Case studies Patrick Isaacs BSc(Hons) CEng MICE ACILA National Engineering Manager Cunningham Lindsey
Process Inspection Investigation Diagnosis Mitigation Repair
Case study 1 Clay shrinkage Visit 21/07/11 Minor damage to porch London clay area
Case study 1 Date of finalisation? 1. April 2012 2. November 2012 3. November 2011 4. Still ongoing Visit 21/07/11 Minor damage to porch London clay area
Case study 2 - Heave
Case study 2 - Heave Distortion to RWP Large crack at movement joint
Case study 2 - Heave Development built 1993 Pre-construction site investigation confirmed shrinkable clay soils to depth (London Clay) Conceptual design specified piled foundation Detailed design of piles and ground beams not available Damage commenced 2005/6. Claim notified 2007.
Case study 2 - Heave Site investigation confirms adequate construction Integrity test satisfactory Clay and (dead) roots to 5m
Movement Case study 2 - Heave Level monitoring continual upwards movement 18 16 14 12 Series1 Series2 10 8 6 4 2 0 Series3 Series4 Series5 Series6 Series7 Series8 Series9 Date
Case study 2 Heave The problems. Liability?
Case study 2 Heave The problems. Policy excludes Damage or consequential loss caused by or consisting of defective design or workmanship or the use of defective materials What was the claim outcome? 1.Repudiate for defective design 2.Repudiate for defective workmanship 3.Repudiate for defective materials 4.Accept liability
Case study 2 Heave The problems. Liability? No mitigation and ongoing movement? Lasting repair? Use/occupancy of building? Costs?
Case study 2 - Heave Question - What is the solution? 1. Demolish and rebuild 2. Cash settlement 3. Heave relief scheme 4. Wait for heave to dissipate and then repair
Case study 2 - Heave Heave relief scheme adopted Level monitoring identified which sections of building suffering ongoing heave Excavations to remove heaving clay from contact with foundation ie introduce void.
Case study 2 - Heave Beam and block floor lifted to gain access to subfloor void Excavation beneath ground beam
Case study 2 - Heave Excavation continuing to form void Existing pile
Case study 2 - Heave Void complete Temporary shuttering
Case study 2 - Heave Backfilling underway
Case study 2 Heave Final reinstatement
Case study 2 - Heave Pilot carried out within one flat initially to confirm viability Main works phased to minimise disruption to residents and staff Pilot commenced in Jan 2011 Practical Completion for final phase achieved Oct 12 Costs c 375,000 plus vat, remedial piled underpinning estimated at 1.5M (and flats would need to be vacant)
Case study 2 - Heave Good example of collaborative approach between Insurer, policyholder and adjuster Clear lines of communication, regular site meetings Not without problems, but these dealt with quickly and effectively. Win-win - Development remained in use throughout for P/H and Residents Control of spend for Insurer
Case study 3 - Conservatories
Case study 3 - Conservatories Estate built 2001 Conservatory added c2006/7 Claim notified 2009
Case study 3 - Conservatories
Case study 3 - Conservatories Standard domestic policy - Subsidence wording excludes Damage caused by faulty design, materials or workmanship Building regulations do not apply FOS involvement
Case study 3 - Conservatories What was the claim outcome?: 1. Claim declined in accordance with exclusion 2. Claim accepted in part (p/h to fund new foundations) 3. Claim accepted in full Estate built 2001 Conservatory added c2006/7 Claim notified 2009
Case study 3 - Conservatories Same estate, different house Identical conservatory Drain found to be leaking
Case study 3 - Conservatories Does this change things? Wording as before. 1. Claim declined in accordance with exclusion 2. Claim accepted in part (p/h to fund new foundations) 3. Claim accepted in full under subsidence peril 4. Claim accepted in full under EOW peril
Case study 4 - Conservatories
Case study 4 - Conservatories 1950 s semi Conservatory built c1998 Damage commenced summer 2006 Ash tree, 10m distant
Case study 4 - Conservatories Medium shrinkability clay Design foundation depth = 1.40m Actual foundation depth = 0.75m Foundation matches house
Case study 4 - Conservatories What was the claim outcome? Same exclusion. 1. Claim declined in accordance with exclusion 2. Claim accepted in part (p/h to fund new foundation) 3. Claim accepted in full (rebuild conservatory on deeper foundation) 4. Claim accepted in full (superstructure repair only) Medium shrinkability clay Design foundation depth = 1.40m Actual foundation depth = 0.75m Foundation matches house
Summary Onus on Insurer to prove an exclusion Every structure has a design (if only in the mind of the man with the shovel) Design to be judged on criteria in force at time of construction Building Regulations approval can be an irrelevance Is the defective design the proximate cause?
And finally.. Defectively designed foundations do not always need to be replaced.
And finally..