- active
soil-depressurization system: one or more of the following types of
radon mitigation system types involving mechanically driven soil
depressurization: sub-slab depressurization; sump (pit) depressurization;
drain-tile depressurization; sub-membrane depressurization; hollow-block wall
depressurization; and crawlspace depressurization.
- crawlspace
depressurization: an active radon-mitigation system that lowers
the
air pressure inside a crawlspace in relation to the rooms adjacent to or
above the crawlspace. A fan draws air directly from the air space of
the crawlspace and discharges it outside. This type of system is not the
best choice because of the great potential for appliance
back-drafting and energy loss.
- defect: a
condition of a radon mitigation system that may have an adverse impact on
its performance.
- depressurization: a
negative pressure created in one area compared to an adjacent area.
- discharge: the end of a vent stack pipe open to outside air.
- drain-tile
depressurization: an active soil-depressurization system whereby a
suction point is located at a drain tile.
- heat-recovery
ventilation (HRV) system: a system that lowers radon levels by
using outside air to dilute and pressurize the indoor air. HRV systems are
considered active radon mitigation systems.
- hollow-block
wall depressurization: an active radon mitigation system that
depressurizes the open spaces within concrete block foundation walls.
- inspection: a
non-invasive, visual examination of a radon mitigation system.
- manifold
pipe: a pipe between a vent stack pipe and suction-point pipe
with two or more suction points.
- radon mitigation
system: any system designed to reduce the radon concentrations of
indoor air.
- radon
system piping: the piping of a passive or active radon mitigation
system that is composed of a suction-point pipe, manifold pipe, and vent stack
pipe.
- readily
accessible: a system or component that is, in the judgment of the
inspector, capable of being safely observed without the removal of obstacles,
detachment, or disengagement of connecting or securing devices, or other unsafe
or difficult procedures in order to gain access.
- sub-membrane
depressurization: an active radon mitigation system that creates low air pressure under a vapor retarder. A common example is when a vapor
retarder (polyethylene plastic sheet) is installed over the exposed dirt floor
of a crawlspace. The radon fan draws air from below the vapor retarder
and sends it outside.
- sub-slab
depressurization (active): a radon mitigation system that
creates low air pressure under a concrete floor using a fan.
- sub-slab
depressurization (passive): a radon mitigation system that
creates low air pressure under a concrete floor without the use of a fan.
- suction
point: the end of a radon mitigation system that penetrates the slab,
wall, vapor barrier, sump cover, or drain tile.
- sump
(pit) depressurization system (active): a radon mitigation
system that has a suction point installed in the sump (pit).
- vent
stack pipe: a pipe leading from the suction point (in a system with a
single suction point) or the manifold pipe (in a system with more than one
suction point) to the outside air. In active radon mitigation systems, the
radon fan is installed vertically in the vent stack pipe.
Goal
of Inspection
The goal of the inspection is to provide observations that may
indicate that a radon mitigation system was installed improperly, is not
performing as designed, or is in need of repair.
Limitations
The inspection is
limited to readily accessible and visible portions of the radon mitigation
system. The inspection should not be considered all-inclusive
or technically exhaustive. It is not a substitute for a radon level
measurement.
This standard
does not require the inspector to:
- inspect
any portion of the system that is not readily accessible and visible.
- activate
a system that has been turned off, unplugged, or deactivated.
- measure
the radon level.
Optional
Add-On Inspection Service
Although InterNACHI's Standards of Practice for Inspecting
Commercial Properties and InterNACHI’s Home Inspection Standards of Practice do not require the inspector to
perform radon mitigation system inspections, one may be offered in
conjunction with a complete commercial or residential property inspection, or
as a separate, stand-alone inspection service.
VISUAL INSPECTION
Radon Mitigation System
Type
The inspector shall
describe the radon mitigation system as one of the following types:
- active
sub-slab depressurization;
- passive
sub-slab depressurization;
- sump
(pit) depressurization;
- drain-tile
depressurization;
- sub-membrane
depressurization;
- hollow-block
wall depressurization;
- crawlspace
depressurization; or
- heat-recovery
ventilation.
Drain-Tile Depressurization
Systems
The inspector should inspect
drainpipes that extend to daylight for missing devices, such as one-way flow
valves, or water traps that prevent outdoor air from entering the sub-slab
area.
Sub-Membrane
Depressurization Systems
The inspector should inspect the
vapor retarder used for sub-membrane depressurization systems (passive or
active) for seams that are lapped less than 12 inches, and edges that are
not sealed to the walls, posts, or other penetrations.
Hollow-Block Wall
Depressurization Systems
The inspector should inspect
hollow-block walls for cracks, openings, and open top-courses.
Crawlspace
Depressurization Systems
The inspector should inspect the
crawlspace for the presence of asbestos-like material and combustible
fuel-served appliances located within the crawlspace or in spaces adjacent to the
crawlspace.
Heat-Recovery
Ventilation (HRV) Systems
The inspector should inspect the
area around the HRV system for the presence of asbestos-like material.
Piping and Fittings
The inspector should inspect for:
- penetrations of pipes or ducts that penetrate a
firewall or other fire resistance-rated wall or floor not protected in
accordance with applicable building, mechanical, fire, or electrical codes;
- submersible pumps not used in systems that use
sump pits as the suction point for active soil depressurization if sump pumps
are needed;
- joints and connections that are not permanently
sealed with adhesives;
- joints and connections that are not airtight;
- attic and external runs subject to sub-freezing that are not protected to prevent the risk of vent pipe freeze-up;
- piping that is not PVC, ABS, or downspout
(outside);
- piping subjected to weather or physical damage
that is not Schedule 40;
- pipe and fitting connections of different
materials;
- piping that isn’t solid and rigid;
- reducers that are installed in the direction of
air flow;
- radon vent pipes blocking access to any areas
requiring maintenance or inspection;
- radon vent pipes not designed with removable or
flexible couplings to facilitate removal of the sump pit cover for sump pump
maintenance;
- radon vent pipes not installed in a
configuration that ensures that any rain water or condensation within the pipes
drains downward into the ground beneath the slab or soil-gas retarder membrane; and
- a missing one-way flow valve, water trap, or
other control device installed in or on the discharge line to prevent outside
air from entering the system while allowing water to flow out of the system
when a radon mitigation system is designed to draw soil gas from a perimeter
drain tile loop that discharges water through a drain line to daylight or to a
soak-away.
Piping Supports
The inspector shall inspect for:
- hangers, strapping, or other supports that
inadequately secure the vent material;
- existing plumbing pipes, ducts, or mechanical
equipment used to support or secure a radon vent pipe;
- supports installed more than 6 feet apart on
horizontal runs;
- supports installed more than 8 feet apart on vertical
runs; and
- pipes not supported or not secured in a
permanent manner so as to prevent their downward movement to the bottom of suction
pits or sump pits, or into the soil beneath an aggregate layer under a slab to
prevent blockage of air flow into the bottom of the radon vent pipes.
Materials
The
inspector shall inspect for:
- vent pipes not made of Schedule 20 PVC, ABS, or
equivalent;
- vent pipes used in garages and in other internal
and external locations subject to weathering or physical damage not made of
Schedule 40 piping or its equivalent;
- vent pipe fittings in a mitigation system that
are not of the same material as the vent pipes;
- cleaning solvents and adhesives to join plastic
pipes and fittings that are not recommended by the manufacturers of the pipe
material;
- improperly used caulks and sealants at any
cracks in slabs or other openings around penetrations of the slab and
foundation walls;
- non-shrink mortar, grout, or expanding foam not
being used when sealing holes for plumbing rough-in or other large openings in
slabs and foundation walls that are below the ground surface;
- sump pit covers not made of durable plastic;
- sump pit covers not providing an airtight seal;
- penetrations of sump covers that are not airtight;
- plastic sheeting installed in crawlspaces as
soil-gas retarders that are not a minimum of 6-mil polyethylene or equivalent
material; and
- any wood used in attaching soil-gas retarder
membranes to walls or piers not pressure-treated or naturally resistant to
decay and termites.
Point of Discharge for Fan-Powered Soil
Depressurization and Block-Wall Depressurization Systems
The inspector should inspect for:
- the point of discharge being below the eaves of
the roof;
- the point of discharge being less than 10 feet
above ground level;
- the point of discharge being less than 10 feet away from any window,
door, or other opening into conditioned spaces of the structure
that is less than 2 feet below the exhaust point; and
- the point of discharge being less than 10 feet away from any opening into an adjacent building.
Radon Fan
The inspector should inspect for:
- radon fans not designed or not sealed to reduce
the potential for leakage of soil gas from the fan housing;
- radon fans not sized to provide the pressure
difference and air flow characteristics necessary to achieve the
radon reduction goals established;
- radon fans installed in the conditioned space of a
building, in any basement, crawlspace, or other interior location directly
beneath the conditioned spaces of a building;
- radon fans installed in attics that are suitable
for occupancy;
- radon fans installed in attached garages beneath
conditioned spaces;
- radon fans installed underground;
- radon fans installed in a configuration that
allows condensation to build up in the fan housing;
- radon fans that are not mounted vertically;
- radon fans mounted on the exterior of buildings
that are not rated for outdoor use or not installed in a watertight protective
housing;
- radon fans that are not mounted and secured in a
manner that minimizes transfer of vibration to the structural framing of the
building;
- radon fans that are not installed using
removable couplings or flexible connections to facilitate maintenance and
future replacement; and
- radon fans used in crawlspace pressurization or
building pressurization that do not have removable screens or filters on the
fan intakes to prevent ingestion of debris or personal injury.
Suction Pit for Sub-Slab Depressurization
Systems
The inspector should inspect for:
- an inadequate amount of excavated material from the
area immediately below the slab penetration point of the system’s vent pipes.
Sealing
The inspector should inspect for:
- uncovered or unsealed sump pits that permit
entry of soil gas or that would allow conditioned air to be drawn into a
sub-slab depressurization system;
- openings around radon vent pipe penetrations of
the slab, foundation wall, or crawlspace soil-gas retarder membrane that are
not cleaned, prepared and sealed in a permanent, airtight manner;
- open or unsealed openings in the tops of walls
and all accessible openings or cracks in the interior surfaces of the walls,
where a block-wall depressurization system is used to mitigate radon;
- openings, perimeter channel drains, or cracks
where the slab meets the foundation wall that are not sealed;
- seams and joints in the baseboard of
baseboard-type suction systems that are not joined and not sealed;
- seams in soil-gas retarder membranes used in
sub-membrane depressurization system that are not overlapped at least 12 inches
and not sealed;
- open and unsealed access doors and other
openings between the basement and the adjacent crawlspace where the crawlspace
has been confirmed as a source of radon entry; and
- open and unsealed openings and cracks in floors
above the crawlspace that would permit conditioned air to pass out of the
living spaces when crawlspace depressurization is used.
Electrical
The inspector should inspect for:
- wiring that does not conform to provisions of the
National Electrical Code (NEC) and local building codes;
- wiring located in or chased through ducting;
- cord and plug assemblies supplying power to
radon fans that are more than 6 feet in length;
- cord and plug assemblies supplying power to
radon fans that pass through walls, floors or ceilings, or that are concealed within
building components;
- radon fans installed on the exterior of the building
that are not hard-wired into an electrical circuit;
- radon fans used outdoors that are plugged;
- a missing electrical disconnect switch or a missing
circuit breaker for radon mitigation system fan circuits;
- a means of disconnect not in sight of its radon
fan;
- missing grounded receptacles (required within 6
feet of radon fans installed under roofs);
- missing GFCI receptacles (required within 6 feet
of radon fans installed above roofs); and
- missing electrical junction boxes (required
within 6 feet of radon fan locations of both active and passive systems).
Drain
The inspector should inspect for:
- condensate drainpipes that are not directed into
condensate pumps, not directed into trapped floor drains, or do not have 6-inch
or greater standing water-trap seals;
- unsealed perimeter (channel or French) drains; and
- a sump pit (used for protection or relief from
excess surface water) that has a cover not recessed and not fitted with a
trapped drain.
HVAC
The inspector should inspect for:
- modifications to an
existing HVAC system proposed to mitigate elevated levels of radon that are
reviewed and approved by a qualified contractor;
- foundation vents (used to
reduce indoor radon levels by increasing natural ventilation) that are
closable;
- heat-recovery ventilation (HRV) systems that are installed in rooms that contain friable asbestos;
- supply and exhaust ports
of heat-recovery ventilation systems installed less than 12 feet apart;
and
- confirmation by the
contractor that the incoming and outgoing flow from heat-recovery
ventilation systems are balanced.
Monitoring and Labeling
The inspector should inspect for:
- a missing mechanism to
monitor performance of an active soil depressurization system and
block-wall depressurization system and to warn of system failure;
- electrical radon mitigation
system monitors installed on switched circuits;
- electrical
radon mitigation system monitors not designed to re-set automatically when
power is restored after failure;
- manometer-type pressure
gauges not clearly marked to indicate the range of pressure readings that
existed when the system was initially activated;
- a missing system
description label placed on the mitigation system;
- a missing system
description label placed on the electric service entrance panel;
- a system description
label that is not legible from at least 3 feet away;
- a system description
label that does not include all of the following information:
- “Radon Reduction
System”;
- the installer’s name and contact information;
- the date
of the installation; and
- an advisory that the building should be tested
for radon at least every two years;
- a missing system
description label on each floor level of all exposed and visible interior
radon mitigation system vent-pipe sections reading “Radon Reduction
System”;
- missing identification of
the circuit breaker controlling the circuit on which the radon vent fan
and system-failure warning devices operate; and
- missing labels on the plastic vapor barrier (if
installed).
Sample inspection report for radon mitigation systems
Other inspection checklists.
