I am planning on installing a whole house fan (shown in the image below). The fan has a total system weight of 40 pounds and needs to be supported via metal and nylon straps to a beam as shown in the image below.
My roof does not have these cross beams. I am thinking about attaching a beam (2x4) via 10 penny nails as shown in the drawing below:
My question is is there anything wrong with this approach? Could the load cause the roof to sag or any other problems I'm not thinking of?