What is an as-built survey?
An as-built survey (also called a record survey or post-construction survey) verifies that the completed construction matches the design drawings and the building regulations approval. It produces an accurate measured record of the building as it actually exists on site, with a comparison against the issued construction or IFC drawings, and a schedule of any deviations.
An as-built survey is the right answer at any point where the as-built condition needs to be confirmed against the design — typically at practical completion (just before handover to the client or FM team), at each phase handover in a multi-phase project, or as part of a snagging exercise to identify defects before final payment to the contractor.
2026 cost bands
A 2026 as-built survey in the UK typically lands in the following bands (ex VAT):
| Project | Typical 2026 cost | Notes |
|---|---|---|
| Small residential / single building | £500–£1,200 | 1 day on site |
| Medium development / small commercial | £900–£2,000 | 1–2 days on site |
| Larger commercial or infrastructure | £2,000–£5,000+ | 2–4 days on site |
| BIM verification (Revit vs as-built) | £1,500–£4,000+ | Per LOD band |
A 2026 as-built survey typically achieves an accuracy of ±10–25 mm for typical residential and commercial work, with tighter accuracies available for specialist projects. The accuracy is sufficient to identify deviations from design that would affect the building's use, function, or compliance.
What's included in a 2026 as-built survey
A standard 2026 as-built survey includes:
- Site measurement of the completed works — structure, M&E locations, hard landscaping, levels — to an agreed grid and datum using total station, GNSS, or laser scanning.
- Capture of key coordinates, levels, and features for comparison with the issued construction or IFC drawings.
- As-built CAD plans, sections, and (optionally) a 3D model in DWG + PDF, with a schedule of deviations where relevant.
- Deviation report — a written schedule identifying where the as-built condition deviates from the design, with a magnitude and a pass/fail flag against the agreed tolerance band.
- Verification against tolerance bands — for civils work, a check against the design tolerance for highways, drainage, utilities, slabs, and kerb lines.
When to commission an as-built survey
An as-built survey is the right answer at any point where the as-built condition needs to be confirmed against the design:
- Practical completion (just before handover to the client or FM team) — the most common trigger for a 2026 as-built survey.
- Phase handover in a multi-phase project (e.g. a 3-block residential development) — each block's as-built condition is confirmed before the next block starts.
- Snagging — a pre-completion check to identify any deviations that need to be corrected before the contractor's final payment.
- BIM verification — a comparison of the as-built Revit model against the design model to confirm construction matched the BIM.
- Dispute resolution — when there is a disagreement between the contractor and the client about whether the construction met the design, an as-built survey is the independent evidence.
- Insurance claim — when a property has been damaged and the insurer needs to confirm the as-built condition before the claim is settled.
- Pre-acquisition due diligence — when a buyer needs to confirm the as-built condition of a commercial property before exchange.
Methodology
A 2026 as-built survey typically uses a combination of:
- Total station — for precise angle and distance measurement to individual features (columns, walls, drainage covers).
- GNSS (GPS) — for OS grid-referenced positions of features across the site.
- Terrestrial laser scanning — for high-density coverage of complex areas, with the point cloud registered to the rest of the survey.
- Drone photogrammetry — for the broader site overview, especially for earthworks and external areas.
The 2026 default is a combined approach: total station for the structural elements, drone or laser scan for the broader site, and a CAD production phase to bring everything together.
Turnaround time
A 2026 as-built survey typically delivers in:
- Small building / plot — 1 day on site, 3–5 working days for outputs (faster if fewer drawings).
- Larger commercial / estate — several days' fieldwork, 1–2 weeks for the full drawing set and QA, especially for BIM deliverables.
Express turnaround is available at a 25–50% premium.
How to commission an as-built survey
- Send the project address and a brief. Outline the project (residential extension, new build, commercial development), the size in m², the deliverable requirement (2D CAD, 3D model, BIM verification), and any specific tolerance band required.
- Receive a fixed-fee quote based on the project scope. Most 2026 quotes are returned within 24 hours.
- Site visit. 1 day on site for a typical residential project; 2–4 days for a larger commercial or infrastructure project.
- CAD production. 3–10 working days for the standard scope.
- Issue deliverables. As-built drawings (DWG + PDF), deviation report, and (for BIM) the as-built Revit model.
An as-built survey is the right answer for any project where the as-built condition needs to be confirmed against the design. Without an independent as-built record, handover disputes, FM data gaps, and contractor claims all become harder to resolve — and the cost of a £1,500 survey is dwarfed by the cost of a single unresolved handover dispute.
Frequently asked questions
When should an as-built survey be done? At practical completion, just before handover to the client or FM team. This is the most common 2026 trigger. The next most common is at each phase handover in a multi-phase project (e.g. a 3-block residential development), where each block's as-built condition is confirmed before the next block starts. As-built surveys are also used for snagging, dispute resolution, insurance claims, and pre-acquisition due diligence.
Is an as-built survey the same as a snagging survey? No. A snagging survey is a defects survey — a list of items the contractor needs to fix before final payment. An as-built survey is a measured survey — a record of the as-built condition against the design. The two are often commissioned together: the as-built survey gives the measured record, the snagging survey gives the defects list. For a typical 2026 residential project, the combined scope is in the £1,500–£3,000 band.
What tolerance is normal for an as-built survey? A 2026 as-built survey typically works to ±10–25 mm for typical residential and commercial work. Tighter tolerances (±2–5 mm) are available for specialist work (steel structures, machine installation, monitoring). The tolerance is agreed in the project specification.
Can the as-built survey verify against the BIM model? Yes. A 2026 as-built BIM verification is a defined scope: the as-built Revit model is overlaid on the design Revit model, and any geometric deviation is flagged. This is the right scope for any project where the design and construction teams are working in BIM, and it produces a deviation report that can be used to validate the contractor's application for payment.
What does the deviation report look like? A standard 2026 deviation report lists each measured feature (column position, slab level, drainage cover level, kerb line, etc.), the as-built coordinate, the design coordinate, the magnitude of the deviation, and a pass/fail flag against the agreed tolerance. The report is delivered as a PDF and (typically) as a DWG with the deviations colour-coded.