BASC Search | Building America Solution Center

A typical Las Vegas hot-dry climate home made of wood frame construction and insulated with R-25 expanded polystyrene externally over a drainage plane, with an unvented wood frame insulated attic and roof assembly.

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Unvented Attic Insulation

Guide

Guide describing methods for insulating an unvented attic along the roof line.

Below Deck Spray Foam Insulation for Existing Roofs

Guide

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.

Unvented Conditioned Attic with Spray Foam Insulation Below Roof Deck

Guide

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

Avoiding Wet Roofs - Part I

Reference

Article describing the building science implications of insulating vented or unvented attics.

Avoiding Wet Roofs - Part II

Reference

Article describing the research into insulating vented versus unvented attics.

Right - This unvented crawlspace is insulated along interior walls with rigid foam and air-sealed by covering the floor with vapor retarder that is sealed to the rigid foam which is taped at the seams.

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Ping Pong Water and The Chemical Engineer, BSI-016

Reference

Article outlining moisture accumulation in open cell spray polyurethane foam.

Cool Hand Luke Meets Attics, BSI-077

Reference

Article describing the difference between conditioned or unvented attics and unconditioned or vented attics.

Air-Impermeable Insulation for Condensation Control in Unvented Attics, per IRC Table 806.5.

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Unvented roof assembly at rake retrofitted with spray foam installed along the underside of the roof deck and extended to the rake edge to insulate and air seal the attic

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Unvented roof assembly at eave retrofitted with rigid foam, spray foam, and taped top edge of existing house wrap or building paper

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Unvented roof assembly at rake retrofitted with a filler piece and taped top edge of existing house wrap or building paper to seal the top of wall-to-roof transition

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Unvented Insulated Sloped Roofs

Guide

Guide describing construction of unvented, sloped, insulated roof assemblies in high wind zone areas.

New Whole-House Solutions Case Study: Imagine Homes: Stillwater Ranch, San Antonio, TX

Case Study

Case study describing a new home builder that strives to address health, safety, and durability issues in a hot and humid climate.

Vented versus Unvented Attic

Guide

Guide describing options for insulating and air sealing at either the attic floor or along the roof line in new homes.