Roof baffles are foam ribbed panels which allow air flow between the top of the insulation and bottom of roof deck. They are typically manufactured to fit 16" or 24" rafter/truss spacing.
Placing roof baffles
Properly installed the bottom edge of the panel should extend past the outside face of the exterior wall framing into the framed overhang.
After properly placing the baffle, staple each baffle to the underside of the roof sheathing.
Testing for proper installation
When you are fully insulated you should be able to feel air escaping from the top of the baffle into the attic space.
If not you may have blocked the lower opening with insulation or you do not have adequate soffit ventilation.
Proper amount of ventilation
Soffit venting should be calculated at 1square foot of ventilation for every 350 square feet of attic for a balanced system.
- A balanced system has the equal amount of ventilation at the soffits as at the roof peak/attic.
- For an unbalanced system you are required to install 1 square foot of soffit venting for every 150 square feet of attic space.
For more information:
Read Jesse Terzi's Q&A "Should attic insulation extend into the eave soffits?"