Use manufacured and ca approved vents see below to retrofit existing attic soffit basement foundation and gable vents where possible.
Dryer vent through attic to soffit.
The international residential code allows you to run a dryer vent through the attic but you can t terminate it there.
This water vapor will condense on the cold lumber in the attic.
Soffit vents are intake vents so any air exhausted at that point will likely be sucked back up into the attic.
Instead fresh air still flows in through the soffit vents and travels along the underside of the sheathing until it reaches a ridge vent or can be vented with another type of exhaust vent.
Alternatively cover all existing vent openings with 1 8 inch or 1 16 inch wire mesh.
Avoid installing the dryer vent termination cap in a soffit overhang under a roof.
This also means that you can t blow the dryer exhaust into the attic or the crawlspace.
If an exhaust vent is too close to an intake some of that moist warm air is headed in to the attic.
Also the dryer and the bathroom fans should be vented separately and should never be vented out the soffit vent.
The vent cover still allows for proper maintenance and cleaning because of the box design and should prove to be more than difficult for rodents to gain access to the dryer venting.
The less back pressure is created by the roof vent the more efficiently the system performs.
Common 1 4 screens are ineffective and should be replaced or retrofitted.
And given the expectations for soffit venting and roof venting these days if an attic space is properly vented it would almost for sure preclude the soffit venting of any exhaust.
Air shall not be exhausted into an attic soffit ridge vent or crawl space.
Where the make and model of the clothes dryer to be installed is known and the manufacturer s installation instructions for the dryer are provided to the building official.
The duct serving.
I assume that your laundry is in an interior space and venting directly through an exterior wall is impossible.
Considering that back pressure higher than 6 wci is generally recognized as inefficient you can see that venting through the roof with non dryer specific vents is immediately problematic.
Range hoods shall discharge to the outdoors through a single wall duct.
You must terminate your dryer vent outside the building according to section m1502 of the irc.
The clouds of water vapor can easily find their way into the attic through soffit vents cracks or any other small opening.