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CSA S478 Guideline on

Durability in Buildings

David Kayll, FMA, P.Eng.Principal, Building Science Specialist

MORRISON HERSHFIELD, Ottawa

May 8, 2014

The Durability Process

Take a deep breath'

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1What Determines Durability?

� Durability is not a material property

� Durability is a function of a material

and its environment

� Durability is also a function of

installation, future maintenance

and replacements

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Durability

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1Service Environment

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Durability

Location &

Exposure

Interior

Loads

1Required function(s) of:

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Durability

That depends on whether we are

manufacturing open web joists or

underwear.” Ted Kesik

Buildings:

Institutional, Industrial, Commercial, Residential'

Materials:

“What’s better – steel or cotton?

Durable requires the Team to perform their roles and

responsibilities from Conception to Occupancy.

Roles & Responsibilities

The Roles need to be clearly

defined for each of the following:

� Owner(s)

� Architect

� Durability Specialist

� Building Envelop Consultant

� Structural Consultant

� Other Consultants

� General Contractor

� Sub-Contractors

� Manufacturers

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A Durability Plan

Creating a Durability Plan

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The CSA S478 guideline provides:

� Set of recommendations to assist designers

� Framework for durability targets

� Generic advice

� Model documents

� Appendix with expanded discussions

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A Durability Plan

Tables, Design review, Field review

Sample MH Durability Plan

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A Durability Plan

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Service Life

Service Life:

� “The actual time during which the

building or any of its components

performs without unforeseen costs

or disruption for maintenance and

repair.” (CSA S478)

� Design Service Life (DSL) vs.

Predicted Service Life (PSL)

� Components will last for 10, 20, 30,

50, 100+ years?

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Predicted Service Life

Historical Materials – We know these ones'

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Predicted Service Life

Innovative Materials – Do we know these ones'???

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Agents of Destruction

Agent Type

Moisture Solid (ice, snow)

Liquid (rain, condensation)

Gas (water vapour, humidity)

Air Constituents O2, CO2

Air Contaminants Oxides, particulates, sea spray

Ground constituents Sulphates and other salts, acids (from

decomposition of organic matter)

Ground contaminants Chemicals from spills and leaks,

chlorides from road salt, induced

electrical currents

Biological agents Microorganisms, insects, other

animals, plants

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Agents of Destruction

Agent Type

Temperature Fluctuations

Solar radiation UV (ultraviolet radiation)

Incompatible

chemicals

Corrosion

Differential

movements

Between components (shrinkage

and swelling), within massive

materials (temperature gradient

response), creep/flow

Use or

exposure

Loading, abrasion, overloading

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How To Predict Service Life?

How do we predict the service life of a material or assembly?

� PSL of components within assembly

(shortest outside, longest inside)

� Use many methods in parallel

� Some components will be less

� Some components will be more

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How To Predict Service Life?

ISO 15686-1 Factor Method:

ESL = RSL x A x B x C x D x E x F x G

A. Quality of components as supplied to the project

B. Design level of a component (e.g. how protected it is from elements which may

degrade it)

C. Work execution level or skill level of the installers

D. Indoor environment (e.g. where the component will be utilized)

E. Outdoor environment (e.g. northern climate, coastal climate, southern climate)

F. In-use conditions (refers to specific use conditions of the building)

G. Maintenance level (what is the level of maintenance possible, and likely, for the

particular component for the span of its useful life?)

??

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CSA S478 Method

� Engineering judgment

� Historical performance

� Chemical evaluation

� Modeling

� Performance testing

� Manufacturer’s estimates

Plus:

− Environmental conditions

− Installation

− Operating & Maintenance procedures

How To Predict Service Life?

1Owner’s expectation of Design Service Life

� Ownership type

� Building use (present and future)

� Future land development

� Adaptability

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A Durability Plan

How do you determine a building’s Design

Service Life?

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A Durability Plan

Category DSL Examples

Temporary Up to 10 years * Non-permanent construction buildings (sales offices, bunkhouses)

* Temporary exhibition buildings

Medium Life 25 to 49 years * Most industrial buildings

* Most parking structures

Long Life 50 to 99 years * Most residential, commercial and office buildings

* Health and education buildings

* Parking structures below buildings designed for long life category

Permanent 100 years

minimum

* Monumental buildings

* Heritage buildings

Design and construct with the intent that:

Predicted Service Life ≥ Design Service Life

Table 2 in CSA S478

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A Durability Plan

Category DSL Examples

Temporary Up to 10 years * Non-permanent construction buildings (sales offices, bunkhouses)

* Temporary exhibition buildings

Medium Life 25 to 49 years * Most industrial buildings

* Most parking structures

Long Life 50 to 99 years * Most residential, commercial and office buildings

* Health and education buildings

* Parking structures below buildings designed for long life category

Permanent 100 years

minimum

* Monumental buildings

* Heritage buildings

Design and construct with the intent that:

Predicted Service Life ≥ Design Service Life

Table 2 in CSA S478

1Component DSL in accordance with Table 3 in CSA S478:

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Service Life

Category Effects of failure Example

1 No exceptional problems Replacement of light fittings

2 Security compromised Broken door latch

3 Interruption of building use Repair requires discontinuation of service

4 Costly because repeated Window hardware replacement

5 Costly repair Extensive replacement/ scaffolding needed

6 Danger to health or ecological system Mold, dampness, asbestos

7 Risk of injury Loose handrail

8 Danger to life Collapse of structure

� Components in Categories 6, 7 and 8

– Design to last the life of the building

� Components in Categories 4 and 5

– Design to last at least half the life of the building

1Where:

Component(s)/Assembly DSL < Building DSL

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A Durability Plan

What is “!readily replaced!”?

- Design and construct those component(s) and

assemblies so that they can be readily replaced.

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A Durability Plan

DSL1

DSL3

DSL5

DSL4

DSL2

DSL6

General Rule: Shorter PSL outboard of longer PSL

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A Durability Plan

Concept Design Review

� Review against the Owners

Project Requirements

� By someone not directly involved

in the main design functions.

� Could be separate specialist

� Document that Concept Design

Review was completed

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A Durability Plan

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A Durability Plan

Design Review

� Sufficient Building Envelope reviews are

required to demonstrate compliance with

good practice.

� Reviews include managing: − Air leakage

− Vapour diffusion

− Heat transfer

− Water penetration

� Method may include:− Marked-up drawings

− Letter report(s)

− Meeting minutes

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A Durability Plan

Maintenance Requirements

Maintenance Requirements & expectations

developed during design:

� Appropriate material selection

(component by component)

� Frequency & Access of

Maintenance/Repair

(future costs); Initial Cost vs. LCC

� Risks associated with poor

maintenance – Condos vs. Owner occupied

� Document Owner acceptance of

unusual decisions

Vs.

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A Durability Plan

Maintenance Requirements

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A Durability Plan

Commissioning the Building Envelope

BECx activities should be incorporated into

specifications. These may include:

� Testing requirements

(manufacturer or on-site)

� Shop drawing submittals

� Material submittals

� Material Compatibility Testing

� Mock-ups

� Manufacturer’s field reviews

� Sample removals/renewals

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A Durability Plan

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A Durability Plan

Quality Assurance makes sure you are

doing the right things, the right way.

Quality Control makes sure the results of

what you've done are what you expected.

Quality Management

Whose job is Quality?

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A Durability Plan

Key for all projects:

� Sub-contractor’s workmanship & quality control

� Potential transition issues

� The contractor’s Quality Assurance activities

� The Architect’s or BEP’s Quality Review

activities

� The expected quality of installation

(assists in finalizing the PSLs)

� The roles and responsibilities of all team

members

Mock-ups

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A Durability Plan

� To assess installation quality

control,

� Address “one-off” details

� Quality assurance activities are

documented.

� A final review is required to

confirm compliance with the

Project Documents.

� Frequency is dependent on

team make-up and

requirements

Periodic Site Review

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A Durability Plan

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A Durability Plan

� The Durability Plan must be endorsed by the

Owner (critical step)

� The Contractor must state that the building

was constructed in general conformance with

the Project documents.

Final Sign-off

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A Durability Plan

Appendices and Tables

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QUESTIONS?QUESTIONS?QUESTIONS?QUESTIONS?