(The provisions contained in this appendix are not mandatory unless specifically referenced in the adopting ordinance.)
EPA MAP OF RADON ZONES
apCi/L standard for picocuries per liter of radon gas. The U.S. environmental protection agency (EPA) recommends that all homes that measure 4 pCi/L and greater be mitigated.
The EPA and the U.S. geological survey have evaluated the radon potential in the U.S. and have developed a map of radon zones designed to assist building officials in deciding whether radon resistant features are applicable in new construction.
The map assigns each of the 83 counties in Michigan to 1 of 3 zones based on radon potential. Each zone designation reflects the average short-term radon measurement that can be expected to be measured in a building without the implementation of radon-control methods. The radon zone designation of highest priority is zone 1. Table AF101 lists the zone 1 counties illustrated on the map. More detailed information can be obtained from state-specific booklets (EPA-402-R-93-021 through 070) available through state radon offices or from EPA regional offices.
R 408.30547a| Branch |
| Calhoun |
| Cass |
| Hillsdale |
| Jackson |
| Kalamazoo |
| Lenawee |
| St. Joseph |
| Washtenaw |
- The EPA recommends that this county listing be supplemented with other available state and local data to further understand the radon potential of a zone 1 area.
This appendix contains requirements for
new construction in jurisdictions where radon-resistant construction
is required. These requirements are intended to provide
a passive means of resisting radon gas entry and prepare
the dwelling for post-construction radon mitigation, if necessary
(see Figure AF102). Active construction techniques,
rather than passive techniques, shall be permitted to be used
where approved.
Inclusion of this appendix by jurisdictions shall be determined through the use of locally available data or determination of Zone 1 designation in Figure AF101 and Table AF101(1).
Inclusion of this appendix by jurisdictions shall be determined through the use of locally available data or determination of Zone 1 designation in Figure AF101 and Table AF101(1).
For the purpose of these requirements, the
terms used shall be defined as follows:
DRAIN TILE LOOP. A continuous length of drain tile or perforated pipe extending around all or part of the internal or external perimeter of a basement or crawl space footing.
ENCLOSED CRAWL SPACE. A crawl space that is enclosed with foundation walls inclusive of any windows, doors, access openings and required vents.
GAS-PERMEABLE LAYER. A gas-permeable layer shall consist of one of the following:
RADON GAS. A naturally occurring, chemically inert, radioactive gas.
SOIL-GAS-RETARDER. A continuous membrane of 6-mil (0.15 mm) polyethylene used to retard the flow of soil gases into a dwelling.
SUBMEMBRANE DEPRESSURIZATION SYSTEM. A system designed to achieve lower submembrane air pressure relative to basement or crawl space air pressure by use of a vent drawing air from beneath the soil-gas-retarder membrane.
SUBSLAB DEPRESSURIZATION SYSTEM (Passive). A system designed to achieve lower subslab air pressure relative to indoor air pressure by use of a vent pipe drawing air from beneath concrete floor slabs or other floor assemblies that are in contact with the ground.
VENT PIPE. Not less than a 3-inch-diameter (76 mm) ABS or PVC gas-tight pipe extending from the gas permeable layer through the roof.
DRAIN TILE LOOP. A continuous length of drain tile or perforated pipe extending around all or part of the internal or external perimeter of a basement or crawl space footing.
ENCLOSED CRAWL SPACE. A crawl space that is enclosed with foundation walls inclusive of any windows, doors, access openings and required vents.
GAS-PERMEABLE LAYER. A gas-permeable layer shall consist of one of the following:
- A uniform layer of clean aggregate that is not less than 4 inches (102 mm) thick. The aggregate shall consist of material that will pass through a 2-inch (51 mm) sieve and be retained by a 1/4-inch (6.4 mm) sieve.
- A uniform layer of sand (native or fill) that is not less than 4 inches (102 mm) thick and that is overlain by a soil gas collection mat or soil gas matting installed in accordance with the manufacturer's instructions.
RADON GAS. A naturally occurring, chemically inert, radioactive gas.
SOIL-GAS-RETARDER. A continuous membrane of 6-mil (0.15 mm) polyethylene used to retard the flow of soil gases into a dwelling.
SUBMEMBRANE DEPRESSURIZATION SYSTEM. A system designed to achieve lower submembrane air pressure relative to basement or crawl space air pressure by use of a vent drawing air from beneath the soil-gas-retarder membrane.
SUBSLAB DEPRESSURIZATION SYSTEM (Passive). A system designed to achieve lower subslab air pressure relative to indoor air pressure by use of a vent pipe drawing air from beneath concrete floor slabs or other floor assemblies that are in contact with the ground.
VENT PIPE. Not less than a 3-inch-diameter (76 mm) ABS or PVC gas-tight pipe extending from the gas permeable layer through the roof.
The following components of a passive
submembrane or subslab depressurization system shall be
installed during construction.
Potential radon entry routes shall be
closed in accordance with Sections AF103.2.1 through
AF103.2.8.
Sumps open to soil or serving as the
termination point for subslab or exterior drain tile loops
shall be covered with a gasketed or sealed lid. Sumps used
as the suction point in a subslab depressurization system
shall have a lid designed to accommodate the vent pipe.
Sumps used as a floor drain shall have a lid equipped with
a trapped inlet.
Hollow block masonry
foundation walls shall be constructed with a continuous
course of solid masonry, one course of masonry grouted
solid, or a solid concrete beam at or above grade. Where a
brick veneer or other masonry ledge is installed, the course
immediately below that ledge shall be solid masonry, one
course of masonry grouted solid, or a solid concrete beam.
Joints, cracks or other openings around penetrations of
both exterior and interior surfaces of foundation walls
below grade shall be filled with polyurethane caulk.
The exterior surfaces of foundation
walls below grade shall be dampproofed in accordance
with Section R406.
Entry points, joints
or other openings into air-conditioning systems in
enclosed crawl spaces shall be sealed.
Exception: Systems with gasketed seams or that are
otherwise sealed by the manufacturer.
Ductwork passing through or beneath a
slab within a dwelling shall be of seamless material unless
the air-conditioning system is designed to maintain continuous
positive pressure within such ducting. Joints in such
ductwork shall be sealed.
Ductwork located in enclosed crawl spaces shall have seams and joints sealed by closure systems in accordance with Section M1601.4.1.
Ductwork located in enclosed crawl spaces shall have seams and joints sealed by closure systems in accordance with Section M1601.4.1.
In dwellings with basements or enclosed crawl spaces
with soil floors, the following components of a passive submembrane
depressurization system shall be installed during
construction.
Exception: Basements or enclosed crawl spaces that are
provided with a continuously operated mechanical exhaust
system in accordance with Section R408.3.
The soil in basements and
enclosed crawl spaces shall be covered with a soil-gasretarder.
The soil-gas-retarder shall be lapped not less than
12 inches (305 mm) at joints and shall extend to foundation
walls enclosing the basement or crawl space. The soilgas-
retarder shall fit closely around any pipe, wire or other
penetrations of the material. Punctures or tears in the
material shall be sealed or covered with additional sheeting.
A 3- or 4-inch "T"
fitting shall be inserted beneath the soil-gas-retarder and
be connected to a vent pipe. The vent pipe shall extend
through the conditioned space of the dwelling and terminate
not less than 12 inches (305 mm) above the roof in a
location not less than 10 feet (3048 mm) away from any
window or other opening into the conditioned spaces of
the building that is less than 2 feet (610 mm) below the
exhaust point.
A soil-gas-retarder shall be
placed on top of the gas-permeable layer prior to casting the slab or placing the floor assembly. The soil-gasretarder
shall cover the entire floor area with separate sections
lapped not less than 12 inches (305 mm). The soilgas-
retarder shall fit closely around any pipe, wire, or
other penetrations of the material. Punctures or tears in the
material shall be sealed or covered.
Before a slab is cast
or other floor system is installed, a "T" fitting shall be
inserted below the slab or other floor system and the soilgas-
retarder. The "T" fitting shall be connected to a vent
pipe. The vent pipe shall extend through the conditioned
space of the dwelling and terminate not less than 12 inches
(305 mm) above the roof in a location not less than 10 feet
(3048 mm) away from any window or other opening into
the conditioned spaces of the building that is less than 2
feet (610 mm) below the exhaust point.
In dwellings where interior
footings or other barriers separate the gas-permeable layer,
each area shall be fitted with an individual vent pipe. Vent
pipes shall connect to a single vent that terminates above the
roof or each individual vent pipe shall terminate separately
above the roof.
Where basement or
crawl space floors are on different levels, each level shall
have a separate vent pipe. Multiple vent pipes shall be permitted
to be connected to a single vent pipe that terminates above
the roof.
Components of the radon vent
pipe system shall be installed to provide positive drainage to
the ground beneath the soil-gas-retarder.
Exposed and visible interior
vent pipes shall be identified with not less than one label
on each floor and in accessible attics. The label shall read:
"Radon Reduction System."
To provide for future installation of a radon fan, an electrical
circuit terminated in an approved box shall be installed during
construction in the anticipated location of the radon fans.
An accessible clear space 24 inches (610 mm) in diameter by
3 feet (914 mm) in height adjacent to the vent pipe shall be
provided at the anticipated location of a future radon fan.