Post on 01-Apr-2018
www.sgh.com
Top Signs of Façade Problems – How to See the Invisible “Vision is the art of seeing things invisible” – Jonathan Swift – NAREIM Home Page Carolyn L. Searls
Outline – How and Where to Look for the Invisible
• I. Top ten signs to look for to detect façade problems • II. The prepurchase survey (and NDT methods) • III. Current problems we’re seeing in building materials
and systems • IV. Current problems we’re seeing in the building
process
I. Top 10 Signs of Façade Problems Water Leaks
10. Deteriorating Sky-facing Surfaces
• Look for – Concrete or masonry parapets without metal copings – Horizontal ledges without waterproofing – Any horizontal surface with deteriorated joints,
waterproofing or paint
9. Efflorescence and Water Stains
• Look for…
8. Rust Stains
8. Rust Stains
• Look for – Orange rust stains – The source of the stains (the steel) – The source of the water
• Expansion of rust product can cause spalls
7. Cracks
• Look for these normal shrinkage cracks
7. Cracks
• Look for these cracks indicative of problems
Thermal and moisture expansion; lack of support
Marble expansion Corrosion
7. Cracks
• Look for these cracks indicative of problems
Corrosion of window lintels
7. Cracks
• Look for these cracks indicative of problems
Seismic
7. Cracks • Cause of the cracks
– The material wants to move but can’t – The material can’t take the stress – Moving or non-moving cracks?
6. Paint Failures
• Look for
5. Deteriorated Mortar Joints
• Look for – Missing mortar, holes in mortar joints – Cracks in mortar joints – Separations between mortar and masonry units – Underlying causes
4. Deteriorated Sealant Joints
• Look for
Cohesion Failure
Reversion
Adhesion Failure
3. Deterioration of Window Systems
• Look for – Gaps at gasket corners – Hardened or failed
sealants or gaskets – Water streaks down
interior vertical mullions – Wet finishes below
window sill – Wet finishes above
window (from floor above)
– Weep holes caulked over
2. Mold
• Look for – Red, black or green mold – Pink spots visible through vinyl wallpaper
1. Pieces Falling Off
• Look for subtle cracks can indicate delaminated pieces, ready to fall off
• Displaced elements • Out-of-plane elements
1. Pieces Falling Off
The Biggest Problems Occur…
• Where components of a building intersect
II. The Pre-purchase Survey Hoping to Uncover the Invisible
• Review drawings and specs, maintenance records, leak records
• Speak with building managers/engineers, occupants • Visual survey from ground • $$$ - Maintenance and repair costs • Close-up visual survey • NDT • Investigative openings • Water testing or other testing, as required
Pre-purchase survey – Interview
• People who are familiar with the everyday behavior of the building
• Gather data on leaks, cracks, previous repairs or alterations
• Are any drawings available? • Does the building leak every time it rains? Or only when
it is windy? • How long after the rain starts do leaks appear?
After the Visual Survey - Next Steps
• More detailed survey – Larger sample size – Close up inspection – Selective disassembly
• Field and laboratory testing – Appropriate water testing
• Analysis – structural, hygrothermal
• Repair design & budgeting
• Options analysis
Pre-purchase survey
• Benefits of close up inspection
Southwest Museum – Rope Access Condition Survey, Sounding, Petrographic Analysis of Plaster
Pre-purchase survey
• Benefits of inspection openings
Nondestructive Testing
• The value of inspection openings
– Open an area to visually or physically confirm the nondestructive test results (say, from GPR, pachometer, etc.)
• The value of a 2nd nondestructive test method
– If openings are not possible or not valuable, it’s good to have a 2nd method to confirm the results of the 1st
• Test results need to be interpreted (and may take some time)
– Data may be immediately available, but the significance may not
– With any test, understand what the test is really measuring
Your Most Important High Tech Tools
Borescope
Photo credit: Michael Schuller
Photo credit: Michael Schuller
Metal Detectors
• Eddy current induction • Run over surface of masonry to identify metal
reinforcement, anchors • Many versions: pachometer, Ferroscan, Profometer
Ground-Penetrating Radar (GPR)
• Next best thing to physically seeing • Produces a “virtual” picture through data on a screen • Data requires interpretation by a trained operator • Excellent for identifying:
– Location and depth of metal reinforcement – Voids in masonry construction – Presence of grout in CMU cells
Ground-Penetrating Radar
• Generally speaking, GPR can locate position and depth of objects within a medium
RILEM Tubes (or Karsten Tubes, or Stormdry Gauges)
• Compare absorption of different types of masonry or before/after treatment
• Correlation with wind-driven rain
RILEM Tubes
• RILEM Test Method II.4: – Affix tube to substrate with putty – Fill tube with water from top; ensure no leaks through putty – Read water level at regular time intervals (e.g. 5, 10, 15, 20, 30,
60 minutes, depending on material and absorption rate) – Report results on a graph of water volume absorbed vs. time
• How many tests? Where? – Up to the judgment of the design professional
• Test standard describes how to do the test, but not how to interpret the results
Infrared Thermography
• Shows differences in temperature not the location of water
• Requires experienced operator (certified thermographer) • Very fast, can cover large areas easily • Time of day can be important in effectiveness of testing
– Early morning – building surfaces relatively cool – Mid-day – building surfaces are warmest
• Useful for diagnosing: – Voids in masonry (including ungrouted cells) – Changes in construction (window infills, etc.) – Wet areas during water testing – Rising damp
Non-destructive Testing to Locate Internal Conditions
• Infrared Thermography
Infrared Thermography
Measuring Moisture in Building Materials
Impedance Measurement
Pin-type Resistance Meters
Temperature/RH Probes
Wood Condition Assessment - Shangri La
Common Signs of Wood Deterioration
• Signs of Decay – Fruiting bodies – Surface depressions – Staining – Insect Activity
– Checks and splits – Cubical checking – “Spongy” feeling
– Mycelium mats – Rhizomorphs
Wood Condition Assessment - Shangri La
• Signs of Insect Activity – Frass – Earthen tubes – Tunnels in wood – Swarming in spring/fall – Shed wings – Chewing or knocking
sounds
Wood Condition Assessment - Shangri La
Wood Condition Assessment - Shangri La
Species Identification: Shangri La
Wood Condition Assessment - Shangri La Resistograph
Water Testing - Shangri La
• Determine leak paths to diagnose problems and design repairs
Water Testing Spray Rack and Pressure Chamber
• We simulate rain with a calibrated spray rack • We simulate wind using a pressure chamber on interior
and sucking the air out
Water Testing Calibrated Nozzle
• Used to isolate leak paths • As a quick check during construction
III. Current Problems in Existing Building Systems or Where to Look for the Invisible
• Window leaks • Non-drainage EIFS • Cement plaster (stucco) • Thin brick and thin stone veneer • Hardipanel • Flooring failures • Balcony decks • Early 20th century buildings deteriorating
Common Causes of Window Leakage Not Following Manufacturer’s Installation Instructions
• Open head-jamb corner
Confidential material protected pursuant to Evidence Code Sections 1115 et. seq.
Common Causes of Window Leakage Sill/jamb Corners
• Sill/jamb corner is not watertight; jamb drains into wall cavity
• Reason for using sill pan flashing
Confidential material protected pursuant to Evidence Code Sections 1115 et. seq.
Common Causes of Window Leakage Missing or Torn Heel Bead or Inadequate Sill Height
• Leads to overtopping of sill
Common Causes of Window Leakage Gaskets Shrink Away From Window Corners
Common Causes of Window Leakage Discontinuous Gaskets and Sealant at Mulled Windows
• Mulled windows are often problematic
Common Causes of Window Leakage Lack of Flashing or Reverse-lapped Flashing
– Incomplete integration of Tyvek with window assemblies
Common Causes of Window Leakage Improper Perimeter Sealant Joints
Non-drainage EIFS
• Relies on 1/8” thick lamina and perfect sealant joints for waterproofing
• No secondary flashings to redirect incidental water to exterior
Non-drainage EIFS Problems
• Cracks, especially at re-entrant corners • EIFS finish coat wraps into sealant joint
(sealant should be bonded to base coat) • Open cell backer rod • No sealant joints at penetrations
Cement Plaster
• When installed properly, cement plaster works well
• All plaster cracks and absorbs moisture – there must be a complete WRB w/flashings to handle incidental water that penetrates the plaster
• Flashings at penetrations are critical
Cement plaster
• Window flashing is critical – see ASTM E 2112
Cement Plaster
• Tears and holes in the WRB caused by overdriven lath fasteners
• Water enters through lath fasteners not engaged with studs or other framing (i.e. “spinners”)
Thin Brick Veneer
• 3/8” to 3/4” thick bricks • Three basic installation systems:
– Embedded in precast concrete panels – Adhered to sheet metal or insulation
panels – Field-applied to exterior cement plaster
or concrete walls
Thin Brick Veneer Adhesion Failures
• Detection methods – Tapping – Prying
Thin Brick Veneer Panelized Wall Systems: Brick Adhered to Metal Panels
• Thin brick glued to aluminum panels
• Over rigid insulation • Nailed to plywood
sheathing • Bricks falling off
aluminum • Entire system
separating from building
Hardiplank
– Incomplete integration of Tyvek with window assemblies
– No flashing between Hardiplank and adjacent barrier EIFS or cornice ledger beam
Flooring Failures - Vinyl
• Newer low-VOC adhesives less tolerant of moisture in concrete slabs
• Shorter construction schedules lead to installing flooring before slabs are dry
• Lightweight concrete
Flooring Failures - Stone
• Use of thinner stones, low-quality stone, mortar bed shrinkage
Flooring Failures - Tile
• Shrinkage of underlying concrete slab
Balcony Deck Assemblies Observations – Cantilevered Balconies
How they fail and why you need saddle flashings
Membrane stops short of deck edge – no termination
Balcony Deck Assemblies
Building Wall (Plaster and WRB removed)
Wood Corbel
Balcony Deck (concrete and membrane removed)
Water runs off deck, remains behind plaster
Observations – Cantilevered Balconies
Balcony Deck Assemblies
Sealant joint between plaster and wood, but WRB unsealed
Water continues to run behind plaster, runs behind WRB edge
Observations – Cantilevered Balconies
Balcony Deck Assemblies
Unsealed WRB at bottom and side of wood corbel
Water bypasses WRB at edges
Observations – Cantilevered Balconies Water accesses and deteriorates OSB sheathing
Ageing of Early 20th Century Buildings
• Now being rehabilitated in urban areas
• Steel windows • Concrete or masonry
cladding
IV: Current Problems in the Building Process Why are there so many failures?
• New products being used without track record or testing
• Bidding with incomplete construction documents – usually schedule driven
• Low-bid contractors • Inadequate construction observation • Poor decisions during construction due to schedule
or budget
Thank you