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Building Radon Out
Zone 3
Counties have a predicted average
indoor screening level less than
2 pCi/L
Elevated radon have been found in all
counties (Zone 1, Zone 2 and Zone 3).
Model Codes
Documents specifying requirements for
building, mechanical, plumbing, and
fire prevention installations. Often the
basis for state and local building
codes.
Model Standard
A document that has been developed
and established to connote specified
consensus and approval of certain
techniques and standards. A prescribed
level of acceptability or an approved
model used as a basis for comparison.
Voluntary technical guidance until
adopted into a building code. EPA has
published one for radon-resistant new
construction, called Model Standards
and Techniques for Control of Radon in
New Residential Buildings.
Passive System
Short for passive sub-slab
depressurization system. Features to
reduce radon levels by utilizing barriers
to radon entry and stack effect
reduction techniques and the
installation of a PVC pipe running from
beneath the slab to the roof. Works by
using natural pressure differentials
between the air in the pipe, and the
rest of the home and the outside air.
Picocuries per liter (pCi/L)
A unit of measuring radon levels.
Polyethylene Sheeting
(used as soil-gas-retarder)
Plastic sheeting, about drop cloth
weight, used over gravel and under the
concrete slab to prevent soil gases from
entering a home. The sheeting also
prevents the concrete from flowing into
the gravel and blocking air flow beneath
the slab. Also used as a moisture
barrier.
PVC Pipe
A hollow plastic pipe generally used for
plumbing in home construction.
Slab
The concrete floor poured over the
ground between the foundation walls,
either at ground floor or basement
level.
Soil Gas
Any gas emanating from the soil,
including radon, methane, and water
vapor.
Stack Effect Reduction Techniques
Features that prevent or reduce the
flow of warm conditioned air upward and
out of the building superstructure. If
not reduced, stack effect can actually
draw soil gas containing radon into the
lower levels of the house. Most of
these techniques are part of the
International Code Councils Model
Energy Code.
Sub-Membrane Depressurization
A system designed to achieve lower
sub-membrane air pressure relative to
crawlspace air pressure by use of a vent
drawing air from beneath the soil-gas
retarder membrane. May be a passive
system (without fan) or active system
(with fan).
Sub-Slab Depressurization
A system designed to achieve lower
sub-slab air pressure relative to indoor
air pressure. May be a passive system
(no fan) or active system (with fan).
Sump / Sump pit
A hole going below the slab into which
water is drained in order to be pumped
out. Should be sealed to prevent
radon from entering the home.