Asphalt Shingle Roof System

[Sushmit Shreyans]

Hi All,

I am trying to model and reproduce the roof systems as simulated in an article titled "Compact Asphalt Shingle Roof Systems: Should They be Vented?" by Nelson and der Ananian.

The authors have discussed the model construction but there are a few things which are not clear to me.

1) The authors have used Asphalt Shingles and Felt Underlayment/SRAM for roof covering. However, the models shown in Fig 3 and Fig 5 do not show Asphalt Shingle layers in them. Were the two layers modeled separately or just in one?

2) They have mentioned the permeability of different components in PERM in Table 1. WUFI needs the permeability values in PERM-IN. Does it mean that we just have to multiply the permeability in PERM by the thickness of layer to get the effective permeability to be defined in WUFI model?

Thanks.

[Thomas]

1) The authors have used Asphalt Shingles and Felt Underlayment/SRAM for roof covering. However, the models shown in Fig 3 and Fig 5 do not show Asphalt Shingle layers in them. Were the two layers modeled separately or just in one?

Since this article doesn't seem to be publicly accessible I cannot comment on what they did. Maybe they combined the two materials into one layer, or maybe they modeled the outermost layer as a simple sd-value (in the "surface transfer coefficients" dialog).

2) They have mentioned the permeability of different components in PERM in Table 1. WUFI needs the permeability values in PERM-IN. Does it mean that we just have to multiply the permeability in PERM by the thickness of layer to get the effective permeability to be defined in WUFI model?

The permeance (measured in perm) is a property of a specific layer with a given thickness. The permeability (measured in perm inch) is a property of the material itself.
If you know the permeance and the thickness of a layer, you can compute the permeability of the layer material; just multiply the layer's permeance by the layer's thickness.

Regards,
Thomas