GPR survey for chimney flue mapping in London home

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Delivering expert underground utility and utility mapping surveys

Ground Penetrating Radar survey conducted to identify chimney flues within the walls of a London building

Location: Brompton Square, London SW3 2AD

Project description

Red Laser was appointed by AR Architecture to carry out a non-invasive Ground Penetrating Radar (GPR) survey at a listed property in Brompton Square, London. The objective was to locate and map historic chimney flues within two nominated internal walls — from the lower ground to the fourth floor — without damaging the original structure.

Equipment used

Model: Proceq GP8000 Ground Penetrating Radar
Technology: Stepped-frequency continuous-wave (SFCW)
Frequency range: 200–4000 MHz
Penetration depth: Up to 150 cm
Software: Proceq analysis suite for data interpretation and visualisation

Methodology

Horizontal scan lines set at 0.3m intervals in a structured grid
Real-time data acquisition with on-site calibration using a standard relative permittivity (3.5 for masonry)
Results compiled and overlaid onto client-provided CAD drawings

Challenges faced

Access limitations: Pipes, electric boxes, and a boiler restricted scanning in certain zones
Moisture: High moisture levels on the lower ground floor affected radar signal clarity

Capturing detailed utility mapping data, our team provides comprehensive insights into underground utilities to support your project

Final CAD output from GPR chimney flue survey, detailing confirmed flues in red, with possible and assumed paths marked in blue and yellow for full subsurface clarity

Solutions & outcomes

Successfully identified multiple chimney flues (marked in red)

Possible and assumed flue positions were also marked (blue and yellow), with inconclusive zones due to stud walls shown in purple

PDelivered two CAD drawing files with flue locations and depth annotations (110mm to 160mm)

Provided clear, accurate, and visually detailed subsurface insights despite environmental limitations

Deliverables

Despite environmental constraints, Red Laser delivered high-precision, non-destructive results. The detailed outputs empowered AR Architecture with clear, actionable insights to support restoration planning and structural decision-making.

GPR survey report (PDF)

Professional interpretation with legend and depth data

Annotated CAD drawings (2 files)

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