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Outgassing of SBS Modified Roofing Materials

Lauren Gerard | Posted in General Questions on

I have an older home with a flat roof that needs to be replaced. I have severe multiple chemical sensitivities and I’m very concerned about outgassing of the materials into my attic space and ultimately migrating into the living space.

One contractor is sensitive to this issue and wants to use theTamko SBS Modified Roofing System, with the self adhesive application. I was given a sample of the base and cap sheets, and reacted very badly to them. I have looked at the application instructions, and noticed that it is recommended that ASTM D 41 wood primer should be applied to the decking prior to installation of the base and cap sheets.

Does anyone have experience with these products; how much and how strongly they outgas; and does anyone have experience with these, or similar products, in a home with a chemically sensitive person.

The contractor felt that if the system was applied on a very cool day, that everything should cure in a matter of days and be fine. Being chemically sensitive, I know that such an assessment can be very naive, as it can take weeks, months or even years for many products not to offend.

Any information is greatly appreciated.


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  1. Keith Gustafson | | #1

    have you considered EPDM?

    Normally it is adhered to ISO board with contact cement, which would doubtless require you to evacuate for several days, but they do have a water based adhesive that may be better for you.

    In reality, if the crew is very careful with the tools and cleanup, the glue is actually dry before the membrane goes down, and in my experience there is no smell[I know, lower standard than what you need] so I would think with such a short outgas time this would be a good product. There is also PVC and TPO, which I am not as familiar with

  2. Michael Lichy | | #2

    SBS modified-asphalt roof systems perform very well when properly designed and installed. They will typically outlive single ply roof systems such as TPO, EPDM, PVC.

    To things that you have mentioned that I am not crazy about: Self-adhering modified asphalt cap sheets and applying a modified-asphalt membrane directly to a wood roof deck.

    When I design a modified-asphalt roof system on a residence where the roof deck is wood and when the insulation is located between the roof rafters, I have designed the following (from the wood deck up):
    Crickets and Saddles to help drain the roof
    A glass-fiber, fire-resistant slip sheet
    5/8" DensDeck Prime(Fire-Barrier)
    Torch-grade modified-asphalt base sheet
    Torch-grade modified-asphalt cap sheet

    I have also used a self-adhering modified-asphalt base sheet. When I used a self-adhering base sheet, I will typically eliminate the slip sheet.

    Michael H. Lichy
    [email protected]
    RC Lichy & Associates, Inc.

    Roofing and Waterproofing Consultants.

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