Thread: Cardboard as a foam backer in attic?

Recent inspection on new construction the builder used cardboard to seperate the attic space over the garage as a backer for foam insulation application. My concern is the exposed cardboard backer, as a part of the insulation assembly shouldn't it at least meet the flame spread charecteristic required for the foam? Fl code apps?

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I've seen treated paper product insulation stop/venting channel at the soffit stapled to the trusses. It had a wax type of coating.
Was this used to separate the garage from habitable area? I/E gas fume barrier?

Originally Posted by M NEWMAN

I've seen treated paper product insulation stop/venting channel at the soffit stapled to the trusses. It had a wax type of coating.
Was this used to separate the garage from habitable area? I/E gas fume barrier?

The builder used the cardboard to seperate the area above the garage from the area above the conditioned area of the home. The foam insulation is applied to the underside of the roof deck and to the cardboard on one side only. I am concerned about the exposed face of the cardboard over the garage in the attic.

2009 IRC

R316.4 Thermal barrier.
Unless otherwise allowed in Section R316.5 or Section R316.6, foam plastic shall be separated from the interior of a building by an approved thermal barrier of minimum 1/2 inch (12.7 mm) gypsum wallboard or a material that is tested in accordance with and meets the acceptance criteria of both the Temperature Transmission Fire Test and the Integrity Fire Test of NFPA 275.

Originally Posted by Matthew Brewer

2009 IRC

R316.4 Thermal barrier.
Unless otherwise allowed in Section R316.5 or Section R316.6, foam plastic shall be separated from the interior of a building by an approved thermal barrier of minimum 1/2 inch (12.7 mm) gypsum wallboard or a material that is tested in accordance with and meets the acceptance criteria of both the Temperature Transmission Fire Test and the Integrity Fire Test of NFPA 275.

Thank you for the response the issue at hand is not related to the fire seperation between the interior and the foam. It is with respect to the exposed cardboard in the attic as a part of the foam insulation assembly.

Originally Posted by Brian Hoagland

Thank you for the response the issue at hand is not related to the fire seperation between the interior and the foam. It is with respect to the exposed cardboard in the attic as a part of the foam insulation assembly.

The bigger issue is the exposed foam, not the exposed cardboard.

Originally Posted by Brian Hoagland

Thank you for the response the issue at hand is not related to the fire seperation between the interior and the foam. It is with respect to the exposed cardboard in the attic as a part of the foam insulation assembly.

Originally Posted by Fred Weck

The bigger issue is the exposed foam, not the exposed cardboard.

The foam insulation is required to be protected by a thermal barrier unless it is protected by an ignition barrier. This is an ongoing and evolving issue as to how to address what aspects in what why.

Currently, the most often accepted way is for an ignition barrier coating to be spray applied over the foam, although that may not be a technically correct code approved method.

The cardboard needs to be removed, install studs, drywall, then spray the foam on the drywall.

I should add ... BOTH the cardboard AND the exposed spray foam are hazards, but in different ways.