This registration page may not work well in Internet Explorer. Please use a different browser to complete your registration.

Avoiding Double Vapour Barriers: A Fundamental Principle Overshadowed in Some Current Design Practices

September 3, 2026 7:30 AM - 12:00 PM (PDT)

Description

CPD - 4 credits 

Course Overview:

Avoiding double vapour barriers in building assemblies is among the foundational principles of building science. This guidance was reinforced for decades through the education and research conducted by the Division of Building Research at the National Research Council of Canada throughout the 1960s, 70s, and 80s, and captured in publications such as the Canadian Building Digests and reference texts like Building Science for a Cold Climate. This fundamental has long been embedded in Canadian Building Code provisions and remains central to durable, predictable building‑envelope performance.

While this topic received significant attention historically, recent years have seen the introduction of various assemblies—often configured to meet energy‑efficiency targets—that create double‑vapour‑barrier conditions. In many cases, these configurations have led to performance failures, compromised long‑term durability, and nuisance conditions for end users. Forensic reviews confirm that these outcomes are not attributed solely to construction error; rather, in many cases, the underlying issues stem from design decisions.

This session revisits the principle of avoiding double vapour barriers by examining its historical context, highlighting why this “old wisdom” remains crucial for long‑term durability, and reviewing how it should continue to inform design decisions. Using case studies supported by photos, videos, field documentation, and mobile roof and wall assemblies, the session will illustrate where design choices have disregarded this principle and will provide practical, reliable takeaways to support performance, durability, and end‑user experience.


Agenda:

7:30 AM - 8:00 AM: Breakfast and Networking

8:00 AM - 12:00 PM: Course


Speaker:


Hamid Heidarali is a Building Science specialist at HDB with a strong passion for high performance buildings that minimize their impact on the environment, while providing superior experience for occupants. He has been providing Building Science engineering on a wide range of projects in Canada over the past two decades. Hamid taught building envelope courses to Masters students at British Columbia Institute of Technology (BCIT) from 2015 till 2020, and offers holistic building envelope workshops for the construction professionals on a regular basis.

Time

7:30 AM - 12:00 PM Pre-registration is required.


View Event

Contact Information

Homebuilders Association Vancouver (HAVAN)
Name: Sonali Rayas
Phone: (778) 867-8415
Email: sonali@havan.ca
We're sorry. No registrations are currently available. You may wish to contact the event organizer for assistance.
{{ vm.EventInfo.ErrorMessage }}

Select Registration Options

Edit
{{vm.regWarningMessage}}
{{vm.regAlertMessage}}

Exhibitor Opportunities

Name Price Att Qty
{{ et.Name }}
{{ et.IncludedAttendeesCount }} {{ et.AttendeeRegType.RemainingPerType }} Remaining {{ et.AttendeeRegType.RemainingPerType * -1 }} on Waiting List {{ et.AttendeeRegType.RemainingPerType * -1 }} Over Limit
{{ et.Remaining }} Remaining
 Sold out

Attendee Registration Options Total Remaining: {{ vm.EventInfo.VacantSpotsPerEvent }}

Waiting List Available
{{ vm.stats.totalAttendeesCount }} Registered , {{ vm.OverallOverAmount() }} on Waiting List , {{ vm.OverallOverAmount() }} Over Limit
Name Price Qty
{{ rt.Name }}
{{ rt.IsMemberOnly ? ' (Members Only)' : '' }}
Limit: {{ rt.LimitPerPurchase }}
Included Attendees: {{ rt.AttendeesCountPerOneRegistration }}
{{rt.Price | currency }} {{rt.PriceAfterDiscount | currency }} {{ rt.Price | currency }}
{{ rt.RemainingPerType }} Remaining
{{ rt.RemainingPerType * -1 }} on Waiting List
{{ rt.RemainingPerType * -1 }} Over Limit

{{'[[Sponsorship]] Opportunities' | localizeString:'['}}

Name Price Att Qty
{{ st.Name }}
{{ st.IncludedAttendeesCount }} {{ st.AttendeeRegType.RemainingPerType }} Remaining {{ st.AttendeeRegType.RemainingPerType * -1 }} on Waiting List {{ st.AttendeeRegType.RemainingPerType * -1 }} Over Limit
{{ st.Remaining }} Remaining
 Sold out
Continue

Registration Information

Edit

Exhibitor - {{er.Name}}

Exhibitor #{{ $index + 1 }}

Total: {{exhibitor.TotalPrice | currency}} {{ exhibitor.IsBenefit ? "- Included as a Benefit" : exhibitor.IsDiscounted ? "- Discounts have been applied" : ""}}
Exhibitor Directory
Primary Contact
Booth Information
Additional Information
Additional Items

Attendee - {{er.Name}}

{{ att.getAttendeeTerm(vm.EventSettings.AdditionalAttendeesTerm, $index) }} #{{ att.getAttendeeIndexDisplay(vm.EventSettings.AdditionalAttendeesTerm, $index) }}

Total: {{att.TotalPrice | currency}} {{att.DiscountMessage | localizeString:'['}}
A No Show fee is being assessed for {{fee.EventName}} on {{fee.EventStartLocalTimeString}}.
More Information Less information

Address

Phone

Additional Information
Event Sessions

{{slot.Name}}

{{$select.selected.SessionName}}
(full)
{{slot.SelectedSession.SessionDescription + (slot.HasFees ? " (Price: " + (slot.PriceTotal | currency) +")" : "")}}
Additional Items

{{'[[Sponsorship+]]' | localizeString:'['}} - {{er.Name}}

{{'[[Sponsor]]' | localizeString:'['}} #{{ $index + 1 }}

Total: {{sponsor.Price | currency}}
Continue

Additional Items

Edit

{{(vm.EventInfo.Terms.Donation || "Fundraising") + " Opportunities"}}

Campaign Name Item Description Amount
{{item.CampaignName}} {{item.Description + (item.ShowMinimumPrice && item.MinimumPrice ? " (Min: " + item.MinimumPrice + ")" : "")}}
Continue

Complete Registration

Edit

Terms & Conditions

No Show Policy

{{ vm.EventInfo.EventSettings.NoShowPolicy }}

Enter Promo Code

Billing Contact

Registration Protection
This event is synced to a webinar so no confirmation email will be sent from GrowthZone.

Thank you to our {{'[[Sponsor+]]' | localizeString:'['}}