CATIII horizontal vent over roofline

[bmwpowere36m3]

What are the clearances needed if terminating horizontally out a sidewall, but over a roof line?

I'm planning for an addition (leanto) off the back (gable end) of my garage. Ceiling height in garage is 14' and the addition will be 7' relative due to stepped foundation. Venting out the back wall horizantally seems to be the easiest option.

So venting horizontally over the leanto roof, what clearance above the roof line is needed? Based on Modine and Z-Vent manuals, the only clearances I can see are applicable are:

6-12" above snow grade
12" out from wall
Eave overhang <24"

So some like this:

 

[Jackfre]

MA is really a pitn on vent clearances. Or are you in CT? It helps to know. If this is being inspected have the product tech manuals in hand while discussing with inspectors. If not check on clearances with both the appliance manuf and the vent manuf. You will want to be above arbitrary "snow loads."

 

[bmwpowere36m3]

Located in CT and this won't be inspected. Not sure if it's more a snow blockage concern or problem with draft/poor chimney performance.