2.0403.2 Closed Crawl Spaces—Ground Moisture Barriers

Topic:

Moisture

Subtopic:

Vapor Barriers

Desired Outcome:

Durable, effective air barrier Air barrier The separation between the interior and exterior environments of a building that slows air flow to the point that no smoke movement is visible at 50 pascals of pressure difference across the boundary and ground moisture barrier provide ongoing access and minimize ground vapor

For supporting material, see Calculation of the Infiltration Credit and Referenced Standards.

Single-Family Homes

Title	Specification(s)	Objective(s)
2.0403.2a Material Integrity	Care will be taken to prevent punctures during installation	Protect ground moisture barrier from damage during other crawl space work
2.0403.2b Coverage	An air barrier Air barrier The separation between the interior and exterior environments of a building that slows air flow to the point that no smoke movement is visible at 50 pascals of pressure difference across the boundary and ground moisture barrier, covering 100% of the exposed crawl space floor, will be installed and sealed to the wall's air and moisture barrier in accordance with ASTM ASTM ASTM International, www.astm.org E1643 and manufacturer's recommendations Ground moisture barrier will be fastened to ground in accordance with manufacturer's recommendations and extend a minimum of 6 inches up the foundation wall	Reduce ground moisture entering the crawl space Create a continuous and durable connection between the wall and ground air and moisture barriers
2.0403.2c Material specification	A ground moisture barrier with a rating of no more than 0.1 perm will be used A ground moisture barrier will be used that meets tear and puncture resistance standard ASTM ASTM ASTM International, www.astm.org E1745 Homeowner will be advised that all plastic is biodegradable and will have a life span much shorter than the home (5 years), and it will need replacing to remain effective	Reduce ground vapor entering the crawl space Ensure crawl space is accessible for service and maintenance without destroying the integrity of the moisture barrier
2.0403.2d Overlap seams	When seams exist, they will be overlapped a minimum of 12" with reverse or upslope lapping technique Reverse or upslope lapping technique Upper course laps under a lower course to keep the moisture under the barrier For wall to floor connection, the wall moisture barrier will be installed under the ground moisture barrier	Keep water under the liner
2.0403.2e Fastening See redline change(s)	The air barrier Air barrier The separation between the interior and exterior environments of a building that slows air flow to the point that no smoke movement is visible at 50 pascals of pressure difference across the boundary and ground moisture barrier will be fastened to the ground to prevent movement in accordance with ASTM ASTM ASTM International, www.astm.org E1643 and manufacturer's recommendations	Prevent movement and uplift of the air barrier Air barrier The separation between the interior and exterior environments of a building that slows air flow to the point that no smoke movement is visible at 50 pascals of pressure difference across the boundary and ground moisture barrier
2.0403.2f Sealing seams	A durable sealant compatible with the air barrier Air barrier The separation between the interior and exterior environments of a building that slows air flow to the point that no smoke movement is visible at 50 pascals of pressure difference across the boundary and ground moisture barrier will be used	Maintain continuous air barrier Air barrier The separation between the interior and exterior environments of a building that slows air flow to the point that no smoke movement is visible at 50 pascals of pressure difference across the boundary and ground moisture barrier
2.0403.2g Air barrier Air barrier The separation between the interior and exterior environments of a building that slows air flow to the point that no smoke movement is visible at 50 pascals of pressure difference across the boundary , ground moisture barrier penetrations, including fastener penetrations	A durable sealant, compatible with the air barrier Air barrier The separation between the interior and exterior environments of a building that slows air flow to the point that no smoke movement is visible at 50 pascals of pressure difference across the boundary and ground moisture barrier, will be used Physical attachments will be provided where practical (e.g., masonry columns, footings)	Maintain continuous air barrier Air barrier The separation between the interior and exterior environments of a building that slows air flow to the point that no smoke movement is visible at 50 pascals of pressure difference across the boundary and ground moisture barrier
2.0403.2h Drainage	The air barrier Air barrier The separation between the interior and exterior environments of a building that slows air flow to the point that no smoke movement is visible at 50 pascals of pressure difference across the boundary and ground moisture barrier will not interfere with the established drainage pattern	Ensure proper drainage
2.0403.2i Drainage points	Interior drainage collection points will be accessible from above and below the air barrier Air barrier The separation between the interior and exterior environments of a building that slows air flow to the point that no smoke movement is visible at 50 pascals of pressure difference across the boundary and ground moisture barrier	Remove water above and below the air barrier Air barrier The separation between the interior and exterior environments of a building that slows air flow to the point that no smoke movement is visible at 50 pascals of pressure difference across the boundary and ground moisture barrier