Attic baffles question
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1. Should there be baffles in the corner of the attic? In the first image, it looks like there are open soffit vents there, but there are no baffles.
2. Are gaps at the bottom of the baffles where they meet the attic floor normal? Outside air is blowing through these gaps.
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In areas where there are hips or valleys, ventilation baffles are often not installed where the roof framing prevents ventilation from occurring. This also sometimes happens with gable roofs that have a drop-cord truss. Framing for the eave overhang will block ventilation and the baffles are typically not installed.
The gaps in the ventilation baffles that allow air to bypass the baffle will result in a phenomenon known as wind washing. The effects of wind washing
We typically use a closed cell spray foam to mitigate this issue when using a raised heal truss, but there are other options to air seal this area.
Randy
Thanks Randy. Can I use canned spray foam around the edges of the cardboard baffles to block any air from the soffits from escaping the channel? Or would be overkill as long as the largest gaps like in the photo are foamed?
I'd probably use a sealant over the canned foam where possible. The canned foam might be needed for slightly larger gaps. Any air that leaks into the insulation will degrade its performance, air sealing is good.
Yes, you can use spray foam to hit these gaps and the edges of the cardboard. It will close up the gaps and also help seal the cardboard to the framing. By eliminating the gaps you reduce wind washing.
As others have noted, you don't need to "air seal" the baffles. But you also want to reuce wind washing, and working in an attic is difficult. Like you, I've found hitting things with a can of spray foam is the simplest / easiest /quickest solution. It closes gaps, seals things, and adheres things, all with minimal precision needed. You can do it from an ackward position in the attic and get the job done. Is canned foam the least expensive or best environmental solution? Probably not, but for me I found it was the best.
Baffles don't need to be air sealed. Baffles serve two main purposes: the first is to help prevent wind washing at the edges of the insulation, the second is to help keep loose fill insulation from shifting out into the eaves and blocking the soffit vents. Neither of these purposes requires that the baffles be air sealed.
I'd probably patch over that large hole with some extra cardboard or some tape, but a few small gaps along the edges usually aren't a problem, especially if they're small enough that insulation won't fit through.
Bill