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Can I install 1/4-inch fan-fold board instead of rafter vent chutes?

onlyhenoswhy | Posted in Energy Efficiency and Durability on

I live in ohio. zone 5, and was thinking to add blown in insulation to my attic to bring the r value to r39. right now I have existing fiberglass insulation with some blown insulation on top. It’s has partly wood down for some storage which I plan to build the outside up to hold the blown insulation off the walk way. Question I have is I have to install rafter vent chutes from the eve to stop the insulation going into the eve. I was wondering if I buy 1/4in fan fold board which comes in 50ftx4ft . It would be cheaper and easier to install than buying rafter vent chutes and install them to each rafter bay on the sheathing. I was hoping to just nail the fan fold to the under side of the rafter from the eve up the length of the board which would create a vent chute that insulation couldn’t get into the eve

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  1. GBA Editor
    Martin Holladay | | #1

    You probably don't need the full rafter depth for these ventilation channels. Generally, it's wise to aim for 2-inch-deep channels.

    Fan-fold is a little flimsy for this purpose; most people use stiffer material.

    Here is a link to an article that discusses all your options in detail: Site-Built Ventilation Baffles for Roofs.

  2. onlyhenoswhy | | #2

    Thank you martin.

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