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Better Design & Building Practices for Reducing

Moisture Problems in Commercial Buildings

Steve Easley, Steve Easley & Associates Inc. 925-698-

4726 Email- steve@steveeasley.com

Learning Objectives

Understand how moisture impacts

building performance

Identify common design defects that lead

to moisture problems

Identify common construction defects

that lead to mold and decay

Understand mechanics of moisture

movement

Learn how to properly flash penetrations

Wood Products Council is a Registered Provider with The

American Institute of Architects Continuing Education

Systems. Credit earned on completion of this program will be

reported to CES Records for AIA members. Certificates of

Completion for non-AIA members are available on request.

This program is registered with the AIA/CES for continuing

professional education. As such, it does not include content

that may be deemed or construed to be an approval or

endorsement by the AIA of any material of construction or any

method or manner of handling, using, distributing, or dealing

in any material or product. Questions related to specific

materials, methods, and services will be addressed at the

conclusion of this presentation.

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Copyright Materials

This presentation is protected by US and

International Copyright laws. Reproduction,

distribution, display and use of the presentation

without written permission of the speaker is

prohibited.

© Steve Easley & Associates/Wood Products Council

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Our Expectations for

Building Enclosures

They keep building components dry

They maintain a temperate

environment

They are long lasting

They do not make you sick

Goals for Building

Building Durability

Energy Efficiency

Comfort

Healthy and Safe

How Wall Assemblies

Get Wet

Bulk water intrusion

Air current induced moisture

vapor movement

Vapor migration by diffusion

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Bulk Water Infiltration Mechanisms

Gravity PressureDifferential

Capillary Action

Rain is the Main Source of Water for Above

Grade Envelope

Rain Driven

Moisture Damage

Stain and mold on

Batt Insulation

Corroded Fasteners

Rust top track at slab

edge

Durability

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Managing Water &

Moisture

Job 1 keep out the water

Job 2 Eliminate air in/exfiltration

Job 3 Design so the building can dry

Water moves as a liquid and a vapor

Leaks in the building enclosure

Moisture vapor piggy-backs on air movement

Buildings components get

wet by:

Water Leaks and moisture laden air

infiltration or exfiltration

They dry by evaporation or

diffusion

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Remember

It only takes minutes for building

components to get wet…

But it takes days or weeks to dry

out.

Building materials dry only by

evaporation or diffusion.

Misconception #1

One of the biggest misconceptions in the building industry today is:

Building a leaky building enclosure and air infiltration leads to better drying of building components

Air is most always warmer

and wetter than the air it is

driven to. Why??

Heat moves from warm to cold

Moisture moves from wetter to dryer areas

Buildings dry more to the inside during summer

Building dry more to the outside in cold climates during winter

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MechanicalPressure(HVAC)

StackPressure

Sources of Air Pressure

Differential

in Buildings

WindPressure

Misconception #2

One of the biggest misconceptions in the building industry today is:

Moisture transport by diffusion is a significant mechanism for the wetting of building components.

Basic thoughts about

walls…

Colder temps usually contribute to wetter

areas and higher surface relative

humidity

Warmer temps usually contribute to dryer

surfaces and lower surface relative

humidity

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Approaches to Moisture

Management

the 4 D’s

Deflection

Drainage

Drying

Durable Components

Design

Recommendations

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Steve Easley

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Kickout Diverter by Dryflekt

Kickout diverter by Dryflekt

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OSB VS. Plywood

Plywood and OSB at a

Glance

Plywood Average swell= 6% to 8%

(depending on thickness)

OSB Average swell= 10% to 15%

(depending on thickness)

Sag or Creep @85% R/H

Plywood 85% R/H 1.9mm

OSB 5.2mm

Plywood is 10% stiffer than OSB

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Plywood and OSB at a

Glance

Withdrawal strength (lbs/in. penetration)

Plain Ring

Screw5/8 Plywood Mean: 79.7 316.3 83.7

23/32 OSB Mean: 67.6 281.5 63.9

Higher Impact resistance

15-19% lighter than OSB

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Flashing

Systems

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Steve Easley

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All Water Should

Run To Daylight !