Guv Bob wrote:

What you have in this pictu

Different vent fan - was too noisy and vibrated off center- returned
http://i249.photobucket.com/albums/g...in/NOTUSED.gif

Is exactly what you see when you look under this "space ship":

Roof-top fan on a different house
http://i249.photobucket.com/albums/g...in/ROOFTOP.gif

I wouldn't install one of these again because of the windy rains we
get.

I have two of those on my roof. For one of them, I raised the "space
ship" top-hat by about 8 inches using 2x2 pieces of wood. I also
installed a taller screen to match the new height. The extra height
improves airflow. The wood struts are unequal length so the top-hat
sits level (with the ground - not with the roof). This keeps rain out
(yea, we get windy rain too sometimes).

Also I don't like cutting holes in the roof.

You want a ventilated roof, you're gonna have to cut holes in the roof.