Designing Kitchens and Bathrooms - Bathroom Fan Vent

Anyone know a good site that shows how to install a bathroom fan vent? I am most interested in the penetration through the roof, how or if to transition to ABS, & if there are covers to keep bugs, etc. out.


Thanks,
abkent

Here is an illustration for a half-bath with a vent fan:
http://www.familyhandyman.com/200002/project/images/hb_figc.jpg
Basically, you need to match the size of the vent fan to the cubic footage of the bathroom (lengthXwidthXheight). Installation directions should come with it.
Same brand vent fans may look alike, but they come with different size cfm motors. You can't get one "too large", but you can get one too small.
Match the insulated duct to the size of the vent exhaust (usually 3"). The duct work must be insulated, not matter what you use, such as ABS, if running through an unheated attic to prevent condensation drip down through the fan.
The roof vent cover should have a spring-loaded flap to prevent insects getting back in when not blowing.
Good luck!
Mike