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Professional Educational Series BSS75

Moisture Management and Residential Façade Design

CertainTeed is a Registered Provider with the AmericanInstitute of Architects Continuing Education System. Credit earned upon completion of this program will be reported to CES records for all AIA members. Certificates of Completion for non-AIA members areavailable upon request.

This program is registered with 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 product. Questions related to specific materials, methods, and services will be addressed at the conclusion of this presentation.

This course qualifies for HSW

This presentation is protected by U.S. and international copyright laws. Reproduction and distribution of this presentation without written permission of the sponsor is prohibited. CertainTeed Corp.

Copyright

After completing this course, you will be able to:– Describe the some of the primary functions of the building envelope.

– Describe the following as they relate to the principles of building envelope design:

• Science of Climates, Water Forms, Moisture Movement, Air Flow, Heat Flow, and moisture storage by material & system

– Describe the principle considerations pertaining to the design and construction of wall assemblies that address moisture flow and control

Describe the mechanisms by which materials wet and dry.

– Finally we will focus on the advantages and disadvantages of various kinds of residential wall claddings in the context of moisture control and durability

Learning Objectives

Functions of the Building Envelope

The boundary between interior and exterior

Must be:

• Structural (In most residential constructions)

• Must protect the interior from exterior elements- heat, cold, moisture, wind, and solar radiation

• Must be durable

• Must be efficient

• Must be sustainable

Functions of the Building Envelope

The Science of Moisture and the Building Envelope

The Science of Climates• The US has 8 climate zones

– 1 being the warmest and 8 being the coldest

• The US has 3 climate types– A = Moist

– B = Dry

– C = Marine

• Typical weather years influenced by

– Location of the Jet Stream

– Ocean Water Temperatures


The Science of Climate: Wetting

• Location– Total Rain Fall

– Wind Driven Rain

– Surrounding topography


The Science of Climate: Wetting

• Location– Total Rain Fall

– Wind Driven Rain

– Surrounding topography

• Geometry– Includes Height

– And Shape


Science of Climate: Drying• Drying according to

outdoor vapor pressures- vapor drive and environmental capacity


Science of Climate: Drying

• The influence of sunlight– On surface temperatures

– On air’s capacity to hold H2O

– On convective air flows


The Forms of Water


The Forms of Water

Dew Point: In simple terms, it is the temperature at which a given mass of water in the air will form condensation or “dew”. It’s like being at 100%RH and then dropping the temperature 1 degree


Specific Physical Mechanisms of Moisture Flow

• Water Flow – Gravity moves rainwater down

the building’s exterior surfaces• Water will enter downward-

sloped openings• Storm water runoff can flow

against buildings and seep in to basements

– Minimize water flow against the building

– Foundation drainage systems– Use shingles and flashings to

keep rainwater out of joints• Overlap the components • No reversed laps• Drainage holes• Protect vertical joints


• Capillary Suction– Caused by surface tension

of water• Causes water to be drawn

in through tiny pores in building materials

– To prevent capillary flow, create breaks in the components

– Even very narrow spaces work

• Should drain and vent to the exterior so drying can occur

• Moisture tolerant materials like concrete and masonry help prevent capillary flow


• Airborne Moisture Flow– Air flow carries moisture

into buildings– Construction practices

can prevent openings– The volume of moisture

entering a building by air flow can be 100 times greater than by diffusion

• Diffusion through a 4 x 8 sheet of painted gypsum board is about 1/3 quart of water over a heating season in a cold climate

• Air flow through a 1-inch hole can add up to 30 quarts!


• Water Vapor Diffusion

Air Flow Basics

• Air as an agent for wetting and drying

Heat Flow



• How stuff dries– 4 main parameters of evaporation rate

• Surface area• Surface temperature• Partial pressure of water in the air (%RH)• Air movement

Moisture Storage by Systems: How They Wet & How they Dry


Moisture Storage by Systems: How They Wet


Moisture Storage by Materials- maximum storage capacityMaximum Storage Safe Limit

• Masonry Mortar 8.03 lb./ sq.ft.• Brick 0.5 – 4 lb./ sq.ft.• Sandstone 0.6 – 2 lb. / sq.ft.• Fiber Cement 1.22 lb./sq.ft.• Stucco 1.12 lb./sq.ft.• Southern Yellow Pine 1.17 lb./sq.ft.• Spruce 3.3 lb./sq.ft.• Western Red Cedar 1.75 lb./sq.ft.• Vinyl Siding 0.0 lb./sq.ft.

• Plywood 1.43 lb./sq.ft.• OSB 1.22 lb./sq.ft.• Interior Gypsum Board 1.25 lb./sq.ft.• Fiber Glass Insulation 0.0 lb./sq.ft.• Cellulose Insulation 9.12 lb./sq.ft. (@ 3.5” depth)


unlimitedunlimitedunlimitedunlimitedunlimited17% - 21%17% - 21%17% - 21%unlimited

17% - 21%17% - 21%0.5% - 5%unlimited

17% - 21%

Moisture Storage by Systems: How they dry: Brick


Ventilation Rate 1-10 ACH

Moisture Storage by Systems: How they dry: Siding on vented space


Ventilation Rate100-1000 ACH

Moisture Storage by Systems: How they dry- Drained vs. Vented


Let us apply what we’ve learned.

A Focus on the Cladding

Lap Sidings

A Focus on Cladding

VS.

Brick Masonry

A Focus on Cladding

VS.

Stucco vs. EIFS

A Focus on Cladding

Stone vs. Stone Veneer

A Focus on Cladding

Stone Veneer vs. Stone Façade Siding

A Focus on Cladding

The Big Picture

We have…..Described the some of the principle functions of the building envelope.

– Described the following as they relate to the principles of building envelope design:

• Science of Climates, Water Forms, Moisture Movement, Air Flow, Heat Flow, and moisture storage by material & system

– Described the principle considerations pertaining to the design and construction of wall assemblies that address moisture flow and control

– Discussed each of the principle elements of framed wall assemblies as they pertain to moisture flow and drying

– Finally we focused on the advantages and disadvantages of various kinds of residential wall claddings in the context of moisture control and durability

Summary

Credit Information

• Your certificate of completion will be available at the CertainTeed Academy of Continuing Education continuinged.certainteed.com

• You will receive an email with a link to access your certificate

• If applicable, update your profile with your AIA number for reporting. Reporting is uploaded to AIA once a week.

Thank You for YourParticipation

AnyQuestions?

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