Snow problem in isolated slanting roof

[Mehmet Akman]

I would like to know what is the best solution to prevent snow (and of course snow dust) which can come from the soffit or ridge and stay on the insulation layer, in an isolated slanting roof, with 3-4 inch high air gap between roof deck and the insulation.

[Fred Weck]

The Minnesota Energy Code calls it a rigid wind wash barrier. The wall sheathing is extended up between the trusses or rafters to the underside of the ventilation baffles/chutes. This is usually accomplished by cutting pieces of sheathing to fit between the trusses or rafters. There are also baffles that are made to bend down at the outside edge of the wall to accomplish the same thing. Those baffles need to be water resistant, they are usually plastic or "waxed" cardboard.

[Mehmet Akman]

The Minnesota Energy Code calls it a rigid wind wash barrier. The wall sheathing is extended up between the trusses or rafters to the underside of the ventilation baffles/chutes. This is usually accomplished by cutting pieces of sheathing to fit between the trusses or rafters. There are also baffles that are made to bend down at the outside edge of the wall to accomplish the same thing. Those baffles need to be water resistant, they are usually plastic or "waxed" cardboard.

Thanks Fred,

I also think of using baffles and close the opening, but i afraid for not having enough ventilation, which may cause ice damping

[Fred Weck]

Mehmet,
The baffles / chutes extend about 3 feet into the attic space, about a 1-1/2 down from the sheathing. It will need to be a really hard wind to blow snow into the attic, but the ventilation is still there.