I am building a 5100 s.f. home with SIP walls and a SIP roof. For reasons I won't go into here, we went with 12.75" panels for the roof (so that a 11 7/8" TJI can act as the spline). This was a late change to our plans so only now am I considering the design implications of this thick roof on the soffit and eave details. We have not placed the final order yet but will be doing so within 7-10 days.
This is not a "mountain home" or timberframe - if it were then the thick roof would look just fine with a square cut fascia and thick eave. It's more of a craftman style home with details you'd find on classic California bungalows. I'm concerned that the thick roof panels will not "fit" with the overall design of the house.
I know how to deal with this on the roof eaves. But its the rake on the gable sides of the roof that are problematic. I have not yet discussed this with the SIP mfg but here are some ideas I came up with...
1) On the panel that overhangs the gable end - the rake - instead of using one 12.75" thick panel, use two panels sandwiched together - maybe a 8" and a 4.75" panel. The 4.75" panel would be on the bottom and it would stop at the gable end (no overhand). The 8" pane would overhand the desired amount and would create an appropriately thick rake edge. The problem I see with this is in the spline connection with the next 12.75" panel (TJIs are used as splines).
2) Stop the 12.75" panel at the gable wall and then frame the overhang with dimensional lumber. This would require brackets to hold up the rake edge.
3) Work with the panel mfg to embed dimensional lumber in the panel that would stick out the appropriate amount to support the overhand rake edge.
I'm just curious if anyone has encountered a situation like this with a SIP roof where they chose not to extend the panels on the gable end for the overhang and they used some other method to create the rake edge.
Thanks,
Dave
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