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The role of building flood resilience within flood risk management Andrew Tagg Principal Engineer Andrew Tagg Principal Engineer.

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Presentation on theme: "The role of building flood resilience within flood risk management Andrew Tagg Principal Engineer Andrew Tagg Principal Engineer."— Presentation transcript:

1 The role of building flood resilience within flood risk management Andrew Tagg Principal Engineer Andrew Tagg Principal Engineer

2 Page 2 © HR Wallingford October, 2014 Outline Overview and definition of resistance / resilience Research basis for new guidance Guidance overview Example of resilient home Future developments

3 Page 3 © HR Wallingford October, 2014 Evolution of approach to floods “Act of God” Accept the vagaries of nature Man against nature Flood defence, control or management Recognise social and environmental dimensions “Living with rivers” Flood risk management A portfolio of policies and actions “Room for the river” (NL, 2000) “Making Space for Water” (UK, 2004) New EU Directive (2007)

4 Page 4 © HR Wallingford October, 2014 Flood Risk Management Practice Post-flood measures Flood event measures Real time risk management Pre-flood measures Preventive risk management Forecasting and warning, reservoir control, evacuation, rescue, etc. Spatial planning, contingency plans, flood defence (mitigation) measures, insurance, preparedness, etc. Relief, clean-up, reconstruction, regeneration, etc.

5 Page 5 © HR Wallingford October, 2014 Hierarchy of flood mitigation approaches Definitions Flood avoidance -constructing the building in such a way that it avoids being flooded, e.g. by raising it above flood level Flood resistant -constructing the building to prevent flood water entering the building or damaging its fabric. This has the same meaning as flood proof Flood resilient -constructing the building in such a way that minimises water ingress and promotes fast drying and easy cleaning, and does not cause any permanent damage Flood repairable -constructing the building in such a way that although flood water enters the building, elements that are damaged by flood water can be easily repaired or replaced

6 Page 6 © HR Wallingford October, 2014 Research/responses for flood mitigation Flood avoidance -PPS25 and use of Flood Risk Assessments to determine flood risk and inform design Flood resistant -testing of flood protection products via kitemark scheme (to address doorways and other openings) Flood resilient -recent project to address other ‘weak points’ in walls, floors, joints Flood repairable -wide experience from flood repair industry (‘PAS64’, ‘Standards for repair’, ‘Repairing flooded buildings’)

7 Page 7 © HR Wallingford October, 2014 Recent project (1) ‘Improving the flood resilience of buildings through improved materials, methods and details’ Funders DCLG & Defra / Environment Agency with: –NHBC –Scottish Building Standards Agency –Council of Mortgage Lenders –Concrete Block Association –CIRIA Core members

8 Page 8 © HR Wallingford October, 2014 Recent project (2) Consortium CIRIA HR Wallingford Leeds Metropolitan University WRc Waterman Burrow Crocker Timeframe January 2005 to February 2007 Contributes to ‘Making Space for Water’ (Defra)

9 Page 9 © HR Wallingford October, 2014 Resilience – main issues Flood resilience Limiting the damage Reducing time to re-occupy Health & safety issues – stress and the disruption to normal lifestyle Cost of repairs (Promoted by insurers) Outcomes A guidance document for key stakeholders Methodology to incorporate methods and techniques into the Building Regulations

10 Page 10 © HR Wallingford October, 2014 WP2 – Review of existing knowledge Reviewed experience and evidence from around the world Very difficult to provide total flood resistance Much of existing knowledge based on expert advice, assumptions and extrapolations The advice is in the main derived from experience and a common sense approach General lack of scientific experimental data Little published scientific research into the performance of buildings and construction materials in floods, with only limited attempts to collect and analyse experiential data

11 Page 11 © HR Wallingford October, 2014 WP 6 (Collation & analysis of post-flood data) Many interviews with key groups/individuals involved in flood repair industry Liaison with other initiatives (e.g. flood resilient house built as part of FLOWS project) Review of new documents (PAS69, ‘Repair of flooded buildings’) Analysis of drying data Largely confirms findings of WP2 review Lack of hard evidence Lack of agreement on definition of resilience

12 Page 12 © HR Wallingford October, 2014 WP5 – Laboratory tests Testing programme: Stage 1 – Building materials Stage 2 – Walls Stage 3 – Floors Stage 4 – Promising / Innovative materials

13 Page 13 © HR Wallingford October, 2014 WP5 – Laboratory tests of building materials Test procedure (mimicking flood conditions) Two phases: - Wetting phase: up to 4 days (48 hours) ; testing units are exposed to still flood water 1m deep - Drying phase: 7 days (168 hours); test units allowed to dry naturally under laboratory ambient conditions

14 Page 14 © HR Wallingford October, 2014 Elements tested

15 Page 15 © HR Wallingford October, 2014 Test results Hand-made brick Seepage through Hand-made brick

16 Page 16 © HR Wallingford October, 2014 Stage 2 - Testing of walls Test rig – two identical test rigs

17 Page 17 © HR Wallingford October, 2014 Test results – illustrative examples Wall ME1 (Eng Bricks on external face and Concrete blocks on internal face) during wet test Plaster board

18 Page 18 © HR Wallingford October, 2014 Flood resilience characteristics Water penetration – the seepage through the material (different from “water absorption”) Drying ability – the capability to regain the original moisture condition Retention of pre-flood dimensions, integrity – the lack of deformation or change in form or appearance of the material

19 Page 19 © HR Wallingford October, 2014 Summary information for Guidance * Resilience characteristics are related to the testing carried out and exclude aspects such as ability to withstand freeze/thaw cycles, cleanability and mould growth

20 Page 20 © HR Wallingford October, 2014 New Guidance May 2007 Launched by Minister

21 Page 21 © HR Wallingford October, 2014

22 Page 22 © HR Wallingford October, 2014 Proposed changes to Building Regulations New requirement in Part C* - Resistance to the effects of flooding: An FRA/FCA – mirroring requirements in PPS 25/TAN 15 Requirement to incorporate reasonable measures to mitigate the effects of flooding Adequate means of refuge/escape Safe during floods without increasing risk to emergency services * Site preparation and resistance to contaminants

23 Page 23 © HR Wallingford October, 2014 Closing the loop between Planning and B. Regs. Proposals to B Regs – expected to be implemented in 2008/09 – aim to close the loop between: Planning system - key responsibility to determine whether flood effect mitigation is required Building control - responsible for its application In practice, proof of compliance to amended Part C to be sent to LPA prior to commencement of building work

24 Page 24 © HR Wallingford October, 2014 Resilient House (1)

25 Page 25 © HR Wallingford October, 2014 Resilient House (2)

26 Page 26 © HR Wallingford October, 2014 Concluding remarks Await amendment to Building Regs. – will it happen? Recent project on ‘encouraging uptake of resilience’ Pilot studies on resilience measures – update end May Has new Guidance being used? Clear benefits from resilience, BUT - Needs incorporating into policy - Uptake for existing properties would provide greater benefits


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