Drawing and survey information

Survey drawings and data are produced using professional surveying equipment and methodologies in accordance with industry best practice. However, all surveys are subject to inherent limitations, and users of the information must understand the basis and constraints of the data provided.

1. Coordinate System and Survey Control

1.1 Horizontal Coordinate System

Unless stated otherwise, surveys are referenced to the Ordnance Survey National Grid (OSGB36) using Global Navigation Satellite Systems (GNSS) observations and corrections from the Ordnance Survey Active Network (OS Net).

Transformations between global GNSS coordinates and OSGB36 are applied using OSTN15 and OSGM15 models.

Where required, a local site grid may be established to simplify drawing orientation or site setting out.

A local grid does not necessarily represent true Ordnance Survey grid coordinates.

1.2 Vertical Datum

Unless otherwise stated, levels are referenced to Ordnance Datum Newlyn (ODN) via GNSS observations, benchmarks, or known control points.

Where a local height datum is used, this will be clearly stated in the survey documentation.

1.3 Survey Control Points

Survey control points may be established across the site to provide a stable reference for future setting out and verification.

A Survey Control / Station Table may be issued with coordinates, descriptions, and photographs of control points.

Users should refer to this table when establishing site control for design or construction.

2. Survey Accuracy and Tolerances

Survey data is collected using professional-grade equipment including GNSS receivers, total stations, laser scanners, and photogrammetry systems.

Typical accuracy ranges (indicative only):

Topographical Survey

• Horizontal: ±10–30 mm (dependent on method and site conditions)
• Vertical: ±10–20 mm

Measured Building Survey (MBS)

• Internal dimensions: typically ±5–15 mm
• Structural outlines and features subject to access and visibility

Laser Scanning / 3D Models

• Point cloud accuracy dependent on scanner specification, registration quality, and site geometry
• Typical registration error: ±5–15 mm

Drone Survey / Photogrammetry

• Ground sample distance and accuracy dependent on flight height, control points, and environmental conditions

Actual accuracy will vary based on site conditions, visibility, geometry, and survey method.

3. Survey Limitations

All surveys are subject to limitations, including but not limited to:

3.1 Access Restrictions

• Areas that were inaccessible, locked, unsafe, or obstructed at the time of survey may not be captured.
• Parked vehicles, vegetation, temporary structures, and site activity may obscure features.

3.2 Hidden and Buried Features

• Surveys are based on visible and accessible features only unless otherwise stated.
• No responsibility is accepted for concealed, buried, or internal features not visible at the time of survey.

3.3 Utilities and Drainage

• Underground services and drainage features shown on drawings are interpreted from surface evidence unless confirmed by utility detection surveys or intrusive investigation.
• The absence of utilities on drawings does not indicate their absence on site.

3.4 Tolerances and Interpretation

• Survey data is subject to measurement tolerances, instrument limitations, and interpretation.
• Small discrepancies between survey data and actual site conditions may occur and should be expected.

4. Use of Survey Drawings and Data

4.1 Intended Use

Survey drawings and deliverables are issued solely for the purpose stated in the contract and for the use of the named client.

They are not intended for use by third parties without written consent from IG Surveys Ltd.

4.2 Third-Party Reliance

No third party may rely on survey drawings, reports, or data without a formal reliance letter issued by IG Surveys Ltd.

Reliance may be subject to additional fees and limitations of liability.

4.3 Verification on Site

All dimensions and levels must be checked on site prior to:

• Design
• Setting out
• Construction
• Fabrication

Survey data should not be used as the sole basis for critical construction without verification.

5. Intellectual Property and Copyright

All drawings, reports, point clouds, models, photographs, and digital data produced by IG Surveys Ltd remain the intellectual property of IG Surveys Ltd.

The client is granted a non-exclusive licence to use the deliverables for the project for which they were produced.

Deliverables may not be copied, modified, distributed, or relied upon by third parties without written permission.

6. Laser Scanning, 3D Models and Digital Data

Where 3D laser scanning, mobile mapping, or photogrammetry has been undertaken:

• High-definition imagery may capture text, objects, and confidential materials within the surveyed environment.
• Data may be hosted on secure cloud platforms such as NIRA, Autodesk, or equivalent.
• Users must ensure appropriate permissions have been obtained for data capture and sharing.

IG Surveys Ltd may remove or redact sensitive content upon request where reasonably practicable.

7. Drone Surveys

Drone operations are conducted in accordance with UK Civil Aviation Authority (CAA) regulations.

Drone surveys are subject to:

• Airspace restrictions
• Weather conditions
• Site safety constraints
• Regulatory approvals

Delays, omissions, or rescheduling due to regulatory or safety constraints are not the responsibility of IG Surveys Ltd.

8. Professional Indemnity and Liability

IG Surveys Ltd holds Professional Indemnity Insurance appropriate to the services provided.

To the maximum extent permitted by law:

• The total liability of IG Surveys Ltd is limited to the fee paid for the Services, unless otherwise agreed in writing.
• IG Surveys Ltd shall not be liable for indirect or consequential losses, including loss of profit, business, or revenue.

Nothing in these notes limits liability for death, personal injury, fraud, or statutory consumer rights.

9. Data Retention and Quality Assurance

Survey data may be retained by IG Surveys Ltd for:

• Quality assurance
• Internal audit
• Legal and contractual purposes

Anonymised survey outputs may be used for marketing, training, or portfolio purposes unless the client requests otherwise in writing.

10. Contact and Further Information

For questions regarding survey data, deliverables, or additional services, please contact:

IG Surveys Ltd
Email: info@igsurveys.co.uk
Website: www.igsurveys.co.uk

11. Disclaimer for Design and Construction

Survey drawings and data are not design documents and must not be used as a substitute for engineering or architectural design.

IG Surveys Ltd does not accept responsibility for design decisions, structural performance, or construction outcomes based on survey information.