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
TitleSpecification(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 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, 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

When ground moisture barrier is installed on sloping ground, or accessed for routine maintenance or storage it will be fastened to ground with durable fasteners or ballast(s)

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