BASC Search | Building America Solution Center

Slab Edge Insulation

Guide describing how to insulate slabs on grade in climate zones 3 and higher.

Well insulated slab

Publication Date

Tue, 05/01/2012 - 12:00

Properly installed rigid insulation

Rigid Insulation Over Aggregate

DWG

PDF

Foil Bubble Pack: Subslab Insulation?

Author(s)

Fulger Don

Organization(s)

Home Energy

Publication Date

November, 2004

Article describing the effective R-values of various subslab insulation products, including foil bubble pack.

Exterior Insulation for Existing Foundation Walls

Guide describing how to insulate a new foundation wall or an existing foundation wall by adding rigid insulation to the exterior side.

Insulation for Existing Crawl Space Floors

Guide describing how to upgrade a crawlspace floor in an existing home by adding insulation.

Right – Insulated concrete forms (ICFs) provide the insulated stem wall for the slab-on-grade foundation for this SIP house.

Publication Date

Thu, 09/30/2021 - 12:00

Rigid insulation and water control layers are installed on the exterior of a flat foundation wall; spray foam insulates the rim joist

Publication Date

Mon, 07/01/2013 - 12:00

Exterior Edge Insulation for Existing Foundation Slabs

Guide describing how to install slab edge insulation when retrofitting existing slab-on-grade foundations.

EPS Foam Insulation | Madrona Passive House

Publication Date

December, 2014

Video discussing the EPS foam insulation used on the floor of a passive house.

Right - The slab-edge insulation is finished with stucco.

Publication Date

Mon, 09/30/2019 - 12:00

Right – Slab insulation extends to the top of the slab

Publication Date

Fri, 10/28/2011 - 12:00

Right – Slab insulation extends to the top of the slab

Publication Date

Fri, 10/28/2011 - 12:00

Spray Foam Interior Insulation for Existing Foundation Walls

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

Turned down concrete slab - 1 inch rigid insulation

DWG

PDF

Wrong – Slab insulation does not extend to the top of the slab

Publication Date

Fri, 10/28/2011 - 12:00

Wrong – Slab insulation does not extend to the top of the slab

Publication Date

Fri, 10/28/2011 - 12:00

Right - Potential locations for slab-on-grade stem insulation in new construction: slab insulation should always be underneath, with stem walls insulated (a) inside, (b) outside, (c) not at all, or (d) outside with underground extension to repel moisture.

Publication Date

Tue, 01/01/2013 - 12:00

Rigid Foam Insulation Installed over Existing Foundation Slabs

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

High-Performance Slab-on-Grade Foundation Insulation Retrofits

Author(s)

Goldberg Louise F,

Mosiman Garrett

Organization(s)

NorthernSTAR,

NSTAR,

University of Minnesota,

UMN

Publication Date

September, 2015

Report assessing slab-on-grade foundation insulation energy savings.

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.

Publication Date

Mon, 03/01/2021 - 12:00

Slab-on-grade with concrete stem wall and slab insulation

Organization(s)

BSC

Publication Date

May, 2009

Information sheet about insulating slabs.

Slab-on-grade with integral grade beam and exterior and slab insulation

This house with an insulated slab is protected from pests with a termite shield at the sill plate, borate-treated framing, insect screen covering bottom of furring air gap, and brick veneer over slab-edge insulation

Publication Date

Mon, 03/01/2021 - 12:00

Right - This rigid insulation is correctly installed in a level layer over aggregate; the seams will be taped

Right - Workers installed rigid foam on the floor and the sill plates of these pre-cast, pre-insulated concrete wall panels to provide a continuous layer of insulation under and around the not-yet-poured basement floor slab.

Publication Date

Thu, 09/30/2021 - 12:00

Rigid foam insulation and a thin slab were installed over the dirt and gravel of this sealed crawlspace

Organization(s)

IBACOS

Publication Date

October, 2013

Case study describing installation of exterior rigid foam insulation on a slab foundation.

The existing slab is retrofitted by coating with epoxy paint, then installing rigid foam insulation and a floating subfloor.

Publication Date

Mon, 07/01/2013 - 12:00

Right – Rigid foam was attached to the tops of the precast foundation walls to form an insulated edge for the floor slab.

Publication Date

Mon, 09/30/2019 - 12:00

Technology Fact Sheet Slab Insulation: Improve Comfort and Save Energy in Homes with Slab-on-Grade Floors

Author(s)

Southface Energy Institute

Organization(s)

DOE

Publication Date

December, 2000

Brochure describing insulation approaches for homes with slab-on-grade floors.

Capillary Break Beneath Slab - Polyethylene Sheeting or Rigid Insulation over Aggregate or Sand and Geotextile Mat

Guide describing how to install a capillary break under a slab foundation using either polyethylene sheeting or rigid insulation installed over aggregate or over sand and geotextile matting.

The builder’s crews spray foam directly onto the ground to provide a vapor barrier and insulation layer under the slab.

Right - Retrofit of an existing basement slab by adding dimple plastic mat, rigid foam insulation, and a floating subfloor.

Right - The existing basement slab is retrofitted by installing a dimple plastic drainage mat, rigid foam insulation, and a floating subfloor.

Publication Date

Mon, 07/01/2013 - 12:00

A concrete slab-on-grade foundation with exterior insulation, which can be elevated above the local grade as a flood-prevention strategy.

Publication Date

Tue, 01/01/2013 - 12:00

Externally insulated concrete slab-on-grade foundation with a turn-down footing, showing anchorage of the wall to the foundation for seismic resistance

For slabs on grade in CZ 4 and higher, 100% of slab edge insulated to ≥ R-5 at the depth specified by the 2009 IECC and aligned with thermal boundary of the walls

Publication Date

Sat, 10/01/2011 - 12:00

Concrete slab-on-grade foundation with a turn-down footing insulated on its top surface, showing anchorage of the wall to the foundation for seismic resistance

Publication Date

Tue, 08/24/2021 - 12:00

Externally insulated post-tensioned concrete slab-on-grade foundation wall with a turn-down footing showing anchorage of the wall to the foundation for seismic resistance

Publication Date

Tue, 08/24/2021 - 12:00

Externally insulated post-tensioned concrete slab-on-grade foundation wall with a turn-down footing showing anchorage of the wall to the foundation for seismic resistance

Publication Date

Tue, 08/24/2021 - 12:00

Spray foam extends down the foundation wall to the slab, which has been retrofitted by adding dimple plastic drainage mat and rigid foam insulation.

Publication Date

Mon, 07/01/2013 - 12:00

Right – After installing the insulated concrete foundation wall panels, the builder installed underslab rigid foam, which was topped by 4 inches of crushed rock then the poured slab.

Publication Date

Mon, 09/30/2019 - 12:00

The floor slab is completely insulated with ICF foundation walls and R-20 (3 inches) of closed-cell foam that is sprayed directly onto the ground before pouring the slab.

The basement slab is wrapped in a blanket of insulation including R-27 of closed-cell spray foam under the slab and R-22 ICF blocks wrapping the slab edges.

ICF foundation walls wrap the floor slab in R-22 of insulation while the entire space under the slab is covered with 4.3 inches of closed-cell spray foam.

Between the ICF foundation walls, the builder sprayed closed-cell spray foam directly onto the gravel base to provide a vapor barrier and continuous layer of insulation under the slab.

Publication Date

Thu, 01/01/2015 - 12:00

The foundation walls are ICF block providing two continuous layers (R-23) of insulation around the slab, which will sit on an additional 4 inches (R-20) of low-VOC EPS foam.

Brick veneer framed wall supported by a concrete slab-on-grade foundation with a turn-down footing insulated on its top surface, showing anchorage of the wall to the foundation for seismic resistance

Publication Date

Tue, 08/24/2021 - 12:00

Right - Additional potential locations for slab-on-grade insulation include (a) under the slab and outside the perimeter with optional underground moisture block, (b) under the whole foundation, or (c) on top of the slab.

Publication Date

Tue, 01/01/2013 - 12:00

The builder laid down a 4-inch base of aggregate rock, then covered that with a plastic vapor barrier that is taped at all seams and around all penetrations before installing the rigid foam under-slab insulation.

Spray foam insulation extends down the foundation wall to the slab, which has been retrofitted by cutting the slab to install drainage mat against the wall and a new perimeter footing drain, along with rigid foam plastic above the slab.

Publication Date

Mon, 07/01/2013 - 12:00

This Texas homes uses a slab foundation including a 4-in.-thick post-tensioned monolithic slab with turned-down edges poured over a 6-mil polyethylene vapor barrier and capillary break; slab edge insulation is not used due to termite risk.

Publication Date

Thu, 09/01/2011 - 12:00

Video describing the under slab and vapor barrier used on a passive house.

Good water management practices like sloping grade away from house, and installing gutters, perimeter drain pipe, a capillary break, and free-draining soils or drainage mat protect the foundation from water saturation.

Publication Date

Thu, 03/01/2012 - 12:00

Rigid foam wraps the exterior of the foundation slab.

The home’s slab-on-grade foundation is wrapped in a blanket of rigid foam extending completely under the slab and along the edges.

Right – R-20 of XPS and polyiso rigid foam were added on the slab shelf that is part of this precast foundation wall system.

Publication Date

Mon, 09/30/2019 - 12:00

Right – Workers pour the concrete for the basement floor slab over a vapor barrier installed over rigid foam.

Publication Date

Thu, 09/30/2021 - 12:00

The basement is constructed with precast concrete walls lined with R-21.3 foil-faced rigid foam while an R-10 layer of XPS rigid foam covers the ground under the slab.

Residential Buildings: Foundations

Author(s)

U.S. Department of Energy

Organization(s)

DOE

Publication Date

August, 2022

Website describing the U.S. Department of Energy's residential buildings program.

Right – This wall is constructed with the sill plate overhanging the top of the foundation wall so that when rigid foam is installed on the exterior of the foundation wall, its surface will align with the surface of the wall sheathing.

Publication Date

Mon, 09/30/2019 - 12:00

Polyethylene Over Aggregate

DWG

PDF

Right - Basement slab with a capillary break of either gravel or a drainage mat.

Publication Date

Thu, 02/01/2018 - 12:00

Polyethylene sheeting covers the aggregate and extends down and under the footing to provide a capillary break between the ground and the slab and monolithic footing

DWG

PDF

Spray foam extends down the inside of the foundation wall to the uninsulated slab; because the wall lacked exterior perimeter drainage, the slab was cut and an interior footing drain was installed.

Publication Date

Mon, 07/01/2013 - 12:00