building envelope transitions: key to success or failure

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Smart Engineering

of Roofs, Walls,

Pavements and

Waterproofing

Building Envelope Transitions: Key to Success or Failure

Michael D. Remington, P.E.

November 8, 2016

INSPEC

Inspec is an award-winning independent engineering/ architectural consulting firm founded in 1973, and is dedicated to improved design, construction practices, and maintenance of the building envelope.

• Roofs• Walls• Windows• Waterproofing• Civil Engineering: Pavements, Outdoor Sports

Facilities, Stormwater Management

Key Building Envelope Transitions:

• Roof-to-Wall

• Wall-to-Wall/Wall-to-Window

• Wall-to-Foundation/Plaza

What’s Different At Transitions?

What Isn’t!

• Materials

• Angles/Corners

• Flashings

• Movement

• Detailing

Importance of a Tight Building Envelope

• Keeps out water, vapor, and wind.

• Saves energy related to heating and cooling.

• Prevents condensation from occurring inside building components and related damage.

• Prevents mold and indoor air quality problems.

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Condensation Within Building Assemblies

The trend towards tighter enclosures, reduced airchange, and higher levels of interior moisture can lead to:

• Condensation within insulated assemblies

• Elevated incidences of interior surface mold and mildew

Keeps Out Water, Vapor, and Wind

• Uncontrolled Rain and Moisture Entry Represent Up to 80% of All Construction-Related Claims in the U.S.

Controlling Moisture Movement

The objective is to:• Prevent building envelope problems

before they occur• Save building owner unnecessary

maintenance and energy costs

Saves Energy Related to Heating and Cooling

• Studies Have Found as Much as 40% of HVAC Costs in a Building are Related to Air Leakage.

Infrared Thermography

Location of Heat Loss

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Prevents Condensation From Occurring Inside Building Components and Related Damage

So How Do We Achieve a Tight Building Envelope?

• Continuity of Transitions

• Teamwork

• Mock-ups

• Compatibility of Materials

• Quality Control and Testing


• Transitions/Teamwork


• Continuity of Transitions- Requires Proper and Thorough Design

and Detailing of Building Interfaces and Transitions

- ‘Generic’ Design vs. ‘Thorough’ Design

- Who’s Responsible for Major Design Decisions: the Architect/Engineer or Contractor?

- Dangers of ‘Value’ Engineering


• Teamwork

- Peer Review/Commissioning- Pre-Installation Meetings with the

Different Trades

- Confirm Product Compatibility- Develop a Common Understanding

and Effective Communication of Project Goals


• Mock-ups

- Identify and Solve Problems Beforethe Project is Substantially Complete

- Good ‘Practice’ for Coordinating the Various Trades

- The ‘Proof is in the Pudding’

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• Compatibility of Materials

- Certain materials when used together are incompatible and cause degradation.

- For Example: Asphaltic products can swell and distort membrane; solvents in some products can attack other products.

Incompatibility of Materials



• Quality Control and Testing

- Mock-ups

- ‘Early’ Testing

- Whole Building Testing

- Infrared Imaging

- Construction Observation

Mock-ups ‘Early’ Testing

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Why Use Air Barriers and Vapor Barriers?

• Increased Energy Efficiency

• Extended Building Life

• Improve Indoor Air Quality

Moisture’s 3 Physical States

• Solid

• Liquid

• Gas

Water: Liquid vs. Vapor

• Vapor is a single molecule

• Liquid is molecular clumps, 60 or more

Images from buildingscience.com

Methods of Moisture Movement

• Liquid Flow

• Capillary Action

• Vapor Diffusion

• Air Movement

Rules of Moisture Movement

• Flows Downhill

• Moves From Higher Humidity to a Lower Humidity

• Moves From Higher Vapor Pressure to Lower Vapor Pressure

• Moves From Warmer Temperatures to a Cooler Temperature

Dew Point

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Dew Point

• Knowing the dew point location is important when designing the building envelope.

• In some climates, the dew point may be reached within the wall during winter months.

Vapor Diffusion

The movement of moisture vapor is not a serious problem until the dew point temperature is reached and the vapor changes into liquid moisture (condensation).

Diffusion vs. Air Leakage

Source: Building Science Corporation ‘Builder’s Guide’

Movement of Moist Air(Mass Transport)

Mass Transport of water through air movement is potentially the second most important mechanism for moisture intrusion into building walls and roofs.

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Which is More ‘Dangerous’: Diffusion or Mass Transport?

• Rainwater and air leaks generally occur at specific locations such as cracks or joints (transitions), and do not affect the entire wall or roof surface.

• Diffusion is a slow process and changes direction infrequently. Moisture can move into wall cavities over a period of time without reversal, slowly saturating materials and causing deterioration.

Which is More ‘Dangerous’: Diffusion or Mass Transport?

• Therefore, vapor diffusion can result in substantial amounts of moisture accumulation within the building envelope over long periods.

• Results in significant potential to cause serious deterioration.

Application

Moisture control must be addressed with all structures, and special attention given to facilities with high interior humidity:

• Indoor swimming pools or hot tubs

• Commercial kitchens or laundries

• Gymnasiums

• All air-conditioned buildings in warm and humid climates

What Might You See?

• Efflorescence

• Spalled Masonry

• Rust Jacking

• Cracks or Spalls at Rebar Locations

• Mold

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Leaks

Location TypeRoofs Water

Walls Air

Windows Heat/Energy

Mystery

Preventing and Responding to Building Leaks

• Roof/Wall/Window Condition Assessments

• 5 or 10 Year Management Plans

• Proactive vs. Reactive Approach

Finding and Solving Leaks

Historical Information•Locations

•Weather

•Dates


• Leak Testing


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• Infrared Scans

Roof Leaks

The Moisture’s Not Always This Obvious!


Image courtesy of Fluke Cameras

Finding Leaks in Buildings


Advantages of Infrared Building Diagnosis• Fast, noninvasive, safe – minimizes need for building

disassembly

• Find moisture sources and other problems quickly

• Locate heating & cooling losses

• Minimize disturbance of occupants and ongoing operations

• “Real time” results

• Document as-built or post-repair/restoration conditions

Finding Leaks in RoofsThermography

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Finding Leaks in RoofsThermography Suspected Wet Insulation

Suspected Wet Insulation Thermography and Roofs

What Are The Facts?

• Wet Insulation

• How much is wet?

• Where is it wet?

What Are The Facts?

• Wet Insulation = Energy Loss = $

• Dry Insulation = Re-use = $

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Finding Energy Leaks in BuildingsEnergy Audits Finding and Solving Leaks

• Test Openings

Case Study: Minneapolis Institute of Art

Leak Investigation at Mill and Main East

Water Test at parapet above lobby Spray Rack above parapet

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Leak Investigation atMill and Main East

Area of water penetration Cap Flashing Removed


Roofing membrane cut shortRusted fasteners from brick support metal (white surface)


Drainage plane and air barrier provide access for moisture into the structure

Edge flashings cut off leaving sheathing exposed

Leak Investigation atMill and Main East

Membrane flashings installed below the drainage planes and to protect parapet blocking

Questions?

building envelope transitions: key to success or failure

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