BCAB #1762 - Unvented Roof Space, Article

March 19, 2015

BCAB #1762

Re: Unvented Roof Space, Article

Project Description

The project in question is a new single family dwelling. A roof deck over habitable space is proposed to be insulated with “two pound” spray foam applied between the joists with no venting between the insulation and the underside of the sheathing.

Reason for Appeal

Article requires a vented space between the top of the insulation and the underside of the roof sheathing for the transfer of moisture to the exterior “except where it can be shown to be unnecessary.”

Appellant's Position

The appellant considers he has provided adequate documentation to support his position that spray foam insulation applied directly to the underside of the roof deck between the joists removes the need to provide ventilation and is in conformance with the acceptable solution in Article The documentation included material such as a recent research report on mold growth in Code conforming vented attics, published by the Homeowner Protection Office, information from the ASHRAE Handbook of Fundamentals, an Ontario Buildings Branch opinion regarding the exclusion of ventilation requirements for roof spaces, a description of the characteristics of spray foam insulation, an analysis of the Code objectives related to Article, the air permeability of the spray foam insulation, the successful history of spray foam throughout North America and the acceptance of unvented spray foam roof assemblies in the US International Residential Code.

Building Official's Position

The building official maintains the appellant has not provided sufficient scientific evidence and testing by an accredited agency regarding this type of specialized roof assembly especially in an onsite uncontrolled environment. The building official contends the review/acceptance of an unvented roof assembly is the responsibility of the authority having jurisdiction. The building official also contends that the mandate of the Building Code Appeal Board is limited to the interpretation of the Code and does not include the approval of systems or products which are not specifically referenced. The acceptance of alternative materials and alternative methods of design and construction procedures is the sole purview of the local authority having jurisdiction.

Appeal Board Decision #1762

The Board considers that this dispute regarding the interpretation of Article falls within its jurisdiction because it describes an acceptable solution. Standards for spray foam insulation and its installation are referenced in Clause and Sentence respectively and spray foam insulation can be an acceptable material provided it conforms to these standards.

It is the determination of the Board that sufficient documentation has been provided by the appellant to demonstrate that, in accordance with Article, a vented space between the top of the spray foam insulation and the underside of the roof sheathing is unnecessary.

Lyle Kuhnert, Chair