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Reducing Radon Levels in Existing Homes Guide

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Reducing Radon Levels in Existing Homes:

A Canadian Guide for Professional Contractors



Chapter 1 – An Overview of Radon

1.1 What is Radon?

1.2 Why is it a Health Hazard?

1.3 Radon Guideline


Chapter 2 – Confirming the Radon Test was Carried Out Properly

2.1 Introduction

2.2 Health Canada Testing Guidance

      Long-Term Measurements

      Short-Term Measurements


Chapter 3 – An Overview of Radon Reduction Systems

3.1 How Does Radon Enter a Home?

3.2 Principles of Reducing Radon Entry

3.3 Selection of Mitigation Methods

3.4 Masonry Foundations

3.5 Hollow Concrete Block Foundations

3.6 Poured Concrete Foundations

3.7 Slab-on-Grade Foundations

3.8 Seasonal Effects

3.9 Summary of Mitigation Options


Chapter 4 – Mitigation by Sub-Slab Depressurisation

4.1 Introduction

4.2 Feasibility Test

      Feasibility Test Example

4.3 System Design


      Building Pressure Differences

      Fan Flow Estimate

      Estimate of System Pressure Drops


      Fan Selection

      Measurements in other seasons

      Sub-slab system installation examples


Chapter 5 – Mitigation of Exposed Soil

5.1 Introduction

5.2 Sub-membrane Depressurisation

5.3 Sizing the System Fan for Sub-membrane Depressurization


Chapter 6 – Mitigation by Sump and Drainage System Depressurization

6.1 Introduction

6.2 Closing a Sump System

      Floor Drains

      Sizing the sump system fan

      Sub-slab depressurisation and sumps

6.3 Using Perimeter Foundation Drains

      Sizing the system fan

      Exterior fan installation


Chapter 7 – Mitigation by Ventilation Methods

7.1 Introduction

7.2 Exhaust Solutions

7.3 Forced Air Heating

7.4 Supply Solutions

7.5 Heat Recovery Ventilators

7.6 Sizing the Ventilation Fan

7.7 Installation


Chapter 8 – Mitigation by Closing Entry Routes

8.1 Background

8.2 Difficulties

8.3 Closing Entry Routes as part of Sub-slab Depressurisation


Chapter 9 – Fan and Piping Installation

9.1 Introduction.

9.2 Exhaust discharge location

9.3 Fan Location

9.4 Electrical Installation

9.5 Fan Monitoring

9.6 Piping

9.7 Labeling

9.8 Managing Condensation


Chapter 10 – Combining Mitigation Systems

10.1 General

10.2 Block Wall Ventilation


Chapter 11 – Building Codes and Radon Mitigation

11.1 General

11.2 Examples

        Plumbing Code

        Fire Code


Chapter 12 – Combustion Appliance Back-drafting

12.1 Carbon Monoxide

12.2 Combustion Appliances

12.3 Testing

12.4 CO detector


Chapter 13 – Post Installation Testing

13.1 System Mechanical Checks

13.2 Short term Radon Test

13.3 Long- term Radon Test

        Digital Radon Monitors

13.4 Future Radon Testing


Chapter 14 – General Safety Precautions

14.1 Health and Safety Plan


        Crawlspace/Attic Hazards





14.2 Radiation Exposure


Additional Reference Material



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