I agree that you should NOT vent a dryer into an attic if it would even be up to code (which I doubt).
** In the new house I'm building... ***
Can't you design it so the laundry room is by an outside wall? During the building process, is the time to consider these things, if not before.
Going through the roof may be acceptable depending on the total length of vent, the material it is made from, how many elbows need to be installed and the dryer model you purchase.
You can read more about dryer vent considerations at the floowing link.
LINK > www.Appliance411.com
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