Yes, the combination of soffit and ridge vent encourages air flow in the directions wanted, helping to move warm moist air out of the coop. If you expect heavy snow falls, and are unable to clean the roof of snow frequently, that CAN be a problem for ridge venting. In mitigation, you can offer gable vents (though these tend to disrupt the operation of the soffit vents in better weather), steepen the roof angle to better shed snow, and consider a monitor roof design. Really, only the monitor roof or a half monitor roof are suited for particularly bad snow falls when you can't get out there for manual snow removal.
Framing either is about equal difficulty, but if you have a strongly prevalent wind direction (say, it always comes off the lake in winter), you can set your roof line perpendicular to it, so there is less tendency of windblown snows to be pushed or packed. 3/12 is the minimum pitch any roofing material mfg will recommend for shedding water, I would definitely go steeper if heavy snow loads are expected, in hopes some will shed on its own, as long as you can still safely clear it. 5/12. at 7/12, its more high than wide, and will shed very well, but may be wasteful of materials, and its very difficult to walk on or work on.
Not a fan of low (near floor board) ventilation unless you have a way to keep it off the birds.
Sure, I use it myself, in that my coop sits 3' off the ground, allowing cool, shaded air underneath it (I live in FL and have to deal with heat, not snow) - but my hen house has a central shaft that allows that air to rise up thru the center of the house, while the birds roost in a sheltered "U" shaped space around it. That's not a practical design for most chicken keepers.
In any event, ridge and eave vents probably don't provide enough free ventilation space to meet the needs of your chickens, even with gable vents at either end. If your eave vents are open (but for hardware cloth) and based on 2x4 framing on edge, you are only gaining 1/3 sq ft of ventilation per linear foot - and even that's effectiveness is limited by the much smaller volume air allowed to pass under the ridge vent. If you previously did home attic ventilation, I'm sure you know about balanced passive air flow design.
So, you will need some number of windows, or some form of monitor roof, rather than ridge venting, for optimum air exchange.
Framing either is about equal difficulty, but if you have a strongly prevalent wind direction (say, it always comes off the lake in winter), you can set your roof line perpendicular to it, so there is less tendency of windblown snows to be pushed or packed. 3/12 is the minimum pitch any roofing material mfg will recommend for shedding water, I would definitely go steeper if heavy snow loads are expected, in hopes some will shed on its own, as long as you can still safely clear it. 5/12. at 7/12, its more high than wide, and will shed very well, but may be wasteful of materials, and its very difficult to walk on or work on.
Not a fan of low (near floor board) ventilation unless you have a way to keep it off the birds.
Sure, I use it myself, in that my coop sits 3' off the ground, allowing cool, shaded air underneath it (I live in FL and have to deal with heat, not snow) - but my hen house has a central shaft that allows that air to rise up thru the center of the house, while the birds roost in a sheltered "U" shaped space around it. That's not a practical design for most chicken keepers.
In any event, ridge and eave vents probably don't provide enough free ventilation space to meet the needs of your chickens, even with gable vents at either end. If your eave vents are open (but for hardware cloth) and based on 2x4 framing on edge, you are only gaining 1/3 sq ft of ventilation per linear foot - and even that's effectiveness is limited by the much smaller volume air allowed to pass under the ridge vent. If you previously did home attic ventilation, I'm sure you know about balanced passive air flow design.
So, you will need some number of windows, or some form of monitor roof, rather than ridge venting, for optimum air exchange.
