BASC Search | Building America Solution Center

Attic Air Sealing, Insulating, and Ventilating for Ice Dam Prevention

Information Guide

Information guide describing proper attic air-sealing, insulation, and ventilation to combat ice dam formation on roofs in cold climate zones.

Clean the attic floor of debris prior to installing new attic insulation. Use baffles to provide a path for ventilation air entering the attic from the soffit vents

Image

Right - Baffles are installed in attic to keep blown insulation from blocking soffit vents and ventilation path

Image

Baffles allow ventilation under roof decking while keeping wind from blowing insulation back from the edges of an attic.

Image

A simple vented attic with good air-sealing of the drywall ceiling air barrier, air flow from soffit vents to ridge vents protected by ventilation baffles, and lots of insulation covering the attic floor is unlikely to encourage ice dams.

Image

Right – Open-cell spray foam is installed over closed-cell spray foam in this hybrid approach to achieve adequate attic ventilation while allowing some vapor permeability.

Image

Ceilings and Attics

Reference

Information sheet with information about insulating and ventilating attics.

Unvented Attic Insulation

Guide

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

Blown Insulation for Existing Vented Attic

Guide

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

Batt Insulation for Existing Vented Attics

Guide

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

IRC FAQ: Conditioned Attics, GM-0905

Reference

Report discussing how to create livable space in the attic that meets IRC code requirements by either creating a ventilated roof assembly, or and unvented attic assembly.

Attic Radiant Barriers

Guide

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

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.

Attic Eave Minimum Insulation

Guide

Guide providing guidance on insulating attic eaves in new and existing single-family homes and multifamily buildings.

Right - The energy recovery ventilator ducts supply filtered outside air to multiple locations in the home and continuously exhaust stale air to provide clean, balanced ventilation.

Image

Air Sealing, Insulating, and Venting Attics and Roofs to Reduce Heat Gain

Information Guide

Information guide providing links to guides describing specific ways to air-seal, insulate, and ventilate attics and roofs to minimize heat gain in new and existing homes.