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4. Since radon concentration varies from site to site, and because it cannot be
measured properly until the building is constructed, a full ASD system with suction
fans will not be required unless long-term testing demonstrates one is necessary.
Instead, the responsible contractor will only be required to install the rough-in soil
gas piping for the ASD system. This includes suction pits and piping below the floor,
as well as capped piping inside the building.
5. Long-term testing is required once construction is complete and the building is
operational. Testing must be carried out by a Canadian – National Radon
Proficiency Program (C-NRPP) certified Radon Measurement Professional for a
minimum of 91 days during the winter months, and must follow all applicable
sections in Health Canada Publication 4175, Guide for Radon Measurements in
Public Buildings (schools, hospitals, care facilities, and detention centres). If
concentration levels exceed 200 Becquerels per cubic meter (Bq/m
), a full ASD
system, including fan(s), must be installed.
6. In addition to showing the rough-in drawing details, designers may also wish to
include details showing the piping layout inside the building, fan locations and
specifications, and details on the fan warning device in the event that long-term
testing indicates that a full ASD system needs to be installed. Although some
aspects the system cannot be properly designed until a sub-slab communication
test has been performed onsite (e.g. fan size, fan flow rate, and above slab piping
diameter), submitting preliminary details will provide an opportunity for the plans
examiner to provide preliminary comments.
7. Designs that do not incorporate the two measures listed in the table above will
require a letter from the designer(s) identifying the reasoning for exclusion of that
8. Designs that deviate from the applicable requirements will require a letter from the
designer(s) stating that the proposed level of performance will meet or exceed that
required in the Ontario Building Code and/or EPA/625/R-92/016, and shall list the
standard and/or guideline that was used. Designers will be notified if a formal
Application for an Alternative Solution is required after the permit application has
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Personal information contained in this form and schedules is collected under the authority
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