additional discipline adds work.

It is also where review time lives. Building in a client review cycle before final issue avoids the more expensive pattern of revising a completed set after distribution.

What compresses a schedule and what does not

The most effective way to hit a tight deadline is phased delivery: capture the whole building once, then issue the areas your critical path needs first while the remainder is drafted.

• Compressible: drafting and modelling, by narrowing scope or phasing delivery area by area.
• Compressible: processing, by prioritising the areas needed first.
• Partly compressible: field capture, by deploying additional crews where access allows.
• Rarely compressible: access approvals, security clearance and tenant notification periods.
• Not compressible without cost: quality control, which is what makes the deliverable defensible.