1900 SW 4th Ave, Portland, OR 97201
|Appeal ID: 4996||Project Address: 708 NW Skyline Crest Rd|
|Hearing Date: 3/26/08||Appellant Name: Teos Abadia|
|Case No.: B-013||Appellant Phone: 503-206-7319|
|Appeal Type: Building||Plans Examiner/Inspector: Steve Ault|
|Project Type: residential||Stories: 2 Occupancy: R3 Construction Type: Wood Frame|
|Building/Business Name: Abadia Residence||Fire Sprinklers:|
|Appeal Involves: Alteration of/additional to an existing structure||LUR or Permit Application No.: 07-168477|
|Plan Submitted Option: pdf [File 1]||Proposed use: Bedroom addition to single-family home|
N1104.9.1 Vapor barriers
This appeal is to waive the requirement for a vapor barrier/retarder. The building code requirement is as follows:
Vapor barriers shall be installed on the warm side (in winter) of all insulation as specified in this subsection.
In addition, and relevant to the appeal, the 2003 and 2006 IECC have very limited language addressing vapor retarders. Both read the same.
It is Section 402.5 in the 2006 edition, which states "The building design shall not create conditions of accelerated deterioration from moisture condensation. Above-grade walls, floors and ceilings not ventilated to allow moisture to escape shall be provided with an approved vapor retarder. The vapor retarder shall be installed on the warm-in-winter side of the thermal insulation. Exceptions: 1. In construction where moisture or its freezing will not damage the materials. 2. Frame walls, floors and ceilings in jurisdictions in Zones 1 through 4. (Crawl space floor vapor retarders are not exempted.) and 3. Where other approved means to avoid condensation are provided.
This section was rewritten in the 2007 IECC Supplement, which will be incorporated into the 2009 IECC Code when published.
The IECC also has Section 103.1 which states "This code is not intended to prevent the use of any material, method of construction, design or insulating system not specifically prescribed herein, provided that such construction, design or insulating system has been approved by the code official as meeting the intent of this code and literature from the material manufacturer on the proper installation and use of their specific product can be persuasive in supporting such alternate method.
|Code Modification or Alternate Requested|
This is a bedroom addition to an existing home (see page 7 of the plans). The construction is being provided by Arciform (phone: 971-230-0045). The appeal concerns the vapor barrier requirement for the exterior walls of a new bedroom on the second floor. The exterior wall cavities have been completely filled with GreenFiber Cocoon spray-applied cellulose insulation. Cellulose is an excellent insulator, providing a high R-Value, completely filling the wall cavity, preventing air transfer, and having preferred environmental qualities. The exterior wall is otherwise typical, and the drywall will be painted with a VOC-free paint (PVA paint is not desired due to the effect on the cellulose insulation noted below, as well as the PVA paint’s toxicity).
The recommendation of GreenFiber and all other cellulose manufacturers is that cellulose insulation be installed without a vapor barrier/retarder. This recommendation has been made for at least 20 years. The overwhelming body of evidence reveals that vapor retarders may often be unnecessary with any insulation, and are certainly inappropriate for spray-applied cellulose insulation. (Please see attachments for manufacturer comments and studies).
From the manufacturer: “Because of its mass density (high airflow resistance) and hygroscopic properties (moisture holding), GreenFiber Cocoon Insulation has the capacity to store up to 30% of its weight in moisture vapor while retarding its passage by air movement. In other words, it retards the flow of moisture vapor, and performs best when moisture vapor is allowed to enter or exit from either side. The chance of any significant amount of moisture vapor actually passing completely through from one side of the insulation to the other is highly unlikely given the dynamics of our daily environment. Even if enough moisture vapor were present to freeze on the exterior sheathing, GreenFiber Insulation would absorb it again as it melted. Make no mistake, GreenFiber Insulation is not classified as a vapor retarder, since it cannot be tested by ASTM E96; the only recognized test method for classifying vapor retarders. On the other hand, GreenFiber Insulation does meet the criteria on an exception since it creates an alternative construction where moisture or its freezing will not damage the materials.“
|Reason for alternative|
The recommendations of this and other cellulose manufacturers is to not install a vapor retarder with cellulose insulation. In addition, historical and recent materials science prove that a vapor retarder is not needed with cellulose insulation.
From the manufacturer: “When applied within exterior walls, we do not recommend the use of a vapor retarder on the warm-in-winter side, primarily due to GreenFiber's mass density and hygroscopic properties. This application without a vapor retarder is considered an alternate method under the provisions of Section 106 of the 1999 National Building Code (NBC), relating specifically to Chapter 13 and Section 723.3.1 and additionally to Sections 101.2 and 103.1 of the International Energy Conservation Code.”
The City of Portland Bureau of Development Services, in its publication The Plans Examiner, March 2007 (see attached or http://www.portlandonline.com/shared/cfm/image.cfm?id=149882 ), recognized the problem, stated that airflow is the primary concern, and stated that cellulose is an effective alternative:
“In recent years, further research and a more complete understanding of moisture and air dynamics in residential buildings has lead to additional effective moisture control strategies. Research has shown that water vapor diffusion driven by vapor pressure is not a major transport mechanism in Portland’s mild marine climate. That is because indoor vapor pressures are not very high for most of the year. Rather, air leakage is the primary way that water vapor is transported from indoor spaces into the structure.”
In addition to the above recommendations, the attached documents contain the results of many studies showing that countless numbers of homes with cellulose insulation and no vapor retarder have been found to contain no moisture problems.
1. Vapor barriers: Granted as proposed.