SBS Modified Bitumen Roof Membrane

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BESWUFI
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SBS Modified Bitumen Roof Membrane

Post by BESWUFI » Tue Dec 01, 2015 6:06 pm -1100

Could anyone help me determine the WUFI Material Properties I should use to user define a generic SBS Modified Bitumen Roof Membrane (ideally) or point me to the best substitute for one that is preexisting in the WUFI Pro database?

Thank you very much for your help!

Christian Bludau
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Re: SBS Modified Bitumen Roof Membrane

Post by Christian Bludau » Tue Dec 01, 2015 11:59 pm -1100

Bitumenous roofing felts have sd-values between something like 100 and 300 meters, can be more for alucoated or something like that.
In the generic database there is a "Roof Membrane V13" which is a bituminous felt with sd = 100m.

Christian

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Re: SBS Modified Bitumen Roof Membrane

Post by BESWUFI » Wed Dec 02, 2015 4:18 am -1100

To be specific the products I am looking to represent in the model are the Firestone SBS FR Cap (http://technicaldatabase.fsbp.com/downl ... pid=765%5D) and the Firestone SBS Polybase (http://technicaldatabase.fsbp.com/downl ... pid=765%5D).

When I hear the term bituminous felt, I think of a product more like a 30 pound felt (https://www.tamko.com/docs/documents-da ... f?sfvrsn=2).

Is the Roof Membrane V13 bituminous felt able to represent the Firestone products with relatively good accuracy? Or is it more like the #30 felt product?

Thanks!

Christian Bludau
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Re: SBS Modified Bitumen Roof Membrane

Post by Christian Bludau » Wed Dec 02, 2015 4:33 am -1100

For the hygrothermal calculation mainly the sd-value/ permeability and the surface color are from interest. The weight has no real influence because of the thin layer.
Unfortunately your datasheet does not give a permeability value.

So you can use the V13 but you should adapt the water vapor diffusion value / permeability.

Christian

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