2/5/2018 Radon control options for new home construction William J. Angell, Professor University of Minnesota June 2017 SPONSORED BY WISCONSIN DEPARTMENT OF HEALTH SERVICES Sources ANSI/AARST 2013. Reducing Radon in New Construction: 1 & 2 Family Dwellings and Townhouses (RRNC 2.0 standard), Hendersonville, NC: American Association of Radon Scientists and Technologists. Also see: Angell, WJ 2012. Radon Control in New Homes: A Meta- Analysis of 25 Years of Research , Proceeding of the 2012 International Radon Symposium , Las Vegas, NV: American Association of Radon Scientists and Technologists. 1
2/5/2018 Key concepts Why is effective radon control in new 1 homes important? What are the basic options for radon 2 control? 3 What are the critical components of radon control? Who should install radon control systems? 4 Why is a performance test essential? 5 Importance of radon control Radon exposure in homes leads to 25,000 lung cancer deaths in the U.S. each year ...far more deaths than those caused by residential fires and carbon monoxide . 2
2/5/2018 Importance of radon control New homes typically have higher radon concentrations compared to older homes …especially true with air exchange rates under 0.3 ACH. Most cost-effective way to reduce radon induced lung cancer. Importance of radon control Importance of radon control For 30 years , many agencies have recommended radon control in new homes. 3
2/5/2018 Importance of radon control Properly installed, radon control can reduce call-backs and liability . It tells the community that you care about resident health and safety . 4
2/5/2018 Basic options for radon control in your homes Passive systems (without a fan) � 25 year track record � Specified by IRC Appendix F � Depends on a 3–4” vent providing more suction than the house… a tough challenge � If all details are effectively executed , there may be about a 55% reduction in indoor radon concentrations � Most builder-installed systems have errors that reduce system effectiveness Basic options for radon control in your homes Active systems (with fan) � About 2 million systems installed 30+ years � Specified in ANSI/AARST RRNC 2.0 standard � Commonly uses a small wattage, in-line radon fan (14 to 40 watts) � More forgiving with normal construction errors � Typically, reduces indoor radon concentrations 90 to 99%… the greatest radon reduction 5
2/5/2018 Critical components of radon control systems Permeable layer Specific vent pipe under slab type, size and routing Air-tight soil gas Fan or no fan retarder and slab Critical components of radon control systems Permeable layer under slab under all soil contacted areas (also known as soil gas collection plenum ) Commonly, a minimum of 4” of clean aggregate with a minimum of 35% void ratio or size number 4, 5, 56, or 6 (ASTM C33) OR may be geotextile drain matting � In crawl spaces, a minimum of 10’ strips, 12” wide � Under concrete floors, 12” wide strips placed 12–18” from perimeter � Or may be a continuous loop of 4” perforated pipe placed 12–18” from perimeter and backfilled with clean aggregate 6
2/5/2018 Critical components of radon control systems Air-tight soil gas retarder and slab A soil gas retarder must cover the top of the soil gas plenum. In crawl spaces , the retarder must cover exposed soil. Critical components of radon control systems Air-tight soil gas retarder and slab Under slabs , polyethylene sheeting must be installed over the plenum � If cross-laminated, a minimum of 3 mils thickness � If not cross-laminated, a minimum of 6 mils thickness 7
2/5/2018 Critical components of radon control systems Air-tight soil gas retarder and slab In crawl spaces , the membrane must meet ASTM E1745 Class A, B or C Critical components of radon control systems Air-tight soil gas retarder and slab (continued) In all cases, the soil gas retarder: � Must be overlapped and sealed with manufacture-recommended tape or caulk � Must seal all tears and punctures with manufacture-recommended tape or caulk � Must seal penetrations with ASTM C920 Class 25 or higher caulk or an equivalent method 8
2/5/2018 Critical components of radon control systems Air-tight soil gas retarder and slab (continued) In all cases, the soil gas retarder: � Must turn the membrane edge up the foundation wall at least 6" and continuously seal it with caulk complying with ASTM C920 Class 25 � In slabs , plumbing block-outs must be filled with expanding foam, a non-shrink grout or other appropriate method (If the opening is exposed, seal with a non-shrink grout or equivalent method) Critical components of radon control systems Air-tight soil gas retarder and slab (continued) Where foundation walls are concrete , the soil gas retarder must be sealed to the foundation wall or the footing Where foundation walls are masonry block , the soil gas retarder must be sealed to the foundation wall or the footing 9
2/5/2018 Critical components of radon control systems Air-tight soil gas retarder and slab (continued) The intersection of floors and foundation walls must be sealed with a caulk complying with ASTM C920 Class 25 or higher or equivalent Sumps in indoor floors shall have a rigid lid which must be sealed with a gasket or silicone caulk and be mechanically fastened Critical components of radon control systems Vent pipe � Must be rigid, non-perforated Schedule 40 and not less than 3” ID � Must have a slope towards the suction point of not less than 1/8” per foot � Must prepare plastic pipe joints with a primer and solvent welded � Supports for horizontal pipe shall not exceed 4’ and supports for vertical pipe must not exceed 10’ � Must be labeled at each floor level and at intervals not greater than 10’ along the length of the pipe 10
2/5/2018 Critical components of radon control systems Vent pipe—suction points � Suction points must be installed in each soil gas collection plenum as well as provided for each foundation type � The bottom of the vent pipe must have not less than 2 openings in soil gas collection plenum (for example, a “T” fitting) Critical components of radon control systems Vent pipe—suction points � In an aggregate-filled soil gas plenum, the vent pipe connector must have not less than 5’ of perforated pipe extending from each opening � Suction points are not permitted through sump lids � Suction points must be fastened to prevent dislocation 11
2/5/2018 Critical components of radon control systems Critical components of radon control systems Vent pipe location—provision for a fan � If located in an attic, access entry must not be greater than 20’ from the fan’s location � Must provide space with a vertical height of at least 48” and a diameter of at least 21” in the area where radon fan will be installed � An electrical boxed receptacle shall be located within 6’ of the fan (If the fan will not be a cord/plugged connected, a means for disconnect shall be in sight of the fan) Critical components of radon control systems Vent pipe—discharge Must be: � discharged outdoors and directed vertically upward � at least 12” above the roof at the point of discharge � at least 10’ above grade at the point of discharge � at least 2’ above or 10’ from windows, doors, or other openings into the home or adjacent homes 12
2/5/2018 Critical components of radon control systems Active soil depressurization (ASD) fan installation � Unless a pre-occupancy radon test result is less than 4 pCi/L, a radon fan must be installed � The fan must be located outdoors and/or above the conditioned space � Additional labeling is required on the vent pipe and within 12” of the electrical service panel (See ANSI/AARST RRNC 2.0 for specifics) � The fan must be specified for use in mitigation Critical components of radon control systems ASD fan selection ANSI/AARST RRNC 2.0 specifies fan sizing depending on the pipe diameter and total foundation area Foundation area Vent pipe Radon fan minimum rating < 1,600 ft 2 50 cfm @ 0.5” WC 1,600–2,500 ft 2 3” diameter 75 cfm @ 0.5” WC 1,600–2,500 ft 2 4” diameter 50 cfm @ 0.5” WC > 2,500 ft 2 fan must be sized by a certified or licensed radon mitigator 13
2/5/2018 Critical components of radon control systems Fan installation � Must be installed only on vertical pipe � Must be connected to the vent pipe with flexible connectors � Must be energized upon installation Critical components of radon control systems Monitoring � Each ASD system must have an air pressure indicator, such as a U-tube manometer , that is readily observable by occupants � Upon fan start-up, the monitor air pressure must be clearly marked � If the monitor is electrically activated, power must be from an unswitched circuit and, after power failure, automatically reset when power is restored 14
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