Issue # 18: Air, Weather & Vapour Barriers
ISSN 1703-5597
October 1, 2003

Issue #18 Air, Weather & Vapour Barriers

  1. The Basics: Glossary, Heat Air & Moisture, Air Leakage
  2. Air Barriers: Requirements, Permeance, Association
  3. Air Barrier Products: ADA, Foam, Caulks & Sealants
  4. Weather Barriers: Choosing, Installing, Test Results
  5. Vapour Barriers: Yes? No? Maybe? The Debate Goes On
  6. Vapour Barrier Products: Standards, Types, Smart
  7. Other Resources: Seminar, Database, Barriers For Reno

1. The Basics: Glossary, Heat Air & Moisture, Air Leakage

Glossary Of Building Science Terms
I know I’ve mentioned this section of the Building Science Corporation site before but I included it again because it gives you simple explanations of common “barrier” related terms.

Heat Air & Moisture Interactions (PDF FILE)
This IRC Construction Practice report gives an overview of heat, air and moisture movement. Included is a chart of the different types of barriers used to control the different forces.

Sources Of Air Leakage
Here is an easy-to-read pie chart from Oikos showing the average amount of air leakage from different parts of a home.

2. Air Barriers: Requirements, Permeance, Association

Air Barrier Requirements
This Canadian Building Science Insight report explains air leakage causes, and covers air barrier requirements of continuity, structural integrity, air impermeability and durability.

Air Permeance Of Building Materials
A chart showing the average air leakage rates of building materials is included in this research brief from CMHC.

Canadian Trade Association
The National Air Barrier Association is the Canadian trade association for the growing air barrier industry.

3. Air Barrier Products: ADA, Foam, Caulks & Sealants

ADA: Airtight Drywall Approach
Here are some great details from BSC for air sealing different parts of a house using the ADA approach.

Urethane Foams & Air Leakage Control
Home Energy magazine carried this article that explains the different types of foams, where and when to use them, tips for applying them, and some codes and standards issues.

Caulks & Sealants
Here is an excellent chart from Canadian Wood Council to help you select the proper product. It lists uses & materials, joint widths, costs, life spans, advantages and disadvantages.

4. Weather Barriers: Choosing, Installing, Test Results

How To Choose Weather Resistive Barriers
Here is a good report from NAHB to help you select the right product for your application. It includes benefits, drawbacks and suggested applications for each material.

Selecting & Installing Weather Resistive Barriers (PDF FILE)
This Technology Fact Sheet from DOE covers types, costs, uses, properties, and has drawings of installation details.

Testing Housewraps & Felts
This article from the University of Massechusetts is on housewraps, felt paper and penetration barriers. It explains different products and compares their test results.

5. Vapour Barriers: Yes? No? Maybe? The Debate Goes On

Different Opinions
There are differing opinions about whether or not a poly vapour barrier should be used in coastal BC. Here are a couple of links to help you better understand the debate.

From 1960: Select It Correctly
This older Canadian Building Digest report explains vapour barriers for exterior walls, ceilings and roofs. It emphasizes selecting the right material for the application.

Keep It
This report from Mark Lawton and William Brown from Building Envelope Forum discusses vapour barriers in temperate climates. It supports keeping the vapour barrier.

Its Not “The” Answer
Dr. Joe Lstiburek challenges the use of polyethylene vapour barrier on the inside of buildings as the answer to all moisture problems in this article on air barriers vs. vapour barriers.

6. Vapour Barriers: Standards, Types & Placement, Smart

Performance Standards
The Canadian Wood Council site has a brief explanation of the performance standards for vapour barriers, along with a chart showing the permeance of various building materials.

Types & Placement (PDF FILE)
This Insulation Contractors Association of America site provides an overview of the use, types, and placement of vapor retarders.

Smart Vapour Retarder
As this article from Building Online explains, there is a new type of vapour retarder for use in mixed climates (coastal BC) that changes its permeability based on the relative humidity.

7. Other Resources: Seminar, Database, Barriers For Reno

Seminar On Moisture Control
IRC offers a review of its Building Science Insight 2003 seminar on “Effective Moisture Control For Light-Frame Walls of Low-Rise Buildings. It was a one-day seminar presented across Canada by a team of scientists of NRC-IRC.

Building Envelope Database
Concordia University has a great in-depth database of building envelope research at its site. It gives an overview of each concept and lists lots of additional links to more info.

For Renovators: Vapour Retarders & Air Barriers
The Old House website offers up a section on best practices for vapour retarders & air barriers in old work. It lists the different types, with advantages and disadvantages of each.

Dittie For Today: On Motivation
Whatever your lot in life, build something on it.

 © Copyright 2003               Ken Farrish               All Rights Reserved