BIM IQ

As-Built vs As-Planned: How to Compare Site Reality with the Schedule and the Model

By Kush Agarwal, President and CEO, YelloSKYE. Published 2026-10-22.

Executive Summary

• The Question: What is the difference between as-built and as-planned, and how do you compare them while there is still time to act?
• The Answer: As-planned is the approved programme and design; as-built is the verified record of what was built, when and where. The comparison is only as good as the site evidence behind it, so it should run on a fixed cadence using dated captures, not self-reported percentages.
• The YelloSKYE Angle: Multi-sensor capture feeds both checks: progress against the programme, and geometry against the model through BIM IQ, all held in one time-linked record on DEX.

As-built vs as-planned: the short answer

As-planned is what the project agreed to build and when; as-built is the verified record of what was actually built, when and where. Comparing the two tells you which activities have slipped, which elements are out of position, and whether either gap threatens completion, cost or the next trade.

Most teams treat this as a schedule exercise. In practice there are two comparisons running at the same time. One is about time: did the activity start and finish when the baseline programme said it would? The other is about geometry: is the column, slab edge, shaft or sleeve where the drawings and the BIM model say it should be? A project can be on programme and still be building the wrong thing, or be dimensionally perfect and three weeks late. This guide covers both, and how BIM IQ and the wider YelloSKYE stack help developers, EPC contractors and PMOs keep each one honest.

The two dimensions of as-built vs as-planned

The two checks share one requirement: an as-built record that is dated, located and objective. Without that, both comparisons fall back on what someone reported rather than what is on site.

Why "as-reported" is not "as-built"

On many projects the progress figure that goes into the monthly report is a percentage entered by a site engineer or the contractor. That figure is useful, but it is a claim, not a record. A floor marked 80% complete may have blockwork done and plastering not started, or services rough-in missing in two flats. When the same percentage also drives the contractor's progress payment claim, the incentive to round up is obvious.

A genuine as-built record is something a third party can check later: a timestamped image, an orthomosaic, a scan, tied to a specific location. If your comparison uses reported numbers on one side, it is really "as-planned vs as-reported", and the gap it hides tends to surface late.

Where the gap between plan and reality opens

Slippage rarely announces itself. It usually starts in one of these places:

• Coarse activities. A single programme line such as "Floor 7 finishes" can hide dozens of sub-steps. The activity can look nearly done while one missing step, say waterproofing in wet areas, is holding up tiling.
• Partial completion logged as complete. Shuttering is struck, but cube results or post-pour checks are pending. The activity reads finished; the next trade cannot start.
• Out-of-sequence work. A contractor moves to a tower that is ready instead of the one the programme expects. Totals look fine, but the planned sequence and the actual sequence diverge.
• Geometric drift. A column poured slightly off grid, a slab edge out of level, or a shaft that narrows over several floors. None of this shows in a progress percentage, and it often goes unnoticed until MEP contractors arrive with prefabricated runs that no longer fit.

The last point is where a schedule-only comparison falls short. Our as-built vs BIM clash detection use case describes exactly this pattern: a structural deviation that looks trivial on site becomes a stoppage weeks later, when the next trade tries to install against the design.

How to compare as-built with as-planned: a practical workflow

The steps below work for a single building or a portfolio. The point is to repeat them on a fixed cadence, not to run them once when a dispute is already under way.

1. Freeze the baseline

Confirm the approved programme, its data date and its critical path, and confirm which drawing revision and model version are current. If the baseline keeps changing informally, there is nothing stable to measure against. The US Government Accountability Office's Schedule Assessment Guide makes the same point: a well-built, approved schedule is the basis for measuring performance.

2. Tie activities to locations and elements

Map each programme activity to the towers, floors, zones or grid lines it covers. On BIM projects, link activities to model elements as well. This is what lets a captured image or scan be read against a specific activity instead of a vague "site overview".

3. Set a capture cadence that matches decisions

Choose the sensor to fit the question:

• Drones for site-wide progress, earthworks, façades and multi-acre layouts, delivered as orthomosaics, 3D models and video.
• 360° cameras for interiors, where drones cannot see.
• Fixed cameras for continuous records and time-lapse of critical zones.
• Laser scanners for geometry that must be checked against the model, after key structural milestones.

Align progress captures with review meetings and payment cycles. Align scans with pours, steel erection and the hand-off to services.

4. Verify, do not estimate

Compare the capture with the programme activity or the model element, and record what is actually installed. For geometry, BIM IQ registers the point cloud to the project's coordinate system and overlays it on the design model, so deviations show up as measured offsets rather than opinions.

5. Compare by zone, trade and element

Look at the variance where the work happens: which tower, which floor, which contractor, which element. A trade that looks slow overall may simply be working in a different zone because the planned one was not ready.

6. Feed the result into decisions

Take the findings into the lookahead, manpower and material plans, the programme update, payment certification and the coordination meeting. A comparison that does not change a decision is just a report.

Which deviations to act on first

Not every gap deserves the same response. A simple triage keeps attention on what threatens completion or creates rework.

The order matters. Geometry problems are cheapest to fix before the next layer of work covers them, so they often deserve action before a schedule variance of similar size.

The as-built record as evidence

As-built vs as-planned comparison has a long history in delay analysis, where experts reconstruct what happened after the fact. AACE International's Recommended Practice 29R-03 on forensic schedule analysis treats the comparison of the planned schedule with the as-built record as one of its recognised observational methods. In the UK, the Society of Construction Law's Delay and Disruption Protocol stresses keeping the programme updated and maintaining contemporaneous site records.

Whatever method is used later, it depends on knowing when each piece of work actually happened. When that record is thin, people rebuild it from diaries, WhatsApp photos and email threads, and every gap becomes a point of argument. A weekly as-built record removes most of that work. The same captures that flag a slipping trade in month three are the evidence you need if a claim or a billing dispute surfaces in month eighteen. Our use case on resolving contractor billing disputes shows how cycle-aligned drone capture supported that kind of verification, with 80% fewer site visits needed.

How YelloSKYE supports the comparison

YelloSKYE combines multi-sensor capture, engineering processing and one shared platform, so the time check and the geometry check run on the same record.

Progress against the programme

Construct IQ captures site progress with drones, 360° cameras and fixed cameras, and delivers orthomosaics, milestone imagery and video that teams can review against the baseline. In our construction progress capture work, flying the site once a week took more than 15 hours of manual reporting off each site manager's week, and stakeholder meetings that used to run for two hours now finish in 30 minutes.

Geometry against the model

BIM IQ handles the second dimension. Point clouds from laser scanners and drones become as-built BIM models at LOD 300–400, accurate to ±5 mm, which are then laid over the design model so that misplaced structural elements, MEP conflicts and other deviations stand out. Input can come from Leica, FARO, Trimble, Matterport and other major scanner brands, as .e57, .las, .rcp, .pts, .xyz and similar files, and the resulting models open in Revit and AutoCAD.

One record on DEX

DEX holds drone surveys, 360° captures, scans and BIM models in a single time-linked environment. Teams can overlay CAD or BIM models on site visuals, scrub back through months of site history, and measure distance, area and volume from their desks. Planning, QA, the PMO and leadership look at the same evidence, which turns the progress review from a debate about numbers into a discussion about what to do next.

Common mistakes to avoid

• Comparing against a moving baseline. Lock the programme and model version before you measure.
• Capturing only when there is a problem. A record that starts in month nine cannot explain month four.
• Treating geometry as a handover task. Scanning only at completion produces a good as-built model but misses the chance to prevent rework.
• Keeping evidence in personal phones and chats. If it cannot be found, dated and located, it does not count as a record.
• Leaving the comparison to one team. Planning, site execution and BIM coordination each own a piece; they need one shared view.

Bringing the two comparisons together

As-built vs as-planned is not a closeout report. It is a running check on two questions: are we on time, and are we building what was designed? Projects that answer both every cycle, from dated multi-sensor captures rather than reported percentages, catch drift while it is still cheap to fix and carry a complete record into handover, billing and any dispute that follows. For the geometry side, start with BIM IQ; for progress, pair it with Construct IQ, and bring both together on the DEX platform.

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