addressing radon in the home · radon in water • radon gas is less soluble in hot water than in...

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3/2/2020 1 Addressing Radon in the Home Dick Kornbluth [email protected] (315)391‐6886 Better Buildings: Better Business Wisconsin Conference March 9-10, 2020 What This Session Covers Part 1:Intoduction to radon What it is Where its found How it’s measured The health risks of exposure to radon Part 2:Mechanisms of radon entry Part 3: A survey of radon entry routes Part 4: Sealing procedures Part 1 About Radon 1 2 3

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Page 1: Addressing Radon in the Home · Radon in Water • Radon gas is less soluble in hot water than in cold water • Known health risk from water‐borne radon is due to radon released

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Addressing Radon in the Home

Dick Kornbluth

[email protected]

(315)391‐6886

Better Buildings: Better BusinessWisconsin Conference

March 9-10, 2020

What This Session Covers

• Part 1:Intoduction to radon– What it is

– Where its found

– How it’s measured

– The health risks of exposure to radon

• Part 2:Mechanisms of radon entry

• Part 3: A survey of radon entry routes

• Part 4: Sealing procedures

Part 1About Radon

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What is Radon?

•Gas

•Colorless

•Odorless

•Tasteless

•Chemically inert

•Radioactive

• Radioactive half-life = 3.8 days

Where it Comes From 

• Generated by the natural, spontaneous radioactive decay of Uranium

• Found where there are deposits of uranium in specific rock formations:– Mostly shales, limestones and granites

Radon Measurement Units

• In the United States, radon levels are measured in pico curies per liter (pCi/l) which is a measurement of radiation

• According to the EPA, the average outdoor level of radon is 0.4 pCi/l

• Average indoor level is 1.3 pCi/l

• Radon should be mitigated if average indoor level is 4 pCi/l or greater

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EPA Radon Map

Zone 1 = >4 pCi/l

Zone 2 = 2-4 pCi/l

Zone 3 = < 2 pCi/l

What Does Radon Do?

Long time exposure to radon is considered to be the second leading environmental cause of lung cancer after cigarette smoking

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Health Risks from Radon Exposure

Source: EPA’s  A Citizen’s Guide to Radon

Radioactive Half‐Life

• Time it takes for one‐half of a given amount of a radioactive element to transform into another radioactive element

– For Uranium = 4.5 billion years

– For Radon      =3.8 days

Uranium 2lb

Radon 1 lb

4.5 billion yrs

Uranium 1lb

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Radon Measurement Units

• Radon – pCi/l

• Pico curies/liter of air in US

• Progeny – WL – Working Level

• Working level – For residential applications = pCi/l x .5

• Used for measuring worker exposure in certain industries 

Testing Radon 

• Testing for Radon in Air• Short‐Term Tests – 2‐90 days ‐ Integrated

• Charcoal test kit – most common– Provides single overall average radon level over test period

– Must be sent to lab for analysis

– Cost: $15‐$30/kit

• Liquid Scintillation

• Electronic Monitors – Provides hourly radon levels and/or average radon level over test period

• E‐perm– Electret Ion Chamber

• Long‐term Tests – 90 days to 1 year• Alpha track – most common

• Electronic Monitors 

• E‐perm

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– Long‐term Tests – 30 days to 1 year

• Alpha‐Track– Provides single overall average radon level over test period

– Must be sent to lab for analysis

• Testing for Radon in Water

– Only applies to well water

Type of Test Short‐term Long‐term DIY

Charcoal  2‐7 Days Yes

Liquid scintillation 2‐7 days Yes

E‐Perm – electret ion chamber

2‐90 days 91‐360 days No

Continuous radon monitor (CRM)

2‐90 days 91‐360 days Yes/No

Alpha‐track    30‐90 days 91‐360 days Yes

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Short‐Term Radon Testing Devices

Charcoal Test Kit

Charcoal Test KitEperm Test

Continuous Radon Monitor

Liquid Scintillation

Alpha-track

DIY Continuous Radon MonitorsDon’t do hourly readings

Airthings CorentiumHome $179-$199

Safety Siren Pro $149.99

Radon in Water

• Radon gas is less soluble in hot water than in cold water

• Known health risk from water‐borne radon is due to radon released into air and breathed in as a result of:

– Cooking

– Showering

– Clothes and dish washing

• Approx 10,000 pCi/l in water = 1 pCi/l in air

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• EPA has proposed to require community water suppliers to provide water with radon levels no higher than 4,000 pCi/L, which contributes about 0.4 pCi/L of radon to the air in your home.

• Easily tested

Short‐Term Tests

• EPA Protocols– Real Estate Transaction related

• Test in lowest level of house suitable for living space– E.g. Modern house with unfinished basement which could be converted to living space

– Don’t test in crawlspaces

– Don’t test in basements not suitable for living space

» E.g. 19th century house with dirt floor basement with less than 6’ in head room

– Not real estate transaction related• Test in lowest level of house used for living space

Short‐Term Test ProtocolFor CC, LS and CRM for 2‐7 dys

• House must be in “winter” condition

– All windows closed at least 12 hrs before test starts

– All windows closed during test

– All exterior doors closed except for normal going out and coming in for 12 hrs before test and during test 

• Test must be kept away from sources of heat, moisture and moving air during test

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Can’t measure radon with a single point reading

• Radon levels fluctuate constantly in any building

• All the factors that can change the pressure in a house will affect interior radon levels:– Exhaust fan operation

– Wind

– HVAC operation

– Barometric pressure changes

– Rain 

– Outside temperature changes

– Stack effect

Actual Continuous Radon Monitor Traces

Avg23.1pCi/l

3.1 pCi/l

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Alpha Track Test

Alpha‐Track• Can do short‐term (30‐90 dys) or long‐term (90 dys‐1 yr) 

• No special living condition requirements– Windows don’t have to be kept closed (Test period is 1 mo to 1 yr!)

– Test not affected by moisture or humidity

• Detector must be sent away to manufacturer for analysis

• Results reported as average radon level over test period

Part 1 Summary

• Radon: colorless, odorless, tasteless, chemically inert, radioactive gas

• Generated by spontaneous decay of Uranium

• Found in deposits of shale, limestone and granite

• Uranium half‐life = 4 billion yrs

• Radon half‐life = 3.8 days

• Second leading cause of lung cancer after cigarette smoking

• Radon is easily measured in buildings with either short‐term or long‐term tests

– Short‐term tests = 2‐30 days

– Long‐term tests = 31 days – 1 year

• Need closed house conditions for short‐term tests, unless doing 30‐day test

• Karst geology makes reliable testing difficult

• According to the EPA, Radon action level is 4 pCi/l

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Part 2Mechanisms of Radon Transport 

Into Buildings

What Determines Radon Level in Building?

Uranium

Source Strength

Soil Porosity

Radon Soil Concentrations and Transport Mechanisms

• Radon level in a house is influenced by two factors in the soil:

– Its source concentration – Uranium

–How easily it moves through the soil• Soil particle size: gravel loam sand clay

• Soil moisture content: dry wet

• Dry, gravelly soil Radon moves more quickly

• Wet, clay soil Radon moves more slowly

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Radon Transport into Buildings

Radon levels in a building fluctuate continually. There are many factors influencing rate of radon transport into building:

General Mechanisms of Radon Transport

• Diffusion

• Pressure driven flow

• Radon in water

Diffusion

• Relatively slow process

– Not major mechanism for radon entry

– Concrete is porous, so diffusion accounts for some radon entry

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Radon Entry is a Pressure‐Driven Flow

Environmental Factors

• Barometric pressure

• Rain

• Wind

Barometric Pressure Effects

• Small

• Radon levels in soil increase as barometric pressure decreases

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Rain Effects

• Temporary

• Rain spike – as soil becomes saturated radon levels in building increase

Wind Effect

Building System Factors

• Stack Effect

• Mechanical ventilation

• Duct leakage

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Stack Effect

Stack Effect

• Can be complex interaction

• Air sealing reduces exfiltration at top and infiltration at bottom

– Less radon coming in

• But air sealing reduces natural ventilation, building tighter

– Radon levels can increase

Mitigating RadonSub‐Slab Depressurization

In-Line Fan

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Non‐Heating Season Stack Effect 

Effect of opening up second floor window at 9:30pm

Window opening effect – Stack

Effects of Mechanical Ventilation

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RETURN LEAK EFFECTS

SUPPLYRETURN

Basement

1ST Floor

Chimney

Radon and House TightnessNo correlation established between indoor radon levels and building tightness

Data from studies in the 1990’s showed a scatter plot when radon levels were plotted against building air leakage measurements

But that’s a different question than the one that asks “What happens to radon levels when we increase building tightness?”

Oak Ridge IAQ Study2010‐2011

• Effect of weatherization on radon levels inconclusive:

– Some houses, radon increases

– Some houses, radon decreases

– Some houses, radon stays the same

• Can be issue with measuring techniques and weather‐related effects

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Radon in Water

Radon in Water

• Source: Wells, can be individual or community

• Health risk is not from drinking; it’s from breathing radon released into the air when water is heated:  showering, cooking, washing

Radon in Water

• Water/Air equivalent: 

– 10,000 pCi/l in water = 1 pCi/l in air

• Testing for radon in water

– Test kits are available 

• Radon in water problems can be fixed with plumbing aeration systems that release radon before it gets into house

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Part 2 Summary

• Soil factors that influence rate of radon entry into buildings

– Concentration of uranium in ground

– Porosity and wetness of soil

• Dry, gravelly soil – radon moves more easily

• Wet, clay soil – radon moves more slowly

• Diffusion vs pressure‐driven flow

• Environmental factors

– Barometric pressure

– Rain

– Wind

• Building system factors

– Stack effect

– Mechanical effect

– Duct leakage

• Radon in water

Part 3: Radon Entry Points

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Radon Entry Points

Locations of Radon Entry in Slab

Radon

Floor cracksPerimeter drain

Sump

Floor/wall joint

Floor penetrations

Wall penetrations

Block wall core

Floor drain

Crawlspaces

Crawlspace

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Block Wall Core

Radon

Block wall core

Rubble Stone Walls

• Can be source of radon

• Difficult to determine if wall is source

• Can do short term radon test called Flux Test

– 2‐day exposure sufficient

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Charcoal test kit

Radon Flux Test

Floor Cracks

Radon

Floor cracks

Floor Cracks

Cracks come in different sizes!

Large

Medium

Hairline

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Expansion joints

Can floor crack sealing eliminate radon entry?

Diameter of Radon atom = .000000008 inches

Diameter of human hair  = .0030 inches

Diameter of hairline crack = .003 inches

Hairline crack  = 375,000 x diameter of Radon atom

No, but you can reduce rate of radon entry into the living space

Floor and Wall Penetrations

Radon

Floor penetrations

Wall penetrations

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Floor and Wall Penetrations

Floor Drains

Radon

Floor drain

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Floor Drains• Floor drains are a sub‐set of floor penetrations.

• They can be connected to the ground (A) or connected to the waste system (B)

A B

Radon entry for sure

No radon entry if no leaks in pipe

Floor Drains

Condensate Drains

• For condensate lines from furnaces and central air conditioners

• Can empty into floor drains and sumps, but sometimes just a hole in the floor.

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French (perimeter) Drains

Radon

Perimeter drain

French (perimeter) Drains

• Most commonly installed as part of a water management system

• Frequently associated with a sub‐slab drain tile system and sump pump

• Occasionally connected to a drain to daylight, with no sump

Drain tile

Open French (perimeter) Drain

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Drain to Daylight

French Drain with Weep Holes in Block

Weep hole

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French Drain Covered by Framing

French Drain Behind  Framing

Floor/Wall Joint

Radon

Floor/wall joint

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Floor/Wall Joint

• Can be as narrow as a floor crack and as wide as a French (perimeter) drain

– Some builders have installed the slab as a “floating slab” not anchored to the foundation walls

– If there is a water management system there will be either a sump or a gravity drain to daylight. There may even be a sump with no pump and with a drain to daylight.

Sumps

• Can be part of a water management system

• Consists  of  a:

– sump pit

– sump basin or liner

– sump pump to remove water

– check  or backflow prevention valve to prevent water from coming back into the sump basin

– discharge line to deliver the water to the exterior of the building

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https://home.howstuffworks.com/home-improvement/plumbing/sump-pump1.htm

Sump Pumps

• Two Types:

– Submersible – totally contained in the basin

– Pedestal – pump motor housed in a shaft that extends above the basin

Submersible pump Pedestal pump

How the Sump Pump Works

• All sump pumps have a float switch

• As the water in the basin rises to a certain level, the float rises and triggers the pump to remove the water

Float and rod move

Untethered Float Vertical Float –rides on rigid rod

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Sump Basins

• Most commonly plastic prefabricated

But Sump Pits Can be Any Hole

Are All Sump Pits Connected to the Ground?

No, if used for gray water from washing machines

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If a sump pit is connected to the ground, it must be sealed!

Crawlspaces

Crawlspace

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Crawlspaces

• Major entry point for radon

• Can be accessible or inaccessible

• Can be used for storage and/or required for access or not – sealing strategy will differ

Other Holes

Part 3 Summary

Radon entry points

• Block walls – not always

• Rubble stone walls – not always

• Floor cracks

• Floor/Wall penetrations

• Floor drains

• Condensate drains

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• French (perimeter) drains

• Floor/wall joint

• Sumps

• Crawlspaces

• Other holes

Part 4 – Sealing Procedures

Goals

• All accessible soil gas entry points are sealed using appropriate sealing materials and methods

• There is no entry of soil gases into basement or living space (slab on grade) from the holes that are sealed 

• Work is done in compliance with nationally recognized radon mitigation industry standards

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National Radon Mitigation Standards

There are two standards which govern the radon mitigation industry:

An ASTM standard:

And an American Association of Radon Scientists and Technologists standard:

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Radon Reduction Procedures

• Procedures divided into 2 groups

– Basic procedures

• Should be done on every house

• Reasonable cost to do in terms of labor and materials

– Advanced procedures – Shown in red

• Should be done if time and budget permits

• I will cover basic procedures first, then talk about Advanced Procedures

Basic Procedures

• Block wall core sealing

• Rubble stone wall sealing

• Floor crack sealing

• Drain sealing

– Floor drains

– Condensate drains

• Wall penetration sealing

• Floor penetration sealing 

• Floor/wall joints

– Accessible floor/wall joints

– Floor/wall joints behind finished walls

• Framing over joint

• Joint behind framing

• French drains

– Accessible French drains

– French drains with weep holes

– French drain behind finished walls

• Framing over drain

• Drain behind framing

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• Other holes

– Holes in concrete slab

– Holes under bathtubs 

– Holes under furnaces

Basic Procedures

Block wall cores

• Can use communication test to check for block wall connection to ground

• Connection to soil usually not an issue for exterior block walls due to waterproofing

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May be an issue for interior block walls 

Living spaceGarageCrawlspace

Internal kneewall –no waterproofing

Waterproofing

Sealing block wall cores

Stuff w fiberglass and fill with mortar

Fill w spray polyurethane foam

QA: No smoke enters block wall core when shop vac is on

Spray foam

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Fiberglass

Mortar

Rigid foam boardCaulk

Rubble Stone Walls

• Sealing is problematic

• Research indicates that rubble walls need to allow moisture migration through wall to maintain structural integrity if lime‐based mortar used

• If sealing, necessary to maintain drainage plane

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Membrane

Floor drainage

Sealing Rubble Stone Walls

Floor Cracks

• For cracks less than ½” width, seal with urethane gunnable caulk

• For cracks ½” wide or greater, insert backer rod in crack and then seal with gunnable or self‐leveling urethane caulk– Polyethylene Backer rod  

• Include expansion joints

Recommended Types of Urethane caulk Type NP‐1 = Gunnable non‐saggingType SL ‐1 =  Self‐leveling (best for wide cracks) 

Floor Crack Sealing

Floor Crack

Expansion Joint

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Floor/Wall Penetrations

• For joints less than ½”, seal with NP‐1 caulk

• For joints between ½” and 1”, plug with backer rod and then seal with NP‐1 caulk

• For joints greater than 1”, seal with spray foam insulation

• QA: No smoke enters joint when shop vac is on

Floor Drains

• Floor Drains

• Condensate drains

• QA: When drain top is temporarily sealed with duct tape, no smoke enters joint with floor when shop vac is on

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Retrofit One Way Drains

Dranjer FR-2

Good for drains 2” to 8” diameter

From instruction sheet

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Condensate Drains

• If condensate drain is a floor drain, replace with a one‐way drain, which allows water to enter but prevents soil gases from coming into basement or living space (for slab on grade houses)

One-way Drain

• If condensate line is inserted into a hole in the slab, seal the line in the hole with caulk.

• Use silicone caulk which will allow line to be removed from drain 

QA: For regular drains, see floor drain aboveFor drilled hole in floor, no smoke enters drain 

when shop vac is on

Make sure there is a trap in the condensate line to prevent soil gases from entering the room.

The trap should have at least 3” of water on each side

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French (perimeter) Drains

• Necessary to seal drains without interfering with their water processing function

Drain tile

French Drain Procedure

• Cut backer rod to fit tightly into top half of French drain channel leaving at least 1/2 “ of space between top of backer rod and floor

• If filling with mortar, fill remaining channel with mortar

• If filling with SL‐1 self‐leveling caulk, make sure that there are no gaps between the backer rod and the sides of the channel

• If there are, fill them with NP‐1 caulk first

Backer rod installed

Backer rod

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French drain sealed

French Drain with Weep Holes or Drainage Channels 

• When sealing French drain, need to incorporate weep holes or drainage channels into seal

• One option is to use a heavy duty membrane to cover both the drain and the weep hole

– Polyethylene sheeting, 10  mil thick or greater

– 45 mil EPDM roofing

• Secure to wall and to floor with NP‐1 caulk and reinforce with pressure‐treated 1”x2” secured with mechanical fasteners.

• If there is evidence of water entry through the wall, extend membrane above the water entry point

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Floor/Wall Joint

Floor/Wall joint

Floor/Wall Joint

• For joints less than ½”, seal with NP‐1 caulk

• For joints between ½” and 1”, plug with backer rod and then seal with NP‐1 caulk

• For joints greater than 1” plug with backer rod and fill with mortar or SL‐1 caulk

• QA: No smoke enters joint when shop vac is on

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Floor/Wall Joint

Narrow joint Wide joint

Backer rod

Sump Sealing

• First determine if sump pit is connected to the ground; yes, if

– the bottom of the pit is open to the ground and not concrete

– There are  drain tile openings in the basin

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Concrete sump w concrete floor

Concrete sump w dirt floor

Sump pit with drain tile Sump pit with drain tile

Sump Cover Installation

• Submersible pumps

– Cover can be fabricated or purchased commercially

– Cover must be material that is rigid and water resistant

• 1/4 polycarbonate sheet – Lexan, e.g.

• 1/2” or greater pressure‐treated plywood

• Cover should be cut to fit inside top of basin

• Install a one‐way drain in the cover

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Sump Sealing

• Cut holes for any piping that must penetrate the cover

• Put a notch in one of the holes for the power cord

• Disconnect the piping from the sump

• Run a bead of silicone caulk around the edge of the sump basin

• Install the sump cover

Sealed Submersible Pumps

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Sealed Submersible Pumps

Pedestal Pumps

• Cannot use flat cover because motor for pump sits on rigid stalk and cannot be disassembled.

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Two Options

• Replace pedestal pump with submersible pump

– Install sump pump with equal or greater horse power to the pedestal pump.

• Install a commercially obtainable HiRise cover

HiRise Cover

Special case: Backup Systems

• Some sumps have electrical or water‐drivennsump backup systems. 

• Difficult to install flat  cover

• Can use HiRise cover

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Crawlspace sealingNational Radon Mitigation Standards

• Membrane for sealing crawlspaces must be a minimum of 3‐mil cross‐laminated polyethylene sheeting or 6‐mil polyethylene sheeting

• Heavier gauge sheeting (10‐mil or thicker) must be used if crawlspace is used for storage or accessed for 

maintenance

• The membrane must be sealed around all posts

– Conflicts with NREL SWS’s which do not allow wood posts below membrane

• Membrane must be sealed to foundation walls with NP‐1 caulk as long as walls are flat

– Can use spray polyurethane foam for irregular surfaces such as rubble stone walls

• All penetrations through the membrane must be sealed

• All joints in the membrane must be lapped at least 12”

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• If heavier membrane is used, reinforce attachment to foundation wall and posts with 1”x2” pressure‐treated furring strips, caulked in place.

• Install floor drain in lowest part of crawlspace

• Install sump pit and sump pump if water entry is an issue

– Note: If evidence on foundation walls of water entry, secure membrane to foundation walls above this point.

Install one way drain in crawlspace membrane

PT PlywoodMembrane

For standard membranes For heavier membranes

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Rubble Stone Walls

Before

After

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Other Holes

• Any hole through the slab should be sealed with appropriate material, e.g. concrete.

Fill with concrete Cover with Lexan

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