KARL HARRISON MPGCA MIET MAPL
RICS Expert Witness Certified (May 2025)
If you are dealing with a failed deck, roof terrace or balcony installation and need an independent, evidence-led opinion, I can help. I undertake measured site inspections, identify the most likely cause(s) of failure, define the extent of the defect(s), set out an appropriate remedial scope (repair vs replace), and provide a reasonable cost quantum based on prevailing market rates.
I am instructed by solicitors and private clients and produce reports suitable for dispute resolution, including CPR Part 35-compliant reporting where applicable.
What I cover
- Failed decking systems (timber and composite)
- Defective workmanship vs material defect considerations
- Falls, drainage and surface water issues affecting external deck/terrace build-ups
- Fixings, subframe detailing, ventilation, moisture management and installation compliance
- Roof terraces and balcony decking (including load, movement observations where visible/accessible)
- Associated external works where relevant (thresholds, edging/restraints, steps, balustrades, finishes)
Report outputs (as required)
- Independent inspection reports, SJE and statements of opinion
- CPR Part 35 reports (civil matters where instructed appropriately)
- Supplementary reports (multiple areas / multiple owners)
- Scope of works recommendations (repair vs replace, outline specification and compliance references)
- Quantum / costings (materials, labour, access, waste, making good, preliminaries, OH&P)
Typical report content
- Cause (workmanship, material defect, design/detailing, maintenance/misuse, and contributing factors)
- Extent (what is affected / what is not affected)
- Urgent safety risks (immediate hazards and interim risk mitigation if required)
- Remedial scope (options, method outline and relevant standards/guidance where applicable)
- Cost quantum (reasonable market rates and allowances for access/logistics and making good)
- Photographic schedule (referenced images aligned to observations)
Professional standing
- Qualified – Royal Institute of Chartered Surveyors in Independent Expert Witness
- Accredited Member — Association of Professional Landscapers (APL)
- Fellow Member — Professional Garden Consultants Association (PGCA)
- Full Member — Institution of Engineering & Technology (IET)
- Graduate – City and Guilds Institute (GCGI)
Areas covered
UK-wide by arrangement, with regular coverage across Buckinghamshire, Hertfordshire, London, Berkshire and Oxfordshire.
Karl Harrison
Karl Harrison is a Landscape consultant and covers all elements of garden construction and landscaping disputes. He has been in the industry as a professional since 2003
Chat 07581 193034
