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Indoor airPLUS

Technical Guidance to the Indoor airPLUS Construction Specifications

1. Moisture Control

Sections 1.1 - 1.4: Water-Managed Site and Foundation

1.3 Damp-proof Foundation

Damp-proof or waterproof exterior surfaces of below-grade foundation walls as follows:

  • Poured concrete, concrete masonry and insulated concrete forms (ICFs) shall be finished with a damp-proof coating; AND
  • Wood-framed walls shall be finished with trowel-on mastic and polyethylene or with other waterproofing demonstrated to be equivalent.

Exceptions: Houses without below-grade walls.


Coating the exterior of below-grade walls with asphalt emulsion, modified cement coatings, or other waterproofing helps to keep below-grade water from wicking and seeping through foundation walls. It is important to provide a barrier to water entering foundation walls to prevent a moisture source that would foster the growth of mold in the home.


The surfaces of concrete masonry block walls must be coated with a layer of parging before dampproofing can be applied. This coating fills the large pores in the block, providing a smoother surface to accept the dampproof coating. Dampproofing may be brush- or roller-applied, or may take the form of a spray-on coating, or closed-cell polyurethane foam.

While most contractors understand that concrete blocks require dampproofing, not all contractors realize that dampproofing is also required for most poured-concrete foundation walls. Dampproof coatings may be applied to poured concrete walls by brush/roller or by spraying. However, cast-in-place concrete can also be formulated to provide capillary-break qualities. Using admixtures and replacing some portion of the cement with pozzolan. The concrete mixture can be customized to yield concrete that is impermeable to liquid water migration.

Dampproofing insulated concrete forms (ICF) and waterproofing permanent wood foundations requires specialized methods. See manufacturer’s instructions.

References/Additional Information

  • Builder’s Foundation Handbook. National Program for Building Thermal Envelope Systems and Materials. Oak Ridge National Laboratory. ORNL, May, 1991. See www.ornl.gov/.
  • Permanent Wood Foundations - Design and Construction Guide, Southern Pine Council, 2000. See http://newstore.southernpine.com/cgi-bin/newsopine/product?;32 exiting epa
  • National Association of Home Builders - Research Center; Online information services; "Toolbase Services"; Foundations, Design and Construction Guides. See www.toolbase.org/ exiting epa.

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