BASC Search | Building America Solution Center

Ducts Buried in Attic Insulation

Guide describing buried ducts in loose-fill attic insulation, a method that can only be used in dry climates.

Rigid Insulation Over Aggregate

Batt Insulation for Existing Vented Attics

Guide describing how to increase insulation in existing homes by installing batt insulation on the ceiling plane of a vented attic.

Blown Insulation for Existing Vented Attic

Guide describing how to insulate a vented attic in an existing home using blown insulation added to the attic floor.

Ducts Buried in Attic Insulation and Encapsulated

Guide describing approaches to burying and encapsulating ducts in unconditioned attics to increase the overall R-value of duct insulation.

Spray Foam Insulation Applied to Existing Attic Floor

Guide describing how to apply spray foam insulation to ceilings in existing homes.

Below Deck Spray Foam Insulation for Existing Roofs

Guide describing how to add spray foam insulation to the underside of the existing roof deck as part of the conversion of a vented attic to an unvented, insulated attic.

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.

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.

Publication Date

Thu, 09/30/2021 - 12:00

Typical R-values and Vapor Retarder Classifications for Common Insulation Materials

Typical R-values for common insulation materials are summarized in this table, which also identifies the vapor retarder classification for each insulation.

Technology Solutions Case Study: Moisture Durability of Vapor Permeable Insulating Sheathing

Author(s)

Building Science Corporation

Organization(s)

BSC

Publication Date

October, 2013

Case study describing research about using exterior, vapor permeable insulation of retrofit walls with vapor permeable cavity insulation.

Walls in cold climates with a polyethylene vapor barrier interior of the wall cavity should have either no exterior insulation or a vapor-open continuous insulation like mineral wool that allows drying to the exterior

Publication Date

Sun, 01/15/2017 - 12:00

Right – Prepoured foundation panels with integrated insulation and vapor barrier are installed in place.

Publication Date

Mon, 09/30/2019 - 12:00

Wrong - Duct insulation and vapor barrier do not cover all of the flex duct.

Publication Date

Fri, 12/07/2018 - 12:00

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

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.

Rigid foam insulation can serve as the drainage plane when all seams are taped. Furring strips provide an air gap behind the cladding.

Publication Date

Sun, 04/01/2012 - 12:00

Wrong - The fiberglass blanket insulation has no perforated vapor retarder, does not cover the entire basement wall, is not sealed at the edges, and is not installed over rigid foam.

Publication Date

Fri, 01/01/2021 - 12:00

Vapor-permeable mineral wool insulation is installed on the exterior side of the sill beam during an exterior wall retrofit to allow the sill beam to dry to the outside

Walls in cold climates with a Class 3 vapor retarder (latex paint) and a vapor-open continuous insulation like mineral wool allow drying to the interior or the exterior

Publication Date

Sun, 09/20/2020 - 12:00

Masonry wall interior retrofit with parge coat, fluid-applied water control layer, rigid mineral wool, wood-framed wall with cavity insulation, smart vapor barrier, and wood or metal service cavity

Publication Date

Fri, 08/13/2021 - 12:00

Right – The raised slab foundation has a 3-ft stem wall of filled concrete block, then is back-filled with compacted dirt and crushed rock, then insulated with 1” rigid foam covered with taped vapor barrier, under a floor slab.

Publication Date

Mon, 09/30/2019 - 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

Vinyl Siding with Integrated Rigid Foam for Existing Walls

Guide describing the design and installation considerations for recladding of above grade walls using insulated vinyl siding.

Condensation Control for Walls in Cold Weather

Guide describing ways to construct wall assemblies in cold climates to minimize the likelihood of condensation formation inside the walls.

Water Managed Existing Sill Beams and Sill Plates

Guide describing how to insulate the sill beam or sill plate on the exterior side in a way that allows drying to the exterior, as part of an exterior wall upgrade.

Passive House Underslab Foam & Vapor Barrier: Karuna Video #6

Publication Date

February, 2012

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

Building Code Training - Residential Thermal Envelope - Air Sealing

Author(s)

Southface Energy Institute

Organization(s)

SEI

Publication Date

May, 2020

Presentation describing the Georgia State Minimum Standard Energy Code air barrier requirements, envelope concepts including air flow and thermal properties, and common missed insulation and air-sealing opportunities.

Wrong - Polyethylene sheeting should be lapped up sides of walls and pillars and taped

Right-Polyethylene sheeting is correctly installed over aggregate and taped to pillars and foundation wall

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

Polyethylene Over Aggregate

DWG

PDF

The Larsen-truss 9-inch wall cavities were covered with a smart vapor membrane that was fastened to the trusses with furring strips, which also provide an air gap behind the wood siding; each truss cavity is then filled with blown cellulose.

Publication Date

Wed, 12/29/2021 - 12:00

Flow-Through Assemblies, BSI-091

Author(s)

Lstiburek Joseph W

Organization(s)

Building Science Corporation,

BSC

Publication Date

January, 2016

Article discussing flow-through assemblies of walls.

The “institutional” perfect wall works in all climate zones; water, air, vapor, and thermal control layers are exterior of the sheathing, assembly allows drying to interior and exterior

Publication Date

Thu, 07/01/2010 - 12:00

2021 IBC and IRC Adopt Improved Vapor Retarder Requirements

Author(s)

Crandell Jay H

Organization(s)

Applied Building Technology Group,

ABTG

Publication Date

February, 2021

Article describing vapor retarder requirements in the International Residential Code and International Building Code 2021.

This exterior wall retrofit permits drying to the exterior of a sill plate installed on an untreated irregular foundation wall

Publication Date

Mon, 07/01/2013 - 12:00

This exterior wall retrofit permits drying to the exterior of a sill plate installed on an untreated flat foundation wall

Publication Date

Mon, 07/01/2013 - 12:00

Moisture Control for Residential Buildings

Author(s)

Lstiburek Joseph W

Organization(s)

Building Science Corporation,

BSC,

U.S. Department of Energy,

DOE

Publication Date

September, 2020

Report providing extensive guidance on controlling moisture in building envelopes through proper selection and installation on air, water, thermal, and vapor barriers.

Construction Guide - Next Generation High Performance Walls in Climate Zones 3-5, Part I: 2x6 Walls

Author(s)

Kochkin Vladimir,

Wiehagen Joseph

Organization(s)

U.S. Department of Energy,

DOE,

Home Innovation Research Labs,

HIRL

Publication Date

June, 2017

Part I of the Guide addresses walls constructed with 2x6 wood frame studs, wood structural panel (WSP) sheathing as exterior sheathing, gypsum board as interior sheathing, and a cladding system installed over WSP sheathing in low-rise residential buildings up to three stories in height.