BASC Search | Building America Solution Center

Foundation wall exterior board insulation with above-grade wall insulation

Guide describing how to insulate a basement to improve the overall thermal performance of the building and provide more dry, usable conditioned space for home occupants and HVAC equipment.

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.

Stucco Over Rigid Foam Insulation

Guide describing how to install stucco over rigid foam insulation in new and existing homes.

Moisture can migrate from below the foundation to the basement wall and insulation cavity in a conventional blanket insulation installation

Publication Date

Thu, 10/26/2006 - 12:00

Wrong - Moisture from within the basement foundation wall can migrate into the insulation cavity in a conventional blanket insulation installation.

Publication Date

Thu, 10/26/2006 - 12:00

Right - Section view showing how to air-seal and insulate a basement wall with perforated blanket insulation by installing it over air-sealed rigid insulation board to reduce condensation risk in the fiberglass blanket.

Publication Date

Fri, 01/01/2021 - 12:00

Insulating a crawlspace foundation with “cripple wall” in warm climates; in Climate Zones 5+ replace the foil- or plastic-faced fiberglass batt/roll insulation with impermeable rigid insulation or closed-cell spray polyurethane foam

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.

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.

Publication Date

Fri, 01/01/2021 - 12:00

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

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

Vented crawlspace foundation insulated at floor joist with rigid foam.

Publication Date

Mon, 03/01/2021 - 12:00

To reduce the risk of condensation on the interior of the roof sheathing in cold weather, the ratio of exterior (above-deck) insulation must be increased as a percent of total attic insulation as outside temperature decreases

Publication Date

Sat, 10/01/2011 - 12:00

Unvented Conditioned Attic with Spray Foam Insulation Below Roof Deck

Guide describing a method for insulating an unvented attic by spraying foam insulation along the underside of the roof deck.

Water Managed Roof – Re-roofing and Adding Insulation Over a Sloped Roof

Guide describing how to re-roof an existing home with a sloped and add insulation above the roof deck.

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

Publication Date

Mon, 10/01/2012 - 12:00

New Code Options for Insulating, Sealing, and Controlling Moisture in Unvented Attics in Residential Buildings

Author(s)

Cole,

Lstiburek

Organization(s)

Pacific Northwest National Laboratory,

Building Science Corporation,

BSC

Webinar explaining new code options for insulating, sealing, and controlling moisture in unvented attics in residential buildings.

Technology Solutions Case Study: Field Testing an Unvented Roof with Fibrous Insulation and Tiles

Author(s)

Building Science Corporation

Organization(s)

BSC

Publication Date

February, 2016

Case study describing field testing of an unvented roof with fibrous insulation and tiles.

Right - This concrete basement wall has exterior rigid insulation and comprehensive moisture management details.

Publication Date

Tue, 09/01/2020 - 12:00

Technology Solutions Case Study: Retrofit Measures for Embedded Wood Members in Insulated Mass Masonry Walls

Author(s)

Building Science Corporation

Organization(s)

BSC

Publication Date

October, 2015

Case study describing retrofit measures for embedded wood members in insulated mass masonry walls.

R-5 XPS rigid foam exterior sheathing provides an air seal, moisture barrier, and additional insulation value.

Publication Date

Thu, 09/01/2011 - 12:00

Moisture-resistant rigid foam insulation was installed to provide a continuous air and thermal barrier behind the tub-shower insert.

Wrong – A clothes dryer that vents to the crawlspace can contribute moisture to the crawlspace; this can result in damp, molding, and rotting insulation

Right - the vapor barrier is extended up the sides of the piers in this crawlspace, which is sealed and insulated to house the HVAC ducts.

This farmhouse was retrofit by removing the existing siding and adding taped insulated sheathing and battens before installing new siding

Because the above-grade potions of the wall lack exterior insulation, condensation and even ice form during cold winter conditions

Publication Date

Thu, 08/31/2017 - 12:00

The Perfect Wall includes water, air, thermal, and vapor layers with continuous insulation exterior of the sheathing to reduce the condensation potential in the wall.

Publication Date

Thu, 07/15/2010 - 12:00

Masonry wall interior retrofit with fluid-applied water control layer and wood-framed wall with cavity insulation (climate zones 1-4 only)

Publication Date

Fri, 08/13/2021 - 12:00

Right – The air- and water-barrier material lining the shower stall is mastic sealed to prevent leakage and rigid foam insulation is installed on the floor of the shower.

Publication Date

Thu, 09/30/2021 - 12:00

Stucco is installed over rigid insulation, which is installed over a drainage plane consisting of a drainage gap and building wrap layer over the sheathing

Wrong - Air leakage from the conditioned space to the basement foundation wall can lead to condensation or moisture issues in a conventional blanket insulation installation.

Publication Date

Thu, 10/26/2006 - 12:00

On top of the ice-and-water shield, the builder installed horizontal beams that were raised 6 inches off the deck to allow room for spray foam insulation.

Foil-faced rigid foam and spray foam can be used to insulate a basement on the interior; use good moisture management techniques to keep the basement dry

Construction Guide - Next Generation High Performance Walls in Climate Zones 3-5, Part II: 2x4 Walls with 1” - 1.5” Exterior Insulative Sheathing

Author(s)

Kochkin Vladimir,

Wiehagen Joseph

Organization(s)

Home Innovation Research Labs,

HIRL

Publication Date

June, 2017

The Guide addresses walls constructed with 2x4 wood frame studs, wood structural panel (WSP) sheathing as wall bracing and added backing for foam sheathing, a layer of rigid foam sheathing insulation up to 1.5 in. thick over the WSP, and a cladding system installed over the foam sheathing in low...

Exterior fiberglass insulation on this new home was (incorrectly) cut to terminate below-grade after backfill, which will expose the above-grade portions of the foundation wall to cold temperatures

Publication Date

Mon, 10/01/2012 - 12:00

Wrong – Don’t use nails to fasten poly vapor barrier around flex ducts; it will allow moist air to reach the ducts where it could condense and ruin the insulation.

Publication Date

Tue, 04/13/2021 - 12:00

In warm-humid climates, do not install Class 1 vapor retarders on the interior side of air-permeable insulation in above-grade walls, except at shower and tub walls.

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

Publication Date

Fri, 08/13/2021 - 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.

When rigid foam insulation is applied to the exterior side of the wall cavity under the cladding, with seams taped and an air gap provided, it acts as a vapor barrier, air barrier, and rain screen.

Publication Date

Thu, 09/01/2011 - 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

The builder in this very cold climate installed three layers of unfaced mineral wool batt in the double wall with a code-required vapor barrier between the middle and inner layers of wall insulation that is taped to barriers in the ceiling and floor.

Retrofit an existing roof by installing rigid foam above the roof deck with a ventilation space between the rigid foam and the new roof sheathing plus new moisture and air control layers and cavity insulation in the roof rafters.

A paint-on waterproofing covers the exterior and tops of the concrete block foundation walls and piers to block moisture moving up through the concrete, while foil-faced R-13 insulation lines the inside surface of the exterior walls.

Publication Date

Fri, 01/01/2016 - 12:00

Right - Reduce condensation risks to blanket insulation by installing perforated vapor retarder covered fiberglass blankets over rigid foam that is air-sealed at all edges; staple the blanket to nailers and top/bottom plates and tape over the seams.

Publication Date

Fri, 01/01/2021 - 12:00

Wrong - Plastic-covered blanket insulation that is installed directly against concrete walls with no rigid foam or closed-cell spray foam covering the concrete could trap moisture coming through the concrete, leading to mold, moisture, and odor problems.

Publication Date

Thu, 10/26/2006 - 12:00

Controlling Moisture in Unvented Attics - Code Compliance Brief

Publication Date

May, 2017

The intent of this brief is to provide code-related information about controlling moisture in unvented attics by installing a vapor diffusion port/vent that would convey water vapor from an unvented attic to the outside when air-permeable insulation materials are installed and can be verified as being in compliance with the related codes and standards for residential construction. Providing consistent information to document compliance with codes and standards to all relevant parties responsible for verifying compliance (e.g., code officials, builders, contractors, designers, etc.) is expected to result in increased compliance and more timely, less challenging and more uniform plan review and field inspections.

Termite-Resistant Foundations and Walls

Guide describing techniques and measures for increasing the termite resistance of a home's foundations.

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.

Support at Intervals for Flex Ducts

Guide describing how to hang ducts with supporting straps or saddles to adequately support ducts so they do not sag and are not pinched or compressed in a manner that would cause damage to the ducts, the duct insulation, or the duct air barrier covering.

Condensation Control in Attics and Roofs in Cold Weather

Guide describing causes of condensation in attics and roof assemblies during cold weather and ways to reduce this condensation.

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.

Air Sealing Drywall to Top Plate

Guide describing ways to seal drywall to the top plate of an exterior wall to air-seal the wall cavity.

Moisture Management in Residential Construction Series - Building Enclosure: Window Installation

Publication Date

January, 2011

Author(s)

Home Innovation Research Labs

Organization(s)

Home Innovation Research Labs

Video describing the installation of windows to be air- and water-tight, including recommendations on flashing, air-sealing, and insulation, from Home Innovation Research Labs

Water Management of Existing Crawlspace Floor

Guide providing information about treating bulk water drainage issues and moisture control measures in existing basements and crawl spaces.

Moisture Management in Residential Construction Series - Building Enclosure: Exterior Wall Overview

Publication Date

January, 2011

Author(s)

Home Innovation Research Labs

Organization(s)

Home Innovation Research Labs

Video from Home Innovation Research Labs giving an overview of moisture problems common to exterior walls and how to mitigate these problems with proper framing, flashing, sheathing, cladding, and insulation.

They All Laughed, BSI-026

Author(s)

Lstiburek Joseph W

Organization(s)

Building Science Corporation,

BSC

Publication Date

January, 2017

Article describing the evolution of the IRC to permit class 3 vapor retarders (latex paint) in walls coupled with exterior continuous insulation to allow drying and reduce condensation risk.

Home Performance Assessment

Information guide describing how to apply a whole-house approach to home improvement with energy efficiency upgrades, improved indoor air quality, and increased comfort.

Mastic Home Exteriors Installation Guide

Author(s)

Ply Gem Siding Group

Organization(s)

Ply Gem Siding Group

Publication Date

April, 2015

Siding installation guide for Ply Gem Siding Group products.

Attic Radiant Barriers

Guide describing application of a radiant barrier layer in the attic to block radiant heat transfer between hot surfaces and heat-absorbing surfaces.

Air Sealing Bathroom and Kitchen Exhaust Fans

Guide describing how to air-seal bathroom and kitchen exhaust fans.

Aerosol Sealing Building Enclosures, Single and Multifamily Dwellings - Code Compliance Brief

Publication Date

January, 2020

The intent of this brief is to provide code-related information for aerosol sealing building enclosures to achieve durable air tightness levels that will be accepted as being in compliance with the code.

Managing Indoor Humidity and Ventilation in Cold Weather

Guide describing steps to take to minimize indoor humidity in preparation for cold winter weather.

Pre-Retrofit Assessment of Attics, Ceilings, and Roofs

Information guide describing things to consider in the attic, ceiling, or roof before attempting retrofits of items including HVAC, wiring, or structural systems.

Masonry wall interior retrofit with fluid-applied water control layer, spray foam, and wood or metal stud service cavity

Publication Date

Fri, 08/13/2021 - 12:00

Masonry wall interior retrofit with parge coat, fluid-applied water control layer, spray foam, and wood or metal stud service cavity

Publication Date

Fri, 08/13/2021 - 12:00

Masonry wall interior retrofit with fluid-applied water control layer, mineral wool rigid foam, and wood or metal stud service cavity (climate zones 1-4 only)

Publication Date

Fri, 08/13/2021 - 12:00

Airflow within drop-in ceiling assemblies is generally not a concern due to the limited vertical height. However, airflow within air gaps in walls is a concern due to the much larger vertical height.

Publication Date

Sat, 09/14/2024 - 12:00

Moisture Control Guidance for Building Design, Construction and Maintenance

Author(s)

Environmental Protection Agency

Organization(s)

EPA

Publication Date

December, 2013

EPA guidance document providing information on moisture control in buildings.

Masonry wall interior retrofit with parge coat, fluid-applied water control layer, mineral wool rigid foam, and wood or metal stud service cavity (climate zones 1-4 only)

Publication Date

Fri, 08/13/2021 - 12:00

When architects and builders think of the house as a systems, all of the parts are designed to work together for a healthy, durable home that minimizes builder callbacks while cutting energy, maintenance, and repair costs down the road.

Publication Date

Thu, 09/01/2011 - 12:00

Waverly Home Addition | Exterior Cladding Details

Publication Date

February, 2014

Video describing the exterior cladding details of a residential home addition project.

The builder installed 1.5 inches of soy-based spray foam on the outside of the walls over the OSB sheathing, then kept a ¾ inch gap between the foam and the brick veneer siding to allow moisture vapor from the bricks to dissipate.

Joni Mitchell, Water and Walls, BSI-071

Author(s)

Lstiburek Joseph W

Organization(s)

BSC,

Building Science Corporation

Publication Date

November, 2013

Article describing walls and moisture development on them.

Right: All joints in the rigid foam are taped to keep stucco out of joints for even drying. Mesh tape (shown here) is used with expanded polystyrene (EPS); acrylic sheathing tape or self-adhered membrane is used with XPS

Deep-Dish Retrofits, BSI-079

Author(s)

Lstiburek Joseph W

Organization(s)

Building Science Corporation,

BSC

Publication Date

August, 2014

Report covering exterior energy retrofits of masonry buildings.

Moisture Management in Residential Construction Series - Managing Water Vapor Flow

Publication Date

January, 2011

Author(s)

Home Innovation Research Labs

Organization(s)

Home Innovation Research Labs

Video from Home Innovation Research Labs on materials and design principles to mitigate moisture issues in homes.

Venting Vapor, BSI-088

Author(s)

Lstiburek Joseph W

Organization(s)

Building Science Corporation,

BSC

Publication Date

July, 2015

Guide providing information on controlling attic ductwork sweating.

Pre-Retrofit Assessment of Crawlspaces and Basements

Information guide describing things to consider in the basement or crawlspace before attempting retrofits of adjacent items including HVAC, wiring, or structural systems.

Hurricane Straps

Publication Date

September, 2020

Author(s)

FLASH Strong Home

Organization(s)

FLASH

Video describing hurricane ties and how they make your home more ready for severe weather by strengthening structural connections.

Flood-hardy, drainable, dryable wall

Publication Date

October, 2017

Video explaining a design option for homes in the case of a flood that would negate the need for gutting the home post-flood. Recommendations from LSU AgCenter.

Construction & Design Considerations in Warmer Climates

Author(s)

Zero Energy Project

Organization(s)

Zero Energy Project

Publication Date

January, 2022

Guidance from Zero Energy Project on construction techniques for warmer climates, such as home orientation, and insulation requirements.

Building America Building Science Advisor

Author(s)

Oak Ridge National Laboratory,

U.S. Department of Energy

Organization(s)

ORNL,

DOE

Publication Date

January, 2019

Web based tool providing decision-making guidance for selecting wall assembly components.

The goal of foundation moisture management is to construct the basement, crawlspace, or slab in a way that keeps moisture from getting in in the first place

Publication Date

Thu, 03/01/2012 - 12:00

Monitoring of Double-Stud Wall Moisture Conditions in the Northeast, BA-1501

Author(s)

Ueno Kohta

Organization(s)

Building Science Corporation,

BSC

Publication Date

January, 2015

Report on a study monitoring moisture conditions of double-stud wall assemblies with different insulation in Devens, Massachusetts.

Wrong – The gable end wall failed because the rigid foam sheathing was not backed up by plywood or OSB.

Publication Date

Wed, 12/01/2010 - 12:00

When condensation forms on the interior side of wall sheathing and is not able to dry out, it can lead to mold growth and rotting of wall sheathing and framing

Publication Date

Wed, 07/01/2020 - 12:00

Indoor airPLUS Version 2 Reaches for the Sky: New Opportunities for Healthier Multifamily Buildings

Author(s)

Nick Hurst,

Gayathri Vijayakumar,

Karla Butterfield

Organization(s)

EPA,

Steven Winter Associates,

EEBA

Publication Date

October, 2020

Webinar from a group of indoor air quality experts on compliance with EPA's Indoor airPLUS program as multifamily buildings reach past five stories high, with special consideration taken for ventilation, air sealing, moisture control, and indoor air quality needs in larger residences.

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.

Field Evaluation of Four Novel Roof Designs for Energy-Efficient Manufactured Homes

Author(s)

Dentz Jordan,

Ansanelli Eric,

Dadia D,

Levy Emanuel,

Barker Greg M,

Rath Pournamasi

Organization(s)

Advanced Residential Integrated Energy Solutions,

ARIES

Publication Date

December, 2015

Report of a field evaluation of four novel roof designs to see how each design would reduce space-conditioned energy use so that the knowledge gained could be applied to the design of new manufactured homes.

Disaster-Resistant Roof Venting

Guide describing the installation of roof vents that are resistant to damage from high winds and entry of wind-borne rain, wildfire embers, or pests.

Affordable Solid Panel "Perfect Wall" System

Author(s)

Schirber Tom,

Jacobson Rolf,

Mosiman Garrett,

Handeen Daniel,

Huelman Patrick H

Organization(s)

University of Minnesota,

UMN,

U.S. Department of Energy,

DOE,

NothernSTAR

Publication Date

February, 2022

Technical report describing the SPS (Structural Panel System), an innovative implementation of the "perfect wall" concept, situating environmental control layers on the exterior side of structural components for improved constructability, cost-effectiveness, and performance, validated through the...

Pre-Retrofit Assessment of Walls, Windows, and Doors

Information guide describing things to consider before retrofitting walls, windows, and doors, including wiring, moisture protection, and lead paints.

Moisture Performance of High-R Wall Systems

Author(s)

Kochkin Vladimir,

Shah Nay B

Organization(s)

Home Innovation Research Labs,

HIRL,

U.S. Department of Energy,

DOE

Publication Date

May, 2018

The next generation of building enclosures is a key step toward achieving high-performance goals through decreasing energy load demand and enabling advanced space-conditioning systems. Yet the adoption of high-R enclosures and particularly high-R walls has been a slow-growing trend because...