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Cold Climate Building Techniques and Concepts: Vapor retarder

Video

Video from Cold Climate Housing Research Center showing how to correctly install a vapor retarder for best air leakage prevention.

Class I Vapor Retarders Not Installed in Above-Grade Walls in Warm-Humid Climate

Guide

Guide describing vapor retarder permeability, insulation interaction, and example construction in a hot-humid climate.

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

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

Reference

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.

Wrong – If a wall vapor retarder is needed, as in this cold-climate home, openings in the vapor retarder should be sealed with tape.

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This house design in the Hot-Humid climate uses a slab foundation, masonry walls, and an Exterior Insulation Finish System (EIFS) cladding.

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Brick wall assembly for a hot-humid climate with no Class I vapor retarder and with an air gap (drained cavity) to dissipate vapor driven into the wall by the sun.

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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

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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

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Right – Half-inch furring strips provide a rain screen and air gap between the weather-resistant membrane and the fiber cement siding on the exterior walls of this marine-climate home.

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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

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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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Cold Climate Building Techniques and Concepts: Vapor retarder

Class I Vapor Retarders Not Installed in Above-Grade Walls in Warm-Humid Climate

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

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

Wrong – If a wall vapor retarder is needed, as in this cold-climate home, openings in the vapor retarder should be sealed with tape.

This house design in the Hot-Humid climate uses a slab foundation, masonry walls, and an Exterior Insulation Finish System (EIFS) cladding.

Brick wall assembly for a hot-humid climate with no Class I vapor retarder and with an air gap (drained cavity) to dissipate vapor driven into the wall by the sun.

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

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

Right – Half-inch furring strips provide a rain screen and air gap between the weather-resistant membrane and the fiber cement siding on the exterior walls of this marine-climate home.

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

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.

High-Performance Slab-on-Grade Foundation Insulation Retrofits

Brick, Stucco, Housewrap and Building Paper, RR-0105

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

Condensation Control for Walls in Cold Weather

Moisture Control for Residential Buildings

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

Ducts Buried in Attic Insulation and Encapsulated

Water Managed Wall Systems, PA-0301

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

Flow-Through Assemblies, BSI-091

The Journal of Light Construction (JLC) Guide to Moisture Control

Inward Drive – Outward Drying, BSI-061

Hot Spot: Closed Crawlspace - Sealing the Ground Vapor Retarder to the Wall

ABTCO Estimating and Installation Guide

Understanding Vapor Barriers, BSD-106

Stump the Building Chump – Joe Lstiburek

Building Code Training - Residential Thermal Envelope - Air Sealing

2021 IBC and IRC Adopt Improved Vapor Retarder Requirements