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vented and unvented soffit – where/when are each used?

rlangley | Posted in General Questions on

I am finding conflicting advice on when/where to use vented soffit vs unvented soffit.  There are four locations/situations that I am hoping for direction.  House eave (I believe this is where vented would be used in combination with a ridge vent), House Rake (unvented?)  Unheated garage connected by a covered walkway to the house – eave (vented or unvented?)  rake (vented or unvented).
Location – Ontario Canada.  rakes on house face East West, Garage rakes face North – south side faces house.  Hope this is enough info.
Thanks in advance.

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  1. Expert Member


    The general rule of thumb is you vent the soffits which will be part of your roof ventilation - so where they connect with a vent space on top of rafters, or an attic. There are climates where venting all soffits may help disperse moisture, but Ontario isn't one of them.

    So taking your examples:
    - Eaves on both the house and garage get vented.
    - Rakes anywhere would only be vented in special circumstances - that is to allow air to get into the first rafter bay, if framing blocked that bay from being vented vertically as the others were.

    1. rlangley | | #2

      Thanks Malcolm...much appreciated. Out of curiosity how critical is it to not vent the rakes? The house and garage have new steel roofs installed over 1x4 strapping over 1/2" plywood. I am in the process of building the house and am aiming for less than 1 ach@50.

      1. Expert Member
        MALCOLM TAYLOR | | #3


        Not at all critical. The main reason not to is just the additional work that might be involved. Most production builders use the same perforated soffit material everywhere, and don't distinguish whether something needs venting or not.

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