Glazing System Remediation Project Brook Van Dalen & Associates - - PowerPoint PPT Presentation

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Glazing System Remediation Project Brook Van Dalen & Associates - - PowerPoint PPT Presentation

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Bank of Canada Headquarters Building, Ottawa Glazing System Remediation Project Brook Van Dalen & Associates Limited Located downtown Ottawa on the block bounded by Wellington Street to the north, Spark Street to the south, Kent Street

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Bank of Canada Headquarters Building, Ottawa

Glazing System Remediation Project

Brook Van Dalen & Associates Limited

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  • Located downtown Ottawa on the block

bounded by Wellington Street to the north, Spark Street to the south, Kent Street to the west and Bank Street to the east

  • The original head office building for the

Bank of Canada was constructed on the site in the 1930’s

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  • In the 1970’s an atrium and two new

towers were designed and constructed to partially enclose the original building

  • Arthur Erickson, the lead design architect,

selected a metal and glass enclosure for the new construction, distinct and widely recognized because of his choice of copper for all the exposed exterior metal components

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  • Exterior appearance of towers and Atrium

is consistent, but actually two different types of glazing systems

  • In addition to use of copper, unique

features of glazing system include:

– Slab to slab glazing units – Triangular profile caps

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Towers

– Most similar to conventional curtain wall – Primary vertical mullions ‘continuous’ with stack joints at each slab level – Mullions anchored to concrete floor slabs – Vertical plates and caps do not run through spandrel region – Very narrow module (2.5’) – Very short spandrel height – 12th floor incorporates sloped glazing system

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Atrium

  • Most similar to conventional window wall
  • Panels of framing set between floor levels,

but outside of structure

  • Horizontal rails anchored to structural steel

beams

  • Wider module (5’)
  • Very short spandrel height
  • No sloped glazing
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  • Original system design incorporated

insulating glass units with reflective coating, air fill

  • Spandrel assemblies included copper

panel, 25 mm insulation, galvanized pan

  • Coupled with height of glass and amount
  • f framing used, system very poor with

respect to thermal performance

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  • All systems were intended to be drained
  • Plates incorporated drainage slots, caps

did not

  • Caps on horizontal rails intended to drain

into caps on vertical mullions

  • Drainage to exterior intended through gap

at base of each vertical mullion cap, on top side of horizontal cap

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So…….why are we here today to talk about remediation of the glazing system(s)???

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  • Prior to the remediation project, a study of

the glazing system was commissioned by the Bank in response to three primary concerns:

– Detracting appearance of caps on exterior wall (deformation and need for mechanical fastening) – Water leakage – Rate of IG unit failure

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The results of the preliminary study caused the Bank to initiate the

Exterior Glazing System Remediation Project

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Key Success Factors

  • Resolve and improve the technical

performance efficiently

  • Minimize disruption to the occupants
  • Respect the integrity of the Architecture
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Design/Build for a Curtain Wall Remediation?!!

  • A unique contract for a unique challenge
  • A single obligation of result
  • The strength of a team from conception to

completion

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Remediation Project Team

  • BANK OF CANADA
  • VANBOTS CONSTRUCTION CORPORATION
  • FERGUSON NEUDORF GLASS INC.
  • BROOK VAN DALEN & ASSOCIATES LIMITED
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Technical Challenges

  • Understand cause and develop solution for each
  • f the three primary concerns:

– Detracting appearance of caps on exterior wall (deformation and need for mechanical fastening) – Water leakage – Rate of IG unit failure

  • Maintain (improve) appearance of wall, including

preservation of patina on any new copper

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Detracting Appearance of Caps on Exterior Wall

  • Original system used a dress cap of

copper applied over an extruded aluminum snap cap

  • Poor combination of materials to have in

contact, in light of high potential for galvanic reaction

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Galvanic Series of Metals

  • MAGNESIUM

MAGNESIUM ALLOYS ZINC ALUMINUM 5052, 3004, 3003, 1100, 6053 CADMIUM ALUMINUM 2117, 2017, 2024 MILD STEEL (1018), WROUGHT IRON CAST IRON, LOW ALLOY HIGH STRENGTH STEEL CHROME IRON (ACTIVE) STAINLESS STEEL, 430 SERIES (ACTIVE) 302, 303, 321, 347, 410,416, STAINLESS STEEL (ACTIVE) NI - RESIST 316, 317, STAINLESS STEEL (ACTIVE) CARPENTER 20CB-3 STAINLESS (ACTIVE) ALUMINUM BRONZE (CA 687) HASTELLOY C (ACTIVE) INCONEL 625 (ACTIVE) TITANIUM (ACTIVE) LEAD - TIN SOLDERS LEAD TIN INCONEL 600 (ACTIVE) NICKEL (ACTIVE) 60 NI-15 CR (ACTIVE) 80 NI-20 CR (ACTIVE) HASTELLOY B (ACTIVE) BRASSES COPPER (CA102) MANGANESE BRONZE (CA 675), TIN BRONZE (CA903, 905) SILICONE BRONZE NICKEL SILVER COPPER - NICKEL ALLOY 90-10 COPPER - NICKEL ALLOY 80-20 430 STAINLESS STEEL NICKEL, ALUMINUM, BRONZE (CA 630, 632) MONEL 400, K500 SILVER SOLDER NICKEL (PASSIVE) 60 NI- 15 CR (PASSIVE) INCONEL 600 (PASSIVE) 80 NI- 20 CR (PASSIVE) CHROME IRON (PASSIVE) 302, 303, 304, 321, 347, STAINLESS STEEL (PASSIVE) 316, 317, STAINLESS STEEL (PASSIVE) CARPENTER 20 CB-3 STAINLESS (PASSIVE), INCOLOY 825NICKEL - MOLYBDEUM - CHROMIUM - IRON ALLOY (PASSIVE) SILVER TITANIUM (PASS.) HASTELLOY C & C276 (PASSIVE), INCONEL 625(PASS.) GRAPHITE ZIRCONIUM GOLD PLATINUM

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Remedial Work Requirements

  • Eliminate direct copper/aluminum contact
  • Replace all plates and caps
  • Replace all glass units
  • Reduce water passage through outer face
  • f system
  • Renew inner seals of system for air and

water tightness

  • Provide clear drainage for glazing and

spandrel cavities

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Remediation Procedures

1. Strip and discard all copper dress caps 2. Strip and discard all aluminum pressure plates 3. Strip and STORE all copper spandrel panels, discard mirror column cover panels 4. Strip and discard all spandrel insulation and backpans 5. Verify condition of anchors and take necessary remedial action

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Remediation Procedures (cont’d)

  • 6. Reseal expansion joints in vertical

mullions

  • 7. Install new galvanized spandrel

backpans,properly sealed to framing

  • 8. Install new corner blocks at framing

intersections, renew joinery seals

  • 9. Remove and discard all IG units

10.Install new IG units

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New Glass Units

  • New glass product selected to match, as

closely as possible, reflectivity of original glass

  • Also incorporated:

– low-’E’ coating – argon gas fill – heat strengthening for typical units – laminated glass at lowest levels and at 12th floor sloped section

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*>179L *<0L 20 40 60 80 100 120 140 160

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Glazing Challenges

  • Essential to maintain minimum dimension for drainage

cavity around new units while maintaining adequate bite

  • Many of Atrium framing openings out of square
  • All glass ordered for ‘typical’ opening size, which often

did not accept glass with appropriate clearance

  • Checklist of remedial work to address non-standard
  • penings included:

– Temporarily releasing panel anchors, jacking framing and refastening anchors – Cutting off framing nosing and applying new nosing extrusion ‘off-centre’ on framing – Installing new interior stops and structurally glazing one or more edges of new IG units

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Remediation Procedures (cont’d)

11.Install new spandrel insulation and STORED copper spandrel panels 12.Install new pressure plates

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Elimination of Direct Copper/Aluminum Contact

  • Eight new pressure plate profiles designed

to match width of original plates, profile of

  • riginal caps
  • Plates designed to receive new copper

caps

  • Selected pultruded fiberglass as new plate

material

  • Iterations required to optimize design
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Thermal Impact of New Plates

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Remediation Procedures (cont’d)

13. Install new copper caps

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New Copper Caps

  • Eight 8 new caps designed to pair with new plates
  • Step #1 – create break form samples based on initial

production samples of plate

  • Step #2 – iterate combinations of gauge, temper and

profile with break form to obtain balance of fit, impact resistance and ‘workability’

  • Step #3 – produce roll form to mimic selected break form

sample

  • Step #4 – check fit of initial roll form product ON SITE
  • Step #5 – produce required lengths of cap with mitres,

weep slots, etc.

  • Step #6 – apply patina to finished caps
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Patina Challenge

  • Patina of original copper was applied over two years with unknown chemicals and

processes, except that process known to include sun-drying in local field

  • Metallurgical analysis of the original patina revealed:

– Amine groups present are indicative of horse urine pre-treatment – No sulphur found, often atmospheric cause of patina formation – Primary components in patina include chloride (salts or hydrochloric acid) and aluminum silicates – Final patina coated with acrylic lacquer (hence limited atmospheric impact)

  • Many iterations of candidate new patina were conducted using various chemical

combinations (10) in attempt to match original colour range

  • Various techniques for application of chemicals tried in attempt to match original

‘streaking’ of patina

  • Final selection results from another proprietary process
  • Basic chemical families are identified to confirm health & safety respected
  • Process known to include dipping formed copper in a chemical vat followed by two or

three brush applications of chemicals, all combined with multiple passes of baking in a custom oven

  • Details of patina coating not revealed to prevent reverse engineering
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Remediation Procedures (cont’d)

  • Entire building remained occupied throughout

the work

  • Stages installed around full perimeter of each

tower, one at a time

  • Full tower-floor of IG units changed in one night

shift

  • All remaining remedial work on towers also

performed during night shifts

  • Atrium remedial work conducted during the day
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Resetting the Life Cycle Clock

  • After 26 years of service, glazing system has been completely

rehabilitated

  • Anchorage upgraded where necessary
  • Interior seals renewed
  • Higher performance glass units installed
  • Internal drainage reinstated
  • Exterior seals renewed
  • Copper/aluminum contact eliminated
  • New, corrosion resistant, low conductivity plates installed
  • New caps installed to reinstate original appearance
  • Rehabilitated system sure to provide improved performance over

another (extended) service cycle

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THE END