Polyethylene Lapped Up Walls/Piers and Secured in the Ground

Please Register or Login to Provide Feedback.

Building Science-to-Sales Translator

Foundation Capillary Break over Aggregate =
Foundation Floor Water Barrier

Technical Description: 

Without a capillary break, moisture can wick-up through the pores of a concrete slab and enter the crawlspace, which can lead to mold and the moisture-related failure of building materials. Also, the air exchanged between the moisture-laden crawlspace and the house can carry mold and contaminants into the home. An essential part of a comprehensive approach to creating a water-managed home and foundation is to provide a capillary break (i.e., a water-impermeable material) under the slab or at the crawlspace floor. If the house has a crawlspace, the entire floor should be covered with 6-mil plastic sheeting that is overlapped 6-12 inches and taped at the seams and caulked and fastened to the walls with furring strips that are nailed or screwed into the concrete. If there are piers in the basement, the sheeting is lapped up the sides of the piers and taped.

Related Terms

Dry-by-Design Foundation Floor
Foundation Floor Water Barrier Technology
Professionally Installed Slab Water Protection
Slab Water Barrier
Foundation Floor Water Barrier
Sales Message
Foundation floor water barriers help drain water away from under the slab. What this means to you is peace-of-mind knowing your home has a comprehensive set of measures that minimize the risk of water damage in your basement. Wouldn’t you agree every home should have full water protection?

Climate

Polyethylene sheeting is not required in Dry (B) climates as defined by the 2009 IECC, except in U.S. EPA Zone 1 Radon areas.  Polyethylene sheeting is also not required for raised pier foundations with no walls. Click here for the 2009 IECC Interactive Climate Zone Map.

Energy Star Version 3, (Rev 07)

Water Management Checklist, Water-Managed Site and Foundation. Capillary break at all crawlspace floors using >= 6 mil polyethylene sheeting, lapped 6-12 in., and installed using one of the following three options: placed beneath a concrete slab; OR lapped up each wall or pier and fastened with furring strips or equivalent, OR, secured in the ground at the perimeter using stakes. Polyethylene sheeting is not required in Dry (B) climates as shown in 2009 IECC Figure 301.1 and Table 301.1.

climate zone map

International Energy Conservation Code (IECC) Climate Regions

Description

Moisture in crawlspaces can cause harm to the home by promoting mold and rot along floor joists and rim joists. Some moisture in crawlspaces occurs from water vapor in soil. To prevent water vapor in the soil from entering the crawlspace, the crawlspace floor should be covered with a heavy plastic that is sealed to the walls. This plastic ground cover should be installed regardless of whether the crawlspace is vented or unvented. This plastic covering will also help keep soil gases from entering the home. This task should be included in the contract for the appropriate trade depending on the workflow at the specific job site.

Other Considerations: Moisture can enter a crawlspace from sources other than vapor from the ground. In vented crawlspaces, the dominant source of crawlspace moisture is bulk water intrusion from improper grading of the site, lack of perimeter drainage, improper irrigation practices, etc.; see Final Grade. In humid climates, water vapor in warm outdoor air can enter through crawlspace vents and condense on cooler framing. In humid climates, building scientists recommend building insulated, unvented crawlspaces (see Basement Walls). Because radon accumulation in a home cannot be measured until after the home is built, as an added precaution consider installing a passive radon venting system, which collects soil gasses under the plastic and vents them through the roof via a vent pipe (see Radon Resistant Construction).

How to Install a Polyethylene Ground Cover

  1. Spread one layer of 6-mil or thicker polyethylene across the entire ground surface. Edges should lap up side walls at least 8 inches.
  2. Overlap all seams by 12 inches and tape them. Ensure that surfaces where tape will be applied are clean and dry.
  3. Attach the polyethylene to the walls at least 6 inches up the walls or to a height at least equal to ground level. Attach the polyethylene with pressure-treated wood furring strips or other mechanical fasteners. The edges can be sealed to the wall with fiberglass mesh tape and duct mastic. 

A continuous layer of polyethylene covers the crawlspace floor and is attached to the wall with wood nailing strip

Figure 1 - A continuous layer of polyethylene covers the crawlspace floor and is attached to the wall with wood nailing strips  Reference

 

  4.  Lap the vapor retarder up the sides of any interior columns at least 4 inches above the crawl space floor.

  5.  For added durability, consider one of the following:

 a. Lay one polyethylene groundcover at the beginning of construction; when construction is completed, install a second sheet over the first sheet  to cover any rips in the first sheet (make sure the first sheet is dry and free of organic matter). Seal the top sheet to the walls. 

 b. Lay a vinyl runner or extra plastic over any areas that will get traffic, such as a service path to the furnace.

 c. Cover the single, sealed layer of polyethylene with a concrete slab 2 or more inches thick.

Polyethylene completely covers the floor of this crawlspace and is attached to the walls and piers as well 

Figure 2 - Polyethylene completely covers the floor of this crawlspace and is attached to the walls and piers as well  Reference

Polyethylene is being attached to the crawlspace floor and walls with plywood furring strips

Figure 3 - Polyethylene is being attached to the crawlspace floor and walls with plywood furring strips  Reference

Ensuring Success

Visually inspect the crawlspace to ensure that all earthen floor is completely covered with a layer of polyethylene sheeting at least 6 millimeters thick, that the sheeting extends up the sides of each wall or pier and is mechanically fastened with wood furring strips or other fasteners, and that any seams in the plastic are overlapped 6 to 12 inches and taped.

Please Register or Login to Provide Feedback.

Scope

Capillary break at all crawlspace floors using ≥ 6 mil polyethylene sheeting, lapped 6-12 in., and lapped up each wall or pier and fastened with furring strips or equivalent

Water Managed Site and Foundation

Capillary break at all crawlspace floors using >= 6-mil polyethylene sheeting, lapped 6-12 inches, and lapped up each wall or pier and fastened with furring strips or equivalent.

  1. Install furring strips or equivalent to all crawlspace walls and piers.
  2. Cover entire area with at least a 6-mil polyethylene sheeting and overlap the sheeting at least 6-12 inches.
  3. Attach sheeting to furring strips, or equivalent, installed on all crawlspace walls and piers.

Capillary break at all crawlspace floors using > 6-mil polyethylene sheeting, lapped 6-12 inches, and secured in the ground at the perimeter using stakes.

  1. Secure the sheeting in place by staking at the perimeter.

ENERGY STAR Notes:

Only one item of detail 1.4 on the Water Management Checklist must be met to comply with ENERGY STAR.

Not required in Dry (B) climates as shown in 2009 IECC Figure 301.1 and Table 301.1.

Not required for raised pier foundations with no walls. To earn the ENERGY STAR, EPA recommends, but does not require, that radon-resistant features be included in homes built in EPA Radon Zones 1, 2 & 3. For more information, see Indoor airPlus.

ENERGY STAR Notes for Existing Homes:

For an existing slab (e.g., in a home undergoing a gut rehabilitation), in lieu of a capillary break beneath the slab, a continuous and sealed Class I or Class II Vapor Retarder (per Footnote 8) is permitted to be installed on top of the entire slab. In such cases, up to 10% of the slab surface is permitted to be exempted from this requirement (e.g., for sill plates). In addition, for existing slabs in occupiable space, the Vapor Retarder shall be, or shall be protected by, a durable floor surface. If Class I Vapor Retarders are installed, they shall not be installed on the interior side of air permeable insulation or materials prone to moisture damage.

Training

Right and Wrong Images

Presentations

None Available

Videos

  1. Polyethylene Lapped Up Walls/Piers and Secured in the Ground
    Courtesy Of: Crawlspace Repair

    Video describing how to properly install foundation seal tape. 

CAD Images

None Available

Compliance

ENERGY STAR Version 3, (Rev. 07)

Water Management Checklist, Water-Managed Site and Foundation. Capillary break at all crawlspace floors using ? 6 mil polyethylene sheeting, lapped 6-12 in., and installed using one of the following three options: placed beneath a concrete slab; OR lapped up each wall or pier and fastened with furring strips or equivalent, OR, secured in the ground at the perimeter using stakes. Polyethylene sheeting is not required in Dry (B) climates as shown in 2009 IECC Figure 301.1 and Table 301.1. Polyethylene sheeting is also not required for raised pier foundations with no walls. To earn the ENERGY STAR, EPA  recommends, but does not require, that radon-resistant features be included in homes built in EPA Radon Zones 1, 2 and 3.

For an existing slab (e.g., in a home undergoing a gut rehabilitation), in lieu of a capillary break beneath the slab, a continuous and sealed Class I or Class II Vapor Retarder (per Footnote 8) is permitted to be installed on top of the entire slab. In such cases, up to 10% of the slab surface is permitted to be exempted from this requirement (e.g., for sill plates). In addition, for existing slabs in occupiable space, the Vapor Retarder shall be, or shall be protected by, a durable floor surface. If Class I Vapor Retarders are installed, they shall not be installed on the interior side of air permeable insulation or materials prone to moisture damage.

DOE Zero Energy Ready Home

Exhibit 1: Mandatory Requirements. Certified under ENERGY STAR Qualified Homes Version 3.

More Info.

Case Studies

  1. Author(s): PNNL
    Organization(s): PNNL
    Publication Date: April, 2012

    Case study about a home builder that has refined its home designs to achieve HERS scores of 49 to 56 on 40 to 70 homes per year.

References and Resources*

  1. Author(s): Dastur, Davis, Warren
    Organization(s): Advanced Energy
    Publication Date: February, 2012

    Guide about designing and installing closed crawlspaces.

  2. Author(s): DOE
    Organization(s): DOE
    Publication Date: April, 2014

    Standard requirements for DOE's Zero Energy Ready Home national program certification.

  3. Author(s): EPA
    Organization(s): EPA
    Publication Date: June, 2013

    Standard document containing the rater checklists and national program requirements for ENERGY STAR Certified Homes, Version 3 (Rev. 7).

  4. Author(s): EPA
    Organization(s): EPA
    Publication Date: February, 2011

    Guide describing details that serve as a visual reference for each of the line items in the Water Management System Builder Checklist.

Last Updated: 08/15/2013

Mobile Field Kit

The Building America Field Kit allows you to save items to your profile for review or use on-site.