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Concrete masonry basement wall with exterior insulation.

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Basement foundation insulated on interior with rigid foam.

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Wrong - This batt insulation is not aligned with the subfloor and joists.

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Right - The blanket fiberglass insulation is installed over a continuous layer of rigid foam insulation; the fiberglass is covered with a vapor retarder that is tape sealed at the seams.

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Spray Foam Interior Insulation for Existing Foundation Walls

Guide

Guide describing how to insulate an existing foundation wall by adding spray foam insulation to the interior side of the wall.

Right - A continuous layer of rigid foam insulation is installed against the foundation, and the perforated fiberglass insulation blanket is installed over that and covered with a semipermeable facing.

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Rigid Foam Board Insulation for Existing Band Joists

Guide

Guide describing principles of insulating and air sealing band joists as a stand alone energy upgrade, or as part of creating a closed crawlspace.

Foundation wall interior rigid insulation with furring strips

CAD File

Right – The rim joists above the pre-insulated basement walls are sealed and insulated with spray foam to prevent air leakage at this juncture in the building envelope.

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Foundation wall interior rigid insulation with framed wall

CAD File

Right - This poured concrete basement wall is insulated on the exterior and under the slab with rigid insulation; footing details include interior and exterior footing drain pipe.

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No Vapor Retarders on Interior Side of Air-Permeable Foundation Insulation

Guide

Vapor retarder plastic should not be installed over fibrous insulation on basement or crawlspace walls; rigid foam or spray foam should be installed directly against the concrete, behind the blanket insulation.

Rigid Foam Insulation Installed over Existing Foundation Slabs

Guide

Guide describing how to insulate an existing slab floor by adding rigid foam insulation over the slab then installing a floating subfloor.

Right – The basement of this cold-climate home is insulated along interior walls with 2 inches of foil-faced rigid foam; finished basement walls also have a 2x4 interior wall insulated with R-19 blown-in fiberglass insulation and a poly vapor barrier.

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Assembly Sequence for Concrete Wall with Interior Foam Spray Insulation

Video

Video animation showing an assembly sequence for a concrete basement wall with interior spray foam insulation.

This exterior insulated slab-on-grade monolithic grade beam foundation is protected from pests by termite shield at the sill plate, borate-treated framing, flashing at end of wall insulation, brick veneer over slab-edge insulation, and rock ground cover.

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UMN NorthernSTAR: DOE Building America: Exterior Foundation Insulation

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Video describing an “excavationless” retrofit technique developed by the University of Minnesota to install exterior insulation around the foundation of an existing home by using high-pressure water to cut a trench through the dirt along the edge of a concrete foundation, remove the mud with a...

Right - Basement with interior semi-permeable XPS or EPS insulation.

The rim band connecting the insulated precast concrete basement walls to the floor joists above is spray foamed to provide air-sealing and insulation in this hard-to-seal juncture.

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Moisture problems must be dealt with before sealing and insulating a crawlspace

This floor assembly above a vented crawlspace controls vapor and heat transmission by using foil-faced isocyanurate rigid foam insulation installed underneath the floor joists and fiberglass insulation in the floor joist cavities

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Concrete masonry basement wall with exterior insulation.

Basement foundation insulated on interior with rigid foam.

Wrong - This batt insulation is not aligned with the subfloor and joists.

Right - The blanket fiberglass insulation is installed over a continuous layer of rigid foam insulation; the fiberglass is covered with a vapor retarder that is tape sealed at the seams.

Spray Foam Interior Insulation for Existing Foundation Walls

Right - A continuous layer of rigid foam insulation is installed against the foundation, and the perforated fiberglass insulation blanket is installed over that and covered with a semipermeable facing.

Rigid Foam Board Insulation for Existing Band Joists

Foundation wall interior rigid insulation with furring strips

Right – The rim joists above the pre-insulated basement walls are sealed and insulated with spray foam to prevent air leakage at this juncture in the building envelope.

Foundation wall interior rigid insulation with framed wall

Right - This poured concrete basement wall is insulated on the exterior and under the slab with rigid insulation; footing details include interior and exterior footing drain pipe.

No Vapor Retarders on Interior Side of Air-Permeable Foundation Insulation

Rigid Foam Insulation Installed over Existing Foundation Slabs

Right – The basement of this cold-climate home is insulated along interior walls with 2 inches of foil-faced rigid foam; finished basement walls also have a 2x4 interior wall insulated with R-19 blown-in fiberglass insulation and a poly vapor barrier.

Assembly Sequence for Concrete Wall with Interior Foam Spray Insulation

This exterior insulated slab-on-grade monolithic grade beam foundation is protected from pests by termite shield at the sill plate, borate-treated framing, flashing at end of wall insulation, brick veneer over slab-edge insulation, and rock ground cover.

UMN NorthernSTAR: DOE Building America: Exterior Foundation Insulation

Right - Basement with interior semi-permeable XPS or EPS insulation.

Rigid insulation is installed on the exterior side of the flat foundation wall

Wrong - Sub-floor insulation is not properly installed or supported.

Right - Sub-floor insulation is properly installed and supported.

Rigid Foam Board Interior Insulation for Existing Foundation Walls

The rim band connecting the insulated precast concrete basement walls to the floor joists above is spray foamed to provide air-sealing and insulation in this hard-to-seal juncture.

Moisture problems must be dealt with before sealing and insulating a crawlspace

Wrong - Sub-floor insulation has gaps, compression, and misalignment.

Keeping The Heat In - Chapter 6: Basement Insulation Floors, Walls and Crawl Spaces

Exterior XPS basement insulation is correctly installed to completely cover the foundation wall

Unvented air-sealed crawlspace is insulated along the perimeter walls with rigid foam

UAF Cooperative Extension Service: Radon Mitigation in Super-Insulated Slab

This floor assembly above a vented crawlspace controls vapor and heat transmission by using foil-faced isocyanurate rigid foam insulation installed underneath the floor joists and fiberglass insulation in the floor joist cavities