WELCOME VENTED and UNVENTED Roof/Deck Systems AGENDA WHY - - PowerPoint PPT Presentation

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WELCOME VENTED and UNVENTED Roof/Deck Systems AGENDA WHY - - PowerPoint PPT Presentation

Apr 20, 2023 28 likes •523 views

WELCOME VENTED and UNVENTED Roof/Deck Systems AGENDA WHY IMPORTANT CODE THEORY EXAMPLES QUALITY CONTROL awareness responsibility standards WHY IMPORTANT IMPORTANT More attic rain Complex

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VENTED and UNVENTED Roof/Deck Systems

WELCOME

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awareness responsibility standards

AGENDA

  • WHY IMPORTANT
  • CODE
  • THEORY
  • EXAMPLES
  • QUALITY CONTROL
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SLIDE 3

WHY IMPORTANT

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awareness responsibility standards

IMPORTANT

  • More “attic rain”
  • Complex

buildings

  • Longer warranty

periods

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awareness responsibility standards

IMPORTANT

  • Design

considerations

  • Think about
  • ptions early in

process

  • Design,

construction, cost, sequencing

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awareness responsibility standards

IMPORTANT

  • Vented isn’t
  • nly option
  • Doesn’t always

work

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IMPORTANT

  • “The Ventilation of Insulated Roofs” -

Ottawa 1985 NRCAN

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awareness responsibility standards

IMPORTANT

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awareness responsibility standards

IMPORTANT

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CODE

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awareness responsibility standards

CODE

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awareness responsibility standards

CODE

  • Insulation on top – no venting required
  • Insulation below
  • Vent as per 9.19 or
  • Prove it is not required
  • Fire code – solid soffits
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awareness responsibility standards

CODE

2014 ABC – 1 page on VENTING requirements Standard WITHDRAWN

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CODE

  • “In particular, the rule requiring an attic ventilation ratio of 1:300

does not appear to have been justified at the time of its

  • promulgation. The research that was intended to substantiate the

rule fails to support it. The promulgation of the 1:300 rule went forward.” The History of Attic Ventilation Regulation and Research, William B. Rose

  • “However, we believe it should not be a regulated practice.”

ASHRAE Journal

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awareness responsibility standards

CODE

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awareness responsibility standards

CODE

  • Commercial
  • All insulation on top
  • Simpliest
  • Often most expensive
  • Difficult tie-ins
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awareness responsibility standards

CODE

  • Vented
  • Best for simple designs
  • Still may need guidance on

amounts, type and location of vents

  • Still need to regulate interior

humidity and ensure proper air/vapour barrier

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CODE

  • Unvented
  • Technically allowed, but many AHJ

require professional review

  • Allowed in IRC
  • Hopefully allowed in 2020 NBC
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THEORY

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awareness responsibility standards

THEORY

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awareness responsibility standards

THEORY

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THEORY

  • 1940s buildings did not have vapour

barriers

  • To prevent condensation
  • Humidity control
  • Air/vapour control
  • Ventilation
  • Helps drying if assembly gets wet
  • Some belief it will help shingle life
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awareness responsibility standards

THEORY

  • Complications now-vented
  • Building complex, mixing roof types
  • More flat roof (increased density)
  • Wind driven rain (increased heights)
  • Roof assemblies vary
  • Fire Code
  • Buildings tighter
  • Previous assumptions don’t apply
  • No good design guidelines
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awareness responsibility standards

THEORY

  • Unvented basics
  • Done for years (cathedral, vaulted, flat)
  • Reduce chance of condensation
  • Depending on project, several ways
  • Spray foam, hybrid (foam/batt), cellulose/osb

(passive)

*Building science.com

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EXAMPLES

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EXAMPLES

  • Flat Roof-Commercial
  • Pros
  • easy installation
  • slope
  • Cons
  • Expensive
  • Can get high
  • Wall vapour barrier

tie-in

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awareness responsibility standards

EXAMPLES

  • Builders and

designers don’t consider ventilation at beginning

  • Just add more

vents

  • Add a power vent
  • Ventilation often an

afterthought

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awareness responsibility standards

EXAMPLES

  • Vented with baffles
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awareness responsibility standards

EXAMPLES

  • When to consider unvented
  • Decks over living
  • Don’t have 63mm min free airflow
  • Blocked ventilation paths
  • Complex roofs
  • Flat roofs
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EXAMPLES

  • Can do

unvented for standard roofs

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EXAMPLES

  • Completed over 230 unvented roof

projects since November 2014

  • Each project unique requires
  • Assembly
  • Specifications
  • Initial stamp
  • City of Calgary – site review
  • Roof/deck installation not part of

unvented design

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awareness responsibility standards

EXAMPLES

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awareness responsibility standards

EXAMPLES

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awareness responsibility standards

EXAMPLES

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awareness responsibility standards

EXAMPLES

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awareness responsibility standards

EXAMPLES

  • Unvented Decks
  • Need drainage
  • Where to?
  • Concrete expensive to

remove

  • What is it covering?
  • Roof detailing
  • Flat roof with activity on

top = HIGH RISK

  • Protected vs unprotected

membrane

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QUALITY CONTROL

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awareness responsibility standards

QUALITY CONTROL

  • DESIGN
  • Commercial, vented, unvented, combo
  • Review drawings early on for venting issues
  • Closed soffits
  • Skylights
  • Structure – beams, low trusses
  • Flat roofs
  • Penetrations
  • Vent locations
  • Realize unvented is an option
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awareness responsibility standards

QUALITY CONTROL

  • High risk factors
  • Deck over living
  • Internal drains
  • Penetrations
  • Solar panels
  • Maintenance-access
  • Concrete toppings
  • Interior lights/penetrations
  • Plumbing lines
  • Bathrooms – humidity sources
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awareness responsibility standards

  • During construction
  • Any changes in design
  • Pre-review
  • Photos
  • Material changes
  • Inspector/other trade changes
  • Ok to question
  • Request Code Section clarification

QUALITY CONTROL

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awareness responsibility standards

  • Actual install of spray foam
  • Framing issues – block installation
  • Use of low density
  • Steel
  • Extra insulation required?
  • Tie ins
  • Air barrier continuity
  • Actual spray foam

QUALITY CONTROL

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awareness responsibility standards

  • Actual install of spray foam
  • Framing issues – block installation
  • Use of low density
  • Steel
  • Extra insulation required?
  • Tie ins
  • Air barrier continuity
  • Actual spray foam

QUALITY CONTROL

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awareness responsibility standards

QUALITY CONTROL

  • Spray foam
  • CAN/ULC S705.2
  • CCMC Listing
  • Form – product/thickness
  • Applicator check
  • Temperatures
  • Density
  • Prepare logs
  • Correct long term thermal

resistance (LLTR)

  • Check quotes carefully
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awareness responsibility standards

QUALITY CONTROL

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awareness responsibility standards

QUALITY CONTROL

  • If vented and using poly,

need to ensure done well

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awareness responsibility standards

  • OCCUPANCY
  • Flat roofs
  • Let owners know need to maintain
  • Vented – owners shouldn’t be putting

holes in v.b.

  • Leakage
  • Investigate properly
  • Leakage may take longer with

unvented

QUALITY CONTROL

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awareness responsibility standards

  • Various venting and unvented design

strategies

  • Depends on design, location, and

budget

  • More complex designs require careful

review

QUALITY CONTROL

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awareness responsibility standards

QUESTIONS

  • Questions
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awareness responsibility standards

THANK YOU

If you have any further questions please contact us. Dana Bjornson 403.990.3369 dana@optimizeengineering.com