Truss bearing at garage /house wall

[thorn]

Is it common practice to to have the trusses over the common garage /house wall "float" or bear (3 point truss) on this wall?

[Rich]

I don't quite understand your question. The situation depends on which direction the trusses run compared to the common wall - perpendicular or parallel.

[thorn]

Perpendicular would be the direction

[Rich]

Then yes - the trusses should bear on the common wall. One exception to this is if there is a bearing wall on the far side of the common wall that the trusses are extended out to.

[thorn]

Yes there is. A garge door header would be the other bearing bearing point.
How about trusses that extend out over a front porch area? Should they also extend & bear on the porch header, thereby "floating at he house wall, or bear on the wall between the porch and house and also the porch header?. Again, talking about perpendiular.
I guess my concern is how to deal with the air space created by the floatig truss, when it's between conditioned and non conditioned spce.

[Rich]

Typically the wall (in your case the common wall) will be framed up into the trusses and essentially treated as if it was an exterior wall. Another way is to make the exterior ceiling similar to an interior ceiling. Either way involves framing the exterior wall to the bottom side of the trusses.

[Don_P]

If I'm reading right, one way to do it is to sheath and side as Rich describes, then attach a trim to the trusses/ ceiling but not the wall, it would be able to slip. Drywall details I've seen for truss uplift call for screwing no closer than 12" to the wall, tape the seam ceiling to wall and it can bend if necessary rather than splitting the seam. The truss manufacturer should be able to give you bearing points, attachments and details.