After Construction System

Transcription

1 New Home Construction Techniques After Construction System Can you spot the radon system? 1

2 HIGH LOW New Homes Can Be Built With Radon Control Systems FAN Active Passive with Fan Reduction ~50% to Reduction <2.0 or lower Make Provisions To Allow For System Activation Passive Active Appendix F Applicability One and two-family detached dwellings Separated by unobstructed space i.e., i.e., singles and duplexes Multiple, attached single-family dwellings Less Less than 4 stories and with separate means of egress i.e., i.e., townhouses Excluded: Multi-family dwellings such as apartments Approach makes sense for these structures Liability reduction Future code revisions 2

3 Treating Slabs Basement Slab-on on-grade Designed to Make Sub-Grade Porous and a Means to Collect Radon laden Soil Gas Improving Soil Gas Collection During Construction Of Slabs Four inch layer of clean aggregate beneath slab. When When gravel is incorporated for drainage or is inexpensive. Loop of perforated pipe beneath slab. When When existing soils are permeable. Interconnected strips of drainage mat beneath and around interior perimeter of slab. When When soil is well compacted. Option 1: Aggregate Option Caulk Slab Footing Aggregate Fill or native soils 6-mil sheeting 4-inches 4 inches of clean aggregate Between ¼ inch and 2-inch 2 in size Soil gas retarder Minimum 6 mil poly Overlapped and extended to edges Punctures and tears to be sealed Slab joints to be caulked and sealed. 3

4 Aggregate Option: Allowing for Lateral Air Flow Post and Beam Foundation with Grade Beam Riser Riser Sleeves Minimum of two grade beam penetrations. Minimum of 12 sq. inches of opening per 10 ft. of grade beam. Slab Slab Slab Slab Sch. 40 PVC Pipe PVC Pipe Coupling Tee Sch. 40 PVC Pipe PVC Pipe Coupling Sch. 40 PVC Pipe PVC Pipe Coupling Minimum Requirement Reduces Air Blockage Complies with code and reduces potential blockage Aggregate Option: Connecting Gravel to Vent Pipe Portion of vent pipe to be connected to sub- grade before concrete pour. Minimum 3-inch 3 Tee or equivalent Means to keep fitting from filling with gravel is preferred. Short length or perforated pipe beneath slab. Tee should be same size as riser Slab Alternates CVC CVC Alternate A No End caps Alternate B End caps 4

5 Option 2: Perforated Pipe Passive Vent Riser Perforated Pipe Continuous loop of perforated pipe. No No more than 12 inches from walls. Flexible Flexible or rigid pipe Wrapped Wrapped with filter cloth. Flexible and perforated pipe can be purchased with sock on. Trench Option CVC Instead of gavel throughout Gravel and perforated pipe in trench Loop design Sub-Grade Pipe Size and Loops Footprint (S.F.) Up to 2,000 2,000 to 4,000 4,000 to 6,000 8,000 Loops Diam. 3" 4" 3" 4" or Loops 2 Diam 3" 8000 Loops should be inter-connected 5

6 Perforated Pipe Option: Cross-Overs Riser Garage Grade Beam Pipe Loop Important: when passing under grade beams make sure that perforations of pipe allow drainage Make provisions for pipe to penetrate obstructions. Short Short lengths laid in trenches Tape ends to keep clear of debris-attach to main lop after grade beam finished Pipe Pipe sleeves in intermediate footings. Pass perforated pipe through. Perforated Pipe Option: Riser Sch. 40 PVC Pipe PVC Pipe Coupling Slab Corrugated, Perforated Polyethylene pipe 8 stub of 4 PVC Pipe Tee and perforated pipe same diameter as vent pipe. Option 3: Mat Option Exploded View of Mat Caulk Mat Filter Fabric Minimum 1 inch high & 12 inches wide. Lay mat directly on subgrade Pour concrete over mat 6

7 Option 3: Mat Option CVC Laid on subgrade, with vapor retarder between it and bottom of slab More expensive Offset by: Easier installation No No special aggregate Mat Option: Layout Riser Garage Grade Beam Mat 6000 Tee and mat to have same cross-sectional sectional free flow area as vent pipe. Installation of Mat Roll out Mat Make corners Place under re-bar Install Riser Photos: Compliments of professional Discount Supply Pour concrete on top of mat Finish Slab 7

8 Cross-Overs Plan for mat to cross through barriers Through Through intermediate foundation walls Under Under grade beams Insure Insure that concrete does not enter mat and that water can drain into sub-grade! Mat laid over footing prior to pouring of post-tension tension slab. Mat being routed under intermediate foundation wall and to another slab level Use of Water Drainage Systems as a Soil Gas Collection Methods If the sump collects water from the area inside the foundation walls, it could be considered a soil gas collection method, if an interior vent pipe is connected to it. Allowable: Aggregate completely under slab connected to sump Perforated water collection pipe connected to sump and inside of foundation wall It may be prudent to keep water drainage separate from radon system. Sump Pit Isolate sump from interior Reduces Reduces soil gas entry Trap Trap floor drains into sump Run Run condensate into trapped floor drain Seal Seal lid Gasketed cover Uniseals for penetrations CVC CVC 8

9 Stub Risers Up Before Floor-Pour Common to All Sub-Grade Systems Secure riser, so it is not tilted during concrete pour Temporarily cover end of riser to keep concrete and construction debris from entering and disabling system Short stub for vent. Secure in place. Tape over end to keep concrete out. Seal around joint after concrete cures. Connect to pipe when running vent. Label it! Sealing Concrete Slabs Reduces air flow to be handled by system Improves sub-slab slab depressurization Improves moisture reduction capabilities Reduces loss of interior conditioned air The thorough sealing of the concrete slab and walls is what in some areas has precluded the requirement of a fully sealed vapor barrier beneath the slab, which can be problematic and expensive. Sealing Slab Openings Improves Performance Sealing Slab Openings Cold Joint Expansion Joint Polyurethane caulk Cold joint feet per 11 oz. tube Expansion Joint 8 8 feet per tube Control joint 8 8 feet per 11 oz. tube Plumbing penetrations 9

10 Other Places to Seal Slab Plumbing penetrations Radon vent riser Use polyurethane caulk Polyurethane Type S Sonolastic NP-1 Large openings Plumbing block outs Liners Openings in slab for support posts Non-shrink grout Plumbing Block Outs Gaps Around Support Posts Condensate Drains and Sumps Condensate drains to be trapped Sumps to have sealed lids If If sump is floor drain, a lid with trapped inlet to be installed Foundation Walls All walls Damp-proofed proofed Solid walls Seal below grade penetrations Electrical, plumbing, etc Block walls Barrier to vertical flow at point above grade Continuous course of solid masonry, or One course of fully grouted block Solid beam above grade Brick veneer Course immediately beneath brick ledge to be sealed 10

11 Air Handling Units & Ductwork FAUs in crawl spaces to be sealed Reduces Reduces negative pressure that can be caused by air entering unit.. Below slab ductwork Large Large source of soil gas entry Seamless design Except if interior under positive pressure and operates continuously Ductwork in crawl spaces to be sealed. Crawl Spaces and Structural Floors Discharge Fan Plastic Caulked to Wall Depressurization Piping System Plastic Sheeting Spread on Dirt Crawl Space Perforated Pipe Below Plastic Sheeting CVC CERTI Treating Crawl Spaces Soil gas collected beneath plastic sheet Minimum 6-mil 6 polyethylene mil cross-linked is more durable App F says seams to be overlapped For best reduction and also moisture control, seams should be sealed and plastic sealed to walls. 11

12 Crawlspaces CVC Crawlspace Soil Gas Collector Hancor/ADS Single wall-annular pipe ASTM F Run length of crawlspace no less than 10 feet 4-inch Tee To Radon Vent System ADS Clay Snap Adapter AA Pound in, Drill 3 1½ sheet metal screws in Piping below plastic sheeting: Perforated ADS Piping above plastic sheeting: Non-Perforated, 4 inch Schedule 40 PVC DWV Crawlspace Riser Sealing plastic around riser is critical 1. Push roof Jack over elbow or tee 2. Make hole in plastic slightly smaller than Pipe diameter. 3. Caulk roof jack plate 4. Push poly down around pipe and onto caulk Polyurethane caulk Poly sheeting 12

13 Sealing Plastic Walls Bring Bring up wall 12 inches Options: Options: Continuous bead of caulk with edges taped until caulk cures Specialty tape or caulk against wall or caulk with furring strips ramset into walls Seams Overlap Overlap 12 inches and caulk Seams Prep Walls And Apply Caulk Brush debris off wall Apply polyurethane caulk 8 feet / 11 oz. tube Install Plastic Apply plastic Press into plastic Secure edges with duct tape until caulk cures 13

14 Fitting Around Plumbing Pipes and Pads Outline of Pipe Cut in Plastic Cut in Plastic Outline of Pad Caulk and Duct Tape Collar for Fitting Around Plumbing Collar for Fitting Around Concrete Pads Sealing Seams Overlap edges by 12 inches Caulk between overlaps Tape exposed edge Top sheet Bottom sheet Duct tape Continuous 1/2 inch bead of polyurethane caulk between overlapped sheets. Crawl Space Riser Seal plastic to riser Two Two sandwiched roof jacks Label riser 14

15 Multiple And Combination Foundations Separate foundation areas can be joined together. In In sub-grade In In house or attic Allows a single roof penetration Radon Vent Pipe System Connected after sub-grade system installed Pipe cannot be trapped Provide Provide space in chases Support at each floor level Discharge through roof behind ridge CVC Radon Vent Pipe Construction Schedule 40, PVC, DWV Optimal: 4 inch, Minimum: 3 inch Terminate where exhaust gases will not reenter house (like chimney) Do not use sheet metal or flex duct! 15

16 Route Pipe Through Warm Space Passive stacks work best when pipe run through warm space Furnace Furnace chases Do not connect to flue Plumbing chases Routing through cold spaces will reduce effectiveness GaragesGarages Outside Outside or outside walls Allow For Condensation In Vent Pipe Cold air temperatures on outer surface of pipe Condensate Air Flow Traps will fill with water Install pipe with positive drainage back to sub-grade No Traps! Power Supply to Fan Attic Allow For Potential Fan Installation Ceiling To Roof Penetration Fan 30 Plan for fan to be in attic or garage Cannot be inside living space or crawl space. Allow 30 inches of vertical run and 12-inches around future fan location Install duplex receptacle within 4 feet 16

17 Follow Plumbing Codes For Pipe Installation Follow local building codes, e.g. If If vent pipe is routed through garage a fire barrier will be needed Sill Plate Basement or Crawl Space Floor Foundation Fire-Resistive Wall To Fan Garage Floor Fire Barrier Assembly Rim Joist Supports, Etc. Nail plates at top and bottom of wall Foam around floor penetrations Strapping no less than 8 feet Slope back to suction point Avoid contacting rafters Discharge Back of ridge Roofer flashes around penetration Terminate 12 inches above roof Varmint guard on end 17

18 System Identification Label pipe at each level of building that it can be seen. Radon Reduction System. Label as system is installed to avoid mistaking this with plumbing system. System Label A system label should be located in a portion of the home advising occupant of the existence of a radon system. System Information System description Advice to test/re-test Maintenance/Troubleshooting Contact information Run system continuously if activated A System Performance Indicator Is Necessary If System Activated Note a special permit is required for installation of fan and indicator 18

19 Post Construction Testing and System Disclosure The proposed methods are prescriptive - not performance based. Testing is better performed after occupation. The need for further reductions is decision by occupant. Disclosure should be made to occupant (and future occupant) of systems existence and need to test to verify efficacy. Active System Operation and Maintenance Fan in attic Runs Runs continuously (60 watt) No No lubrication or maintenance required Life: Life: years Replacement cost: $150 Performance Indicator Shows Shows vacuum in system Not Not a radon monitor Duct tape large tears in crawlspace barrier Retest Monitor Confirms Vacuum Initial Initial long-term (provided) Retest Retest every two years (homeowner) ASTM 1465 Requires testing prior to occupation Active Active fan added if results > 4.0 or buyers expectation More details on: Active Active fan routing Soil Soil collector options LabelsLabels 38 Pages 19

20 Effectiveness & Costs of RRNC Passive RRNC systems typically reduce radon levels by about 50% on average, with variability in performance. EPA recommends RRNC for new homes built in high radon potential areas (Zone 1). The average cost for builders to include passive RRNC is approximately $390. The average cost to add a fan to a passive system is about $300. Source: Gene Fisher U.S. EPA Rate of Installation of RRNC in New Homes 160, , , ,000 80,000 60,000 40,000 20,000 0 Single-Family Detached Homes Built w/radon-reducing Features [U.S. Total of 1,570,900 Between ] Source: Phil Jalbert U.S. EPA One City s Experience Fort Collins, Colorado 20

21 So Does It Work? To answer this one must define success Risk Reduction? Features that reduce radon exposure by a Percentage OR? Reduction to a Recognized Level of Risk? Features that reduce radon to less than 4.0 pci/l Programmatic Approach Occupant expectation Early Efforts Compared Passive Systems To Other Homes In Same Neighborhood Simultaneous Short-Term tests on 89 Homes, 1991, Colorado Radon pci/l Unmitigated Passive Active Helpful, but assumption of similarity of homes in same neighborhood ood was problematic Estimating What Radon Levels Would Have Been If No Passive System Installed Capped System (unmitigated level) Uncapped Passive system operating Measure house with system capped (assumed unmitigated level) Measure house with passive system operative In some cases houses measured with system activated 21

22 6 COS Continuous Radon Measurements Uncapped/capped - October 2000 Radon (pci/l) Uncapped Passive System 4.0 Guideline MD6 48 MD5 54 NH2 MD4 MD3 MD1 ID1 NH5 60 CO5 CO1 IA1 NH4 MD7 ID3 IA4 MD2 ID4 66 ND2 IA2 72 MD8 NH1 CO3 78 ND1 84 ID2 90 IA3 NH3 ID8 ID6 CO2 ID7 ID5 Capped Passive System Clearly effect observed Fast response Hour Complications With Capped-Uncapped Studies Testing house at different periods Weather Weather can affect radon entry Short-term term rather than long-term tests Inconsistent methods used during construction Model Model standards not strictly adhered to NAHB-EPA Study 1994 Several States 40 ST Radon (pci/l Average Capped 5.9 pci/l Average Uncapped 2.5 pci/l % Reduction 57% MA1 MA3 MA4 NM6 MA2 NM1 4.0 Guideline NM2 NM3 NM8 NM5 NM10 NM7 NM9 NM4 Capped Uncapped 22

23 NAHB-EPA 1994 Study Where Systems Had Active Fans 25 Radon (pci/l) Guideline 0 NH2 MD1 ID1 NH5 CO5 MA4 NH4 ID3 ID4 IA2 NH1 CO3 IA3 Capped Uncapped Active Fan East Moline, Illinois Study Radon (pci/l) Average Capped 9.5 pci/l Average Uncapped 3.8 pci/l % Reduction 59% Guideline Capped Passive Dane County, WI ST Radon (pci/l) Average Capped 10.1 pci/l DW-6 DW-4 DW-3 DW-5 DW-7 DW-2 DW-1 Capped Uncapped Average Uncapped 3.8 pci/l % Reduction 62% 4.0 Guideline 23

24 Muscatine, Iowa ST Radon (pci/l) Average Capped 9.3 pci/l Average Uncapped 7.5 pci/l % Reduction 19% 4.0 Guideline 0 MI-12 MI-09 MI-06 MI-13 MI-10 MI-14 MI-08 MI-05 MI-04 MI-11 MI-01 MI-07 MI-02 Capped Uncapped Erie County, New York 2002 Vents routed through exterior walls ST Radon (pci/l) Average Capped 4.4 pci/l Capped Uncapped Average Uncapped 2.5 pci/l Without House 1, the reduction would have been 13% % Reduction 42% 4.0 Guideline Routing Pipe Up Exterior Wall Is Problematic Permeable System or Aggregate Passive Vent Stack Through Roof Stack effect greatly reduced. No room for future fan if activation is needed. 24

25 Colorado Front Range 1999 ST Radon (pci/l) CS2 CS3 CS5 C002 Average Capped C pci/l CS1 ALP1 Average Uncapped 2.3 pci/l ALP2 CS4 4.0 Guideline CS6 % Reduction 52% ASP1 Capped Uncapped Colorado 1999 Study Where Systems Had Active Fans Radon (pci/l) CS2 CS5 CS1 CS4 4.0 Guideline CS6 Capped Passive Active Fan Summary Of Cases Description Homes reviewed Number 117 Notes All but 5 in Zone 1 Mean Capped Measurements 6.8 pci/l Mean Passive 3.4 pci/l Average 51% Reduction Homes where capped results > 4.0 Number of homes where passive system reduced radon to < % of total 55% success for those > % Failure of passive systems where capped results were > % of those > 4.0 pci/l Homes where passive system was not necessary to reduce to less than % of total 25

26 Is Passive RRNC Working? 45% failure rate for homes that would have been above 4: Is Is this adequate for a Group A carcinogen? Could Could this be improved? Consistent adherence to standards Inspections Better assurance of testing after occupation 100% of homes activated reduced levels to less than 4.0 pci/l Do home buyers believe if a system is in place that it is working, i.e. below 4.0 pci/l? Which Criteria Defines Success? Overall risk: Overall Overall radon levels reduced by 51% Including reductions in homes that would have been < 4.0 without system There There are benefits assumed for any radon reduction Reduction to less than 4.0 pci/l: Success Success application rate of 28%* Of homes receiving RRNC, only 51% needed it Of the homes needing passive RRNC, only 55% were reduced to less than 4.0 pci/l. *51% x 55% = 28% success Yes Personal Conclusions Yes,, passive RRNC can work, if properly installed, and properly tested to determine need for activation. No No,, passive RRNC does not work programmatically, if it is assumed to function properly without validation by testing with an expectation of short-term term exposure being less than 4.0 pci/l. 26

27 Schools and Large Buildings Testing Schools and Large Buildings Similar to Homes Closed Closed building/short term Differences: All All occupied rooms on ground floor or directly above soil Test Test during occupied period Test Test when economizers are not operating HVAC has large impact HVAC System Concepts and Maintenance Mixing Chamber Blower Supply Fresh Outside Air Filter Heater Return

28 Fresh Air Make-Up Provided during occupied periods Typically designed for inches W.C. internal pressure (during occupied hours). Positive interior pressures thwarts entry of radon laden soil gas s (unless return ducts buried). Feedback control systems now in place Was not the case in 1989 Cycling causes significant variation in radon levels Integrating measurements (short or long) do not differentiate. Typical Hourly Variations in a School School Periods 12 Averages by Occupation Radon (pci/l) :12 17:12 19:12 21:12 23:12 1:12 3:12 5:12 7:12 9:12 11:12 13:12 15:12 17:12 19:12 21:12 23:12 1:12 3:12 5:12 7:12 9:12 11:12 13:12 15:12 17:12 19:12 21:12 23:12 1:12 3:12 5:12 7:12 9:12 11:12 Radon pci/l Total Unoccupied Occupied Effect of fresh air make-up. Integrating measurements may over estimate exposure Integrating Measurements Short-Term minimum 2 day Occupied and evenings Long-term Test minimum 90 days Includes weekends in addition to evenings Integrating measurements are biased to conditions existing when children are NOT in school and HVAC is adjusted for energy savings 2-day Short-Term test 3-Month long-term test (12 weeks) Integration Hours Occupied Hours Unoccupied Hours Percentage Unoccupied 58% 70% 28

29 How Variable Are Short-Term Room to Room Readings? T S T S Requires initial testing of all occupied rooms. Requires testing all rooms at the same time. Vapor Intrusion Radon isn t t the only soil gas that enters buildings VOCs In In soil In In groundwater Why does Vapor Intrusion occur? Lower pressure inside than outside drives vapor to enter buildings through cracks and openings in slab foundations or basement floors and walls. Similar Similar to how radon gas seeps into buildings. Diffusion Concentration gradients allow contaminate to migrate to where building vacuums can draw it in 29

30 Why is Vapor Intrusion a Concern? Common groundwater contaminants like TCE and PCE are volatile and may move readily through soil and into structures. Even in low concentrations, these vapors can be hazardous when inhaled. TCE TCE and PCE are probable carcinogens. Mitigation Methods Similar to radon. Minimize openings in foundation with sealing & caulking; seal ductwork. Use pressure to control intrusion Increase Increase outdoor air in HVAC create positive building pressure Active Active Sub-Slab Slab Depressurization (SSD) Low Low pressure differentials (0.002 water) are sufficient to reverse flow across a foundation. 30