To  :Icynene Licensed Dealers
From:Ed Reeves, Engineering Manager
Date:November 4, 2003
Re  :Unvented attics - Proposed Changes to the Building Codes

On September 11, 2003, the Department of Energy (DOE) submitted a proposal to
include unvented attics and crawl space designs to the International Energy
Conservation CodeŽ (IECC), International Existing Building CodeŽ   (IEBC),
International Mechanical CodeŽ (IMC), International Residential CodeŽ (IRC)
Building/Energy and International Residential CodeŽ  (IRC) Mechanical Code
Development Committees. This submission was made by the Department of Energy
(DOE) at the Public Hearings on Code Change Proposals at the International Code
Council (ICC) Forum in Nashville Tennessee. The proposal was accepted.

The acceptance of this code proposal is the first step towards having unvented attics
and crawlspaces included in the national code. The results of the public hearing
will be published for further public comment in November 200J. The deadline for
receipt of public comment is January 14, 2004 (Tentative). The publication date of
public comments "final action" agenda is April 1, 2004 (Tentative). The Public
Hearings for "Final Action Consideration" are tentatively scheduled for May 17-20
at the Sheraton Hotel, Overland Park, KS.

If the proposal is adopted the code change will be published in the 2004
supplement booklet of the existing standard. It will become part of the 2006
edition of the code.

Since the Department of Energy (DOE) submitted the proposal, there is tremendous
strength behind this initiative.

A copy of the Department of Energy proposal for unvented attics is attached. Use
it to support your local code efforts.

Add new Section after R806.4
Conditioned attic assemblies: Unvented conditioned attic assemblies (spaces
between the ceiling joists of the top story and the roof rafters) are permitted under the
following conditions:

1. No interior vapor retarders are installed on the ceiling side (attic floor) of the
unvented attic assembly.
2. An air-impermeable insulation is applied in direct contact to the
underside/interior of the structural roof deck. "Air-impermeable" shall be
defined by ASTM E 283.
Exception: In zones 2B and SB, insulation is not required to be air
3. In the warm humid locations as defined in N1101.2.1:
a. For asphalt roofing shingles: A 1 perm or less vapor retarder (determined
using Procedure B of ASTM E 96) is placed to the exterior of the structural
roof deck; i.e. just above the roof structural sheathing.
b. For wood shingles and shakes: a minimum continuous 1/4-inch vented air
space separates the shingles/shakes and the roofing felt placed over the
structural sheathing.
4. In zones 3 through 8 as defined in N1101.2 sufficient insulation is installed to
maintain the monthly average temperature of the condensing surface above
45°F. The condensing surface is defined as either the structural roof deck or the
interior surface of an air-impermeable insulation applied in direct contact to the
underside/interior of the structural roof deck. "Air-impermeable" is quantitatively
defined by ASTM E 283. For calculation purposes, an interior temperature of
68°F is assumed. The exterior temperature is assumed to be the monthly
average outside temperature.


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