Successful Through Wall Flashing Systems

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SuccessfulThrough Wall Flashing Systems

• Prepared by
• Lennel Specialties Corporation
• www.lennelspecco.com
• Edited by
• Richard Keleher

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The Problem

• The age old problem that the construction
  industry has been faced with is moisture
  infiltration in its liquid form into building
  exterior walls and interiors due to through wall
  flashing failures.

This problem can lead to
Damage to interior finishes
Tenant discomfort and complaints
Indoor air quality problems due to
mold and fungus growth
Damage to the structural elements of the
building
Efflorescence
Loss of clients
Litigation
Owners are no longer putting up with leaky
buildings. 80 of construction litigation is due
to moisture infiltration problems.
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Corroded light gage metal framing back up systems.
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Corroded relieving angles.
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Mold growth in exterior wall insulation.
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Efflorescence
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The Solution

• Consider carefully

Design
Detailing
Materials
Workmanship
Coordination
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Design

• Dont design a building that cannot be
  effectively or efficiently waterproofed

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Ten Cambridge Center Cambridge, MA
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Detailing

• Details should be clear and complete.

Use three dimensional details for corners,
panning and other intricate details.
Think about where the moisture is going to flow
when drawing details.
Make sure your details get the moisture out past
the face of the wall.
CAD makes detailing so much easier. A library of
details can be developed to detail most
conditions on most jobs.
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Is this a through wall flashing ?
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Materials
Copper Core Composites Copper with asphalt
saturated kraft paper Asphalt coated
copper Copper fabric flashing Benefits /
Problems Will last a long time Hard to work with
in the field How long will the lap sealant
last? Not compatible with sealants
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Copper composite flashings are difficult to lap
effectively.
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Copper fabric flashing at sill application
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Materials
PVC Excellent material to work with,
but.. Plasticizer migration will cause it to
become brittle and crack over time Not UV
resistant Not resistant to some solvents Not
very durable AIA/ Masterspec dropped it from
their specifications in 1999
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Torn PVC flashing
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Materials
EPDM / - 60 mil membrane hard to bend, fold
lap Adhesive application causes some
problems Note EPDM is now available in 40 mil
thickness and can be sealed, lapped and embedded
in mastics and mastic type products.
Self Adhering Flashing Self sealing at splices,
punctures and penetrations Cannot withstand
prolonged exposure to UV rays Not compatible
with sealants Keep material back 1/2 from the
face of the wall Do not bridge gaps greater
than 1/4 wide
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Self adhering flashing oozing its rubberized
asphalt
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Materials
16 oz. Lead Coated Copper Will last a long
time Excellent for forming end dams and
corners Not adaptive to job site conditions Very
expensive to purchase and install ( / -
10.00 / sf / - 2.00 / sf of brick veneer
) Can leach a white residue Lap and joint
treatment must be considered
Stainless Steel Will last a long time Hard to
solder for end dams and corners Not adaptive to
job site conditions Very expensive to purchase
and install ( / - 15.00 / sf / - 2.50
/ sf of brick veneer ) Can reflect sunlight
depending on finish
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External Corner
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Internal Corner
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Why is my building leaking???
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Workmanship

• 90 of flashing problems are due to poor
  workmanship

To help avoid these problems
Use clear, concise and complete details
Choose user friendly materials
Have a pre-construction envelope meeting with
The general contractor
The cladding (masonry) contractor
The metal stud contractor
The window contractor
The sealant contractor
The air barrier flashing installers
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Mortar Net weep baffle.
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Stepped through wall flashing.
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Wall flashed to weep inside the building.
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Typical Use Mortar Net!
Typical Provide Insulation (Angle should be on
Brackets)
Typical Use Backer Rod to Allow for Deflection
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Typical no insulation!
Now this works!!!!!
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Typical LCC or SST for Whole Flashing
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Why is my building leaking?
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Typical Use Metal Flashing with End Dams
Typical Air Vapor Barrier (dotted)
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Masonry opening jamb.
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?
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Self adhering jamb flashing that did not stay
adhered.
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Typical Add Jamb Flashing
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Damn!!!! No end dam. We have a leak.