Insulating Your Crawlspace Walls

An under-insulated crawlspace can be a significant source of home energy loss. The best crawl space insulation for your home depends on if your crawlspace is conditioned (heated or cooled by a furnace or air conditioner) or unconditioned.

In a vented or unconditioned crawlspace, only the floor is insulated. In a heated crawl with uninsulated pipes or ducts, the walls need to be insulated and a polyethylene vapor retarder installed across the entire floor space of the crawl.

What’s your R-value?

Below are the U.S. Department of Energy recommended minimum R-values for your climate zone.

Your Climate Zone: 4

    Attics 2x4 Walls 2x6 Walls Floors Crawlspaces
Zone 4 R38 to R60 R13 to R15 R19 to R21 R25 to R30 R25 to R30

Choosing the Right Insulation

Fiberglass insulation is sold in roll and batt form; both are available with or without kraft paper facing. Use the guide below to select the best insulation for your project.

  • Rolls

    Continuous rolls are easy to transport and can be cut to length; great for large areas.

  • Batts

    Batts come in pre-cut lengths for faster installation and each package contains more square feet than rolls; ideal for framed cavities.

  • Faced

    Faced insulation uses kraft paper vapor barriers to control moisture transmission between walls and floors.

  • Unfaced

    Unfaced insulation does not have a vapor barrier; can be used over existing insulation in the attic, or where moisture control is not needed.

To calculate how much you need:

Calculate Your Square Footage

A: Length of all walls added together

B: Height of wall

Your Square Footage: Sq Ft.

Recommended Products

The following products are recommended for use in crawlspace walls. Add items to your list, and you’ll be able to view, print or email your checklist when you’re done.

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Installation Tips

Installation Instructions

  1. First measure and cut small pieces of insulation and fit them snugly into the band joist or the area above the foundation wall.
  2. For the walls, the insulation should be cut long enough to cover the entire wall and extend 2' along the ground on the floor of the crawlspace. Use furring strips or cap nails to hold the insulation in place by nailing them to the sill.
  3. After the insulation has been installed, a 4- or 6-mil polyethylene ground cover should be placed over the entire crawl space floor. All joints / seams in the poly should be overlapped a minimum of 6" and sealed. The ground cover should run under the insulation and up the crawl space wall, on all sides, a minimum of 6" and be sealed to the wall.

NOTE: Check your local building codes for requirements in your area.

Basic Tools

  • Tape measure
  • Utility knife
  • Straightedge or 2 x 4 (for cutting insulation)
  • Lightweight, squeeze-type stapler

Protective Gear

  • Work gloves
  • Loose-fitting, long-sleeved shirt
  • OSHA-approved safety glasses
  • Disposable dust mask

Special Equipment

  • Portable work light


Before you begin any insulation project make sure you:

  • Seal any open penetrations
  • Gather the necessary tools and wear protective gear listed above
  • Always use a portable work light to ensure you have enough light in your work environment
  • Leave EcoTouch® PINK® insulation in its wrapper until you are ready to use it
  • Packaged insulation is highly compressed and expands greatly when the wrapper is opened

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