We will survey all accessible floors in the property and provide plans showing all visible walls, windows, doors, spot height levels, ceiling/roof heights, window sill/head heights.
HEAG099 vs HEAG317: Specifying the Right Historic Building Survey
The brief that quietly goes wrong
A brief lands on our desk asking for a “Level 3 record” of a listed building. On paper it reads as thorough. In practice it says almost nothing about the one thing that decides whether the record is usable: how accurate the geometry needs to be, how it is controlled, and what format it must be delivered in.
That gap is where heritage projects lose time and money. A record can be rich in description and history yet carry drawings that do not hold true when a repair, a retrofit, or a structural intervention begins. The fix is not more effort. It is understanding which Historic England document governs which part of the job.
Two documents, two different jobs
Two publications sit behind almost every heritage recording brief in England. They are often quoted together and just as often confused.
HEAG099 (2016): the recording guidance
Understanding Historic Buildings: A Guide to Good Recording Practice. It defines the four Levels of Record, from a basic visual note up to a full analytical account of a building and its development.
Crucially, the Levels describe how much interpretation, description, and analysis a record carries. They do not, on their own, set the metric accuracy of the geometry behind any drawings.
HEAG317 (2024): the survey specification
Geospatial Survey Specifications for Cultural Heritage. This is the technical standard for metric survey, covering survey control, georeferencing, instrument accuracy, laser scanning, photogrammetry, point cloud registration, and archive-ready deliverables.
When a project needs measured, spatially accurate data, HEAG317 defines the deliverable.
Put simply, HEAG099 tells the story of a building. HEAG317 measures it. Good briefs use both, and know which one owns which requirement.
Where the two documents meet
The friction point is the top of the Levels of Record scale. A Level 3 or Level 4 record usually implies measured plans, elevations, and sections. But HEAG099 does not specify the accuracy, control, or georeferencing that reliable measured drawings depend on. That specification lives in HEAG317.
So the two are not alternatives. A higher-level interpretative record and a metric survey specification should be read together: HEAG099 sets the depth of understanding; HEAG317 sets the geometric backbone that the understanding is drawn onto.
The technical detail a brief needs to name
When we scope a measured survey of a heritage asset, these are the parameters that turn a vague “Level 3” request into data that survives the whole project life cycle.
Control and georeferencing
A survey control network ties every measurement together and, where required, georeferences the model to the Ordnance Survey National Grid. Without controlled data, plans and elevations drift out of alignment and cannot be trusted across phases.
Accuracy and registration
Instrument accuracy and point cloud registration tolerances decide how closely the record matches the real fabric. These need to be stated up front, not assumed.
Capture and resolution
Laser scanning and photogrammetry produce dense point clouds. Point density and photographic resolution should suit the finest detail the record must show, from moulding profiles to timber joints.
Deliverables and archiving
2D measured drawings, 3D meshed models, orthophotography, and Scan to BIM models each serve different needs. Archive ready formats and metadata that record method, control, and accuracy keep the dataset useful for decades.
Why a weak brief costs money later
Under-specified surveys rarely fail on day one. They fail at reuse. A record captured without control cannot be reliably georeferenced later. A point cloud without stated accuracy cannot support a confident repair design. A dataset with no consistent origin cannot be compared visit to visit, so it is useless for monitoring movement or deformation.
The result is familiar: incomplete plans, undocumented assumptions, and datasets that will not line up when engineers, architects, or BIM teams pick them up. Every one of those problems is cheaper to prevent in the brief than to discover on site.
How we scope a heritage survey
Our starting point is the end use, not the instrument. We ask what decisions the data has to support: conservation planning, repair design, structural analysis, long term monitoring, or a BIM model for phased works. That answer sets the accuracy, the control strategy, the capture method, and the deliverable format, all referenced against HEAG317.
Where a brief only cites a Level of Record, we translate it into a metric specification before a single scan is taken. It is a short conversation that removes almost all of the risk that shows up later.
The guidance is being brought into line
Historic England is revising HEAG099 to point clearly toward HEAG317 for survey grade work, to remove dated technical content, and to keep the Levels of Record while signposting when professional metric survey is genuinely needed. It is a welcome move that will make briefs cleaner across the sector. The direction of travel only reinforces good practice that is already available to anyone commissioning today.
A checklist for a watertight brief
- State the end use of the data, since it drives every other decision.
- Set the accuracy and control requirement, and reference HEAG317 for metric outputs.
- Confirm whether the model must be georeferenced to the National Grid.
- Define the deliverables: 2D drawings, 3D model, orthophotos, or Scan to BIM at a stated level of detail.
- Specify archive formats and metadata so the record stays usable for future phases.
Get those five right and the Level of Record looks after itself.
Planning a measured survey of a listed or historic building? Our team can turn your recording requirement into a precise, HEAG317-aligned specification. Learn more about our measured building survey service, or get a quote below.
