Insight to Structural Waterproofing


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When constructing a building, waterproofing is a major factor. Learn why and how to go about it

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Insight to Structural Waterproofing

  1. 1. A Guide to Structural Waterproofing Part One Waterproofing Protection For Below Ground Structures1 © 2012 W. R. Grace & Co | Benjamin J. Brooks
  2. 2. Table of Contents • Grace Around The World • Reference Material • Waterproofing Strategies • System Selection • Detailing & Workmanship • Summary • Questions2 © 2012 W.R. Grace & Co.
  3. 3. Grace Around the World Global Headquarters UK Headquarters Columbia, MD, USA Slough, Berkshire. 52 4 5 4 2 2 2 2 2 Highlights Global headquarters • Operations in Over 40 Countries Key offices • Leading specialty chemical and materials company Regional headquarters 93 manufacturing sites • Founded in 1854 44 R&D/Tech Service sites • Approximately 6,000 employees with $3bn turnover3 © 2012 W. R. Grace & Co | Benjamin J. Brooks
  4. 4. STRUCTURAL WATERPROOFINGReference Material BS8102:2009: Code Institution of Civil of Practice for Engineers (ICE): Protection of Below Reducing the Risk Ground Structures of Leaking against. Water from Substructure a the Ground Clients Guide  BS8102 gives recommendations and • An ICE client guide explaining provides guidance of methods of dealing substructure waterproofing issues and the with and preventing the entry of water risks associated with waterproofing from surrounding ground into a structure below ground level.4 © 2012 W. R. Grace & Co.
  5. 5. WaterproofingSTRUCTURAL WATERPROOFINGThe Waterproofing Strategies Strategy • Design Flow Chart • Design Team • Clients Requirements • Desk Study • Risk Assessment • Consequences of Failure5 © 2012 W. R. Grace & Co.
  6. 6. STRUCTURAL WATERPROOFING Initial InformationDesign Flow Chart Design Philosophy •Design Team Site Evaluation •Desk Study •Risk Assessment Assess the risks from •Water table Classification Review of Structure external environment, then •Type (e.g.. New or Existing?) •Intended use adopt a waterproofing •Foundation form and design •Construction Methodology strategy capable of achieving client’s requirements Structural Design Considerations • Early inclusion of waterproofing Selection of type A, B or C specialist Waterproofing Protection • Clear understanding of clients Is combined Protection Necessary? requirements and expectations Has Buildability been considered? No • Develop strategy and select Has repairability been addressed? waterproofing system as part of overall Yes robust Solution6 © 2012 W. R. Grace & Co.
  7. 7. STRUCTURAL WATERPROOFING A waterproofingDesign Team specialist should be included as part of the design team so that an integrated waterproofing solution is created. The waterproofing specialist should: • Be suitably experienced; • Be capable of devising solutions that accommodate various projects constraints and needs; • Provide the design team with Note: The waterproofing specialist could be information and guidance that the manufacturer or material supplier, assists with and influences the provided that the manufacturer/supplier design, installation and future has the relevant expertise maintenance of the waterproofed BS8102:2009 clause 4.2 structure7 © 2012 W. R. Grace & Co.
  8. 8. STRUCTURAL WATERPROOFINGClients Requirements • Does the client understand the difference between wet; damp; dry? • Have the costs associated with achieving a DRY basement been considered? • What are the consequences of failure? • Has the future use of the building been discussed?8 © 2012 W. R. Grace & Co | Benjamin J. Brooks
  9. 9. STRUCTURAL WATERPROOFINGSite Evaluation - Desk Study • Hydrostatic head, water table and perched water table • Local topography, soil type, contaminates, gas • Missing information obtained by physical site investigation BS8102:2009 5.1.1 • Historical information9 © 2012 W. R. Grace & Co | Benjamin J. Brooks
  10. 10. STRUCTURAL WATERPROOFINGSite Evaluation – Risk Assessment • Long term water pressures • Affects of surface water infiltration • Use of external drainage • Effects of climate change, burst water mains sewers. • Effects of drainage on existing neighbouring structures • Effects of gas or contaminates BS8102:2009 5.1.210 © 2012 W. R. Grace & Co | Benjamin J. Brooks
  11. 11. STRUCTURAL WATERPROOFINGBS8102:2009 Water Table Classification High Permanently above underside of the base slab Variable Where the water table fluctuates Low Permanently below underside of the base slab in free draining strata. For variable or non free draining strata the classification is considered as high11 © 2012 W. R. Grace & Co | Benjamin J. Brooks
  12. 12. STRUCTURAL WATERPROOFINGPotential Water Ingress Potential Water Ingress • Ingress may occur from more sources than just groundwater.12 © 2012 W. R. Grace & Co.
  13. 13. STRUCTURAL WATERPROOFINGConsequences of Failure Consequences of Failure • Disputes costs, legal fees • Private or public property damage liability • Endangerment of building operative or public from damage to electrical equipment • Damage to archives, stored goods or plant • Loss of rent • Reduction in value of property • Damage to reputation of landlord/developer • Facility, business disruption • Lack of access/utility of basement areas • Costs of remedial work and operational delays13 © 2012 W. R. Grace & Co.
  14. 14. STRUCTURAL WATERPROOFINGWaterproofing System Selection Waterproofing System Selection • BS 8102:2009 Basement Grades • BS 8102:2009 Protection Types • Water Migration • Guidance on Combined Systems14 © 2012 W. R. Grace & Co.
  15. 15. STRUCTURAL WATERPROOFINGBasement Grades - BS 8102: 2009 Wet Grade 1 Basic Utility Car parking ; plant rooms (excluding electrical equipment); workshops Damp Grade 2 Better Utility Plant Rooms and Workshops requiring drier environment than grade1 Dry Grade 3 Habitable Ventilated residential and commercial areas inc. offices, restaurants; leisure centers15 © 2012 W. R. Grace & Co | Benjamin J. Brooks
  16. 16. STRUCTURAL WATERPROOFINGProtection Types Barrier A Physical Barrier.  Fully Bonded Membranes, Loose Laid Geosynthetic Clay Liners  Cementitious Renders, Liquid Waterproofing Systems Structural Integral B Protection by Design  Admixures, Controlled Crack Width Design  Sheet Pilling (may need further protection) Drained Protection C Cavity Drain  Preformed Cavity formers  Designed Open Cavity Apart from managing the risks, it is important to understand the waterproofing options available; each method will have cost and space implications for the basement scheme (ICE) REDUCING THE RISK OF LEAKING SUBSTRUCTURE A CLIENTS GUIDE16 © 2012 W. R. Grace & Co | Benjamin J. Brooks
  17. 17. STRUCTURAL WATERPROOFINGTypical Type A SolutionsTypical Type A Solutions Pre-Applied Bonded Bonded Sheet Cementitious Membranes Membranes Coatings  Applied prior to placing of  Full & intimate bond  Designed for negative structural concrete vertically water pressure  Full and intimate bond  Eliminates water migration  Eliminates water  Eliminates water migration vertically migration vertically vertically & horizontally  Some can be suitable as  Good as solution to  Suitable for alkaline soil gas protection complex details conditions  Some can be used in  Ideal as remedial solution  Unaffected by wet dry alkaline soil conditions cycling17 © 2012 W. R. Grace & Co | Benjamin J. Brooks
  18. 18. STRUCTURAL WATERPROOFINGWater Migration18 © 2012 W. R. Grace & Co.
  19. 19. STRUCTURAL WATERPROOFINGTypical Type A Solutions Typical Type A Solutions Mastic Asphalt Mechanical Key Bentonite Carpets Membranes  Must be applied in three  Mechanical key to concrete  Mechanical key to coats  Does not resist water concrete Does not resist  Dated technology that migration water migration requires heat  Not suitable for alkaline  Can become brittle with ground age  Wet/dry cycling?19 © 2012 W. R. Grace & Co | Benjamin J. Brooks
  20. 20. STRUCTURAL WATERPROOFINGTypical Type B SolutionsTypical Type B Solutions Structural Design Concrete Design with Sheet Piled wall Admixture  Controlled crack width  Requires proper curing of  Additional protection may the in-situ concrete. be needed  Additional protection may be needed  No requirement for vapour  Relies on workmanship barrier  Can be cost prohibitive due to steel content  QSRMC/BSI accredited  Can be used as part of a ready-mix supplier. redundant post injection  Should be considered as system. part of a system that includes water stops20 © 2012 W. R. Grace & Co | Benjamin J. Brooks
  21. 21. STRUCTURAL WATERPROOFINGTypical Type C Solutions Drained Cavity Open Cavity Design Installed internally after Installed after basement construction of basement. construction No hydrostatic pressure on Does not prevent vapour sheets designed more transmission minor seepage.21 © 2012 W. R. Grace & Co | Benjamin J. Brooks
  22. 22. STRUCTURAL WATERPROOFINGCombined Solutions Use of Combined Protection Systems Reduces Risk • Consider combining multiple systems of waterproofing where: • Assessed external risks are high • Consequences of failure to achieve desired internal environment are high.22 © 2012 W. R. Grace & Co | Benjamin J. Brooks
  23. 23. STRUCTURAL WATERPROOFINGDetailing Detailing - Adopt a Simple Approach • Involve the waterproofing specialist for advice • Ensure continuity with above ground DPC/building envelope. • Consider buildability and order of works.23 © 2012 W. R. Grace & Co.
  24. 24. STRUCTURAL WATERPROOFING QualityWorkmanship Waterproofing Demands Teamwork • Potential risks identified in the waterproofing strategy should be understood by the whole team. • Changes to sequence of works will have a major impact on waterproofing integrity. • Ensure the contractor has the prerequisite experience to install the chosen system24 © 2012 W. R. Grace & Co | Benjamin J. Brooks
  25. 25. STRUCTURAL WATERPROOFING Basement Grades - BS8102Systems Summary Grade 1 - Wet Grade 2 - Damp Grade 3 – Dry Protection Types Type A – Barrier Type B – Structural Integral Type C – Drained Cavity • Look for Materials that limit water migration. • Consider combined systems where the risks & consequences of failure are high25 © 2012 W.R. Grace & Co.
  26. 26. STRUCTURAL WATERPROOFINGSummary System Choice Substructure Protection Design Workmanship Successful protection Waterproofing Protection For Below Ground Structures relies on these three elements.26 © 2012 W. R. Grace & Co | Benjamin J. Brooks
  27. 27. STRUCTURAL WATERPROOFING Any Questions? Thank you for your attention & participationQuestions 27 © 2012 W. R. Grace & Co.
  28. 28. Contact Information For additional information, please visit or contact: preprufe@grace.com28 © 2012 W. R. Grace & Co | Benjamin J. Brooks