Civil Engineering Reference
In-Depth Information
3 Protection Measures
In the UK, new properties must be fitted with a sump if more than 10 % of the
existing properties in an area show readings above the action level. A fan can then
be added if subsequent tests reveal that one is needed to further reduce radon
levels. Regulations now require that a radon-proof membrane designed to prevent
radon entering a property should be installed in new houses built in areas of the
UK where 3 % or more of existing properties are above the action level (BRE
1999
).
Since 1995, Czech Republic buildings located in radon prone areas must have
water proofing membranes placed over the entire surface of the floors and base-
ment walls in contact with the soil. Recent recommendations emphasize that all
new homes in England and Wales, regardless of location, be built with radon-proof
membranes (Environmental Radon Newsletter
2008
).
Some authors (Jiranek and Hulka
2001
; Rovenska and Jiranek
2012
) mention
that the correct selection of both the type and minimal thickness of radon-proof
membranes is difficult just because they are influenced by the building and soil
characteristics.
The WHO Handbook (
2009
) summarizes the protection measures as follows:
(a) Active soil depressurization
(b) Passive soil depressurization
(c) Sealing of surfaces
(d) Barriers and membranes
(e) Ventilation of unoccupied spaces
(f) Ventilation of occupied spaces.
Analyses of different measures show that active sub-slab depressurization
systems usually are the most effective preventive measure as a stand-alone solu-
tion, assuming an airtight construction (Jelle
2012
).
Several studies (Synnott et al.
2004
; Denman et al.
2005a
) have already dem-
onstrated that radon-proof membranes have a significant failure rate. This leads to
new homes in which radon levels are above the action level. Therefore, it is
important to ensure satisfactory airtightness in the radon barrier toward the
building ground, e.g., by avoiding perforations and ensuring sufficient airtightness
in joints and feedthroughs.
Different authors address several design details concerning protection measures
to reduce indoor radon concentration. Figure
1
shows details for the protection of a
suspended concrete floor and also of a ground bearing concrete floor slab.
Arvela (
2001
) gives details on the use of bitumen felt and elastic sealants to
achieve air tightness (Fig.
2
a) and also the installation of a perforated pipe to
reduce radon pressure (Fig.
2
b).
Those authors compared the effectiveness of different protection measures in
order to reduce indoor radon concentration (Table
3
). They stated that sub-slab
piping with an operating fan provides an efficient preventive measure. They also
