Construction & site-progress monitoring

What you actually get

• Scheduled progress capture flown to a repeatable plan, so week 12 lines up with week 2
• Dated 4K stills and video of the whole site for progress reports and claims evidence
• Orthomosaic site plans you can overlay on design drawings to check as-built against intent
• Stockpile and cut-and-fill volumetrics for valuations and earthworks tracking
• A shareable image record for clients, funders and the planning officer who asks

What it costs

£250–£600 per visit for most sites, with repeat-visit schedules usually priced keener than one-offs. The exact per-visit rate depends on site size and reporting depth — your quotes will state it plainly.

What moves the price

• Visit frequency — weekly, monthly or milestone-based; a regular schedule costs less per flight than a stack of one-offs
• Site size and complexity — a single plot vs. a phased 200-unit development
• Reporting depth — raw imagery only vs. orthomosaics, volumetrics and progress-comparison reports

What project teams actually use progress capture for

Progress capture is a repeat flight flown to the same plan at a fixed cadence — weekly, monthly or pegged to programme milestones. Monthly suits most builds. Weekly earns its keep during groundworks and frame, when the site changes faster than anyone can document on foot; once the building is weather-tight, aerial capture tells you less and the cadence can usually drop. What the imagery gets used for, in practice:

• Monthly progress reports and board packs — a dated aerial set replaces a page of prose and settles arguments about what was done when
• Funder drawdowns — visual evidence that the build matches what the drawdown schedule claims
• Coordinating subcontractors — laydown areas, access routes and storage clashes are obvious from the air and invisible from the gate
• Keeping remote stakeholders informed — clients and consultants see the whole site on the same day each period, not a curated corner on visit day
• The permanent project record — what was in the ground before the slab, where the services ran, what the neighbouring land looked like before work started

Stockpiles, cut and fill: where the volumes come from

The mapping flight produces a dense surface model of the site. Software measures any stockpile against a base surface and reports the volume in cubic metres; the same models compared visit to visit show how much material has actually moved, which is your cut-and-fill tracking and a useful check on the muck-away invoices.

For routine earthworks tracking, photogrammetric volumes flown consistently are well within useful tolerance. For figures feeding a formal valuation or dispute, ask for ground control or RTK positioning and a stated method in the quote — the price goes up, and so does the standing of the number.

Evidence for valuations and disputes

Interim valuations move faster when the QS can check claimed progress against a dated orthomosaic instead of a site-walk diary. Each capture is timestamped and georeferenced, so what was built by the 28th stops being a matter of recollection.

In a delay claim or adjudication, the value of the record is its consistency: same flight plan, same intervals, no gaps. Ad-hoc phone photos prove a moment; a capture schedule proves a timeline. Agree with your contract administrator what the record needs to show, then put that in the brief — pilots can time and angle captures to cover specific contentious areas.

Feeding BIM and 4D programmes

Orthomosaics and point clouds can be delivered georeferenced to your site grid, which means they drop straight over the design model for as-built-versus-intent checks: slab edges, penetration positions, drainage runs, anything visible from above.

If you run a 4D programme, scheduled capture is the verification layer — a dated record of what was actually standing at each data drop, set against what the model said should be. Name your coordinate system and target software (Revit, Navisworks, Civil 3D or otherwise) in the request and the files arrive ready to load instead of needing a conversion exercise first.

Flying over a live site: safety and exclusion zones

A competent pilot treats your site like any other contractor: RAMS submitted in advance, induction on arrival, and a flight plan agreed with the site manager before anything takes off. Crane operations are the main coordination point — flights are timed between lifts or routed clear of the slew radius.

Exclusion zones are simpler on construction sites than almost anywhere else. A fenced, controlled site where everyone present is briefed means there are no uninvolved people underneath the drone — which is precisely what the CAA rules care about. Your part is small: a named contact for the day and a mention at the morning briefing. Work doesn't need to stop.

What a visit actually looks like

Most of the work happens before the pilot arrives. The flight plan — a grid pattern for mapping plus a set of oblique angles — is built once and reused every visit, which is what makes week 12 directly comparable with week 2. On the day, expect sign-in, a short briefing, and flying that's usually finished within the hour for a typical site; large or phased developments take longer.

Weather is the honest variable. Strong wind and rain ground drones, so schedule visits with a fallback day either side. For a monthly record, a 48-hour slip costs you nothing — what matters is that each capture lands at roughly the same point in the period, flown to the same plan.

Accuracy: what the numbers depend on

Three things set the accuracy of any measured output: flight height, which fixes how much real ground each pixel covers; positioning, whether standard GPS, RTK/PPK corrections or surveyed ground control points; and the processing behind it.

For progress imagery, visit-to-visit consistency matters more than absolute accuracy — you're comparing the site with itself. For volumes or any measurement feeding a payment, ask each quote to state the positioning method and expected tolerance. A quote that names its method and tolerance is one you can hold to later.

When a drone is the wrong tool

An honest pilot will tell you when not to hire one. The common cases:

• Internal works — once the shell is up, progress happens indoors where a drone can't usefully see. Interior capture is 360-degree cameras or a person walking the floors; many teams pair that with external drone capture
• Continuous monitoring — a fixed time-lapse camera films all day, every day, and measures nothing. It's a different job, and plenty of sites run both
• Setting out and boundaries — that's a land surveyor with a total station. Drone data complements measured surveys; it doesn't replace them where legal precision is required
• Restricted airspace — a site inside an aerodrome flight restriction zone needs permission before anyone flies. Usually obtainable, occasionally not, and always worth flagging in your request so quotes account for it

The CAA and insurance basics, in plain English

Every commercial pilot needs a CAA Operator ID and a flyer qualification. For construction work, a GVC with an Operational Authorisation is the realistic standard: it permits flying closer to people and property outside the pilot's control than the basic rules allow, which matters at site boundaries, public footpaths and neighbouring buildings.

The distance rules, shortly: drones must not overfly people who aren't part of the operation. A briefed, controlled site makes everyone on it involved, which is why construction is one of the easier environments to fly in legally — the complications sit at the boundary, and that's exactly what the pilot's authorisation covers.

Public liability insurance is a legal requirement for commercial drone work, not a nice-to-have. Ask for the certificate, and check the cover level your principal contractor requires before the first visit rather than after.

Briefing pilots: what to put in the request

Pilots quote faster and tighter when the request covers:

• Site address and size, and roughly where the programme stands
• The cadence you want — weekly, monthly, milestone-based — and how long the programme runs
• Deliverables — dated stills only, orthomosaics, volumetrics, comparison reports, point clouds for BIM
• Coordinate system and target software, if outputs are going into a model
• Site induction requirements and typical crane activity, so the time on site is priced honestly
• Any contentious areas the record specifically needs to cover

What a good quote includes

Expect the quote to answer in kind: per-visit price and what committing to a schedule does to it, named deliverables with file formats, turnaround time after each flight, the positioning method behind any measured output, evidence of GVC and insurance, and who handles airspace permission if your site needs one. A quote that's vague on deliverables now will be vague on delivery later.

After the handover: files, ownership and retention

Standard practice is full-resolution handover: JPEG stills, GeoTIFF orthomosaics, LAS or LAZ point clouds, and PDF or web-based comparison reports. If your common data environment has naming conventions, say so up front rather than at week 30.

Ownership should be written into the engagement — the norm is that you get the imagery with full reuse rights, while the pilot may keep working files. Retention matters more than most teams expect: the record is at its most valuable at final account and through the defects period, which can be years after the last flight. Agree who archives and for how long, and get a copy into your own project record rather than relying on a supplier's hard drive.