A.Rachel Smith responds: The proper way to attach the bottom chord to the wall below depends on a few things. If the interior basement wall is load- bearing and the truss is using it as an intermediate support, the truss bottom chord must be directly attached to the wall, no matter what their relative orientations are. Check the truss design drawing from the truss manufacturer for information on the location and size of the required bearing points.
If the interior basement wall is non-load-bearing and perpendicular to the truss, you can leave a gap between the truss and the wall. However, for the sake of the wall's lateral stability, you may want to have some form of attachment, like a slotted metal anchor at the top of the partition wall, that will allow for vertical movement of the truss...
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