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Community and Q&A

getting rid of soffit vents on one side of the house.

cs55 | Posted in General Questions on

howdy, i live in the south and have a ventilated attic with a single powered fan. theres no hvac equipment in the attic and i recently installed baffles in every stud bay then spray foamed the entire top plate to completely air seal to hopefully prevent wind washing. very fun.  well, baffles for two sides of the house. 

theres around 230 feet of soffit in total and there are soffit vents every so many feet around the entirety of the home.

i was able to add baffles to every single stud bay along the green line, but the red lines are 110% inaccessible to install baffles. its a 10′ ceiling that is vaulted, and the soffits are only 8′ from the ground. not happening.

now if i were to remove/replace the soffits, i would have access to the top plates and i could spray foam them from that side, but i still couldn’t install baffles…

how important is that ventilation in reality?

i read this and it makes me feel like i would almost be okay if i blocked off the top plates with foam where the red lines are.

should i be concerned?

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  1. Expert Member
    BILL WICHERS | | #1

    I would prioritize the attic ventilation over the concern about wind washing of the insulation over the top plates. That basically means I'd leave the soffit vents in place and not worry about it.

    You may be able to install baffles from the soffit side. I've done this before. Use furring strips as the "ends" of the baffles, but cut them a bit long so that you can sort of cantilever them into the rafter bays. This lets you fasten them from the soffit area only, so that they self support up in the inaccessible area in the rafter bays. Use something lightweight for the baffle itself, such as thin 1/2" polyiso or 1/4" waferboard. TAPE it to the furring strips so that you have some play, and don't need a perfect fit. Tape and end piece on to fold down over the top plate. It's a bit cumbersome, but it works, and you can install it into the end of a rafter bay that would otherwise be inaccessible.


  2. Expert Member


    It might work and it might not. You will know in a couple of years whether moisture accumulation in those areas occurs or not. If you go ahead you should have a plan B thought out for what to do if you do have problems.

    1. cs55 | | #4


      so i have no hvac equipment in the attic. i did, but i swapped to minisplits. i went as far as even removing the ducts and ceiling registers then drywalled over where they were.

      i have spray foamed every joint and penetration that i can reach. the bathroom exhausts vent out the roof(surprisingly not common in the south)

      the attic is roughly r40 minimum, with r60+ everywhere i was able to make that possible.

      my 20 year old roof is finally being replaced this fall... i am getting some shingles from malarkey that are nearly white and have their highest solar reflection rating.

      theres effectively zero access to the top plates on that side of the house. it really sucks. so mitigation 2 years from now could be difficult

  3. cs55 | | #3

    thanks for the input!

    so what drove me to foam+baffle every bay is that when i got the house i noticed every single bay had wind washing to the extent that there was no insulation for about an entire foot from the edge of the top plate. if there was insulation then it was very little. basically a nice uniform canyon/crater around each stud bay top plate

    the only thing that the builder did for wind washing was some strips of felt paper or tar paper(i dont know what it was) stapled to the joists. despite that, there was enough wind to completely blow away insulation.

    so that was my thought process anyways...

    something else to make you shake your head;

    the builders didnt go through top plates for electrical. they went through the top of the sheathing because theres a 1.5" gap between the brick and sheathing as normal. dunno how normal that is, but thats another reason i am wanting to replace the soffits... gives me something else to airseal.

    1. Expert Member
      BILL WICHERS | | #5

      That's *extreme* wind washing if it actually moved the insulation out! Normally "wind washing" is just air currents blowing over and partially through the "end" of the insulation, reducing it's effective R value. I've never seen wind blow enough to actually clear insulation from an area, although I suppose it's possible. I would think it's maybe more likely that the original installers just didn't try very hard, and didn't get much insulation out into the more difficult to reach areas at the eaves, or they were trying to avoid blocking the soffit vents and were a little too conservative in their insulating in those areas because of that.

      If you have lots of oddball penetrations in those top plates, or next to them as it seems, spray foam is probably your best/only option to seal those areas up. You still want to try to keep vent channels in place though to avoid moisture issues.


      1. cs55 | | #7

        20 years of oklahoma winds i guess.

        i wish i took photos but each stud bay was a little different in regards to how the insulation looked. you could easily be right, though.

        some of the bays that had lesser insulation were way too uniform as if the same airflow was continuously going over an area. kind of resembled a bowl shape. some were missing that felt paper and those had much much less insulation.. practically bare.

        the rafters are 2x6 so theres a 5.5" gap for air flow with about a 20" overhang and larger vents. dont know how much that helps with air flow.

  4. walta100 | | #6

    It looks like you have a cathedral ceiling under a hipped roof if so, almost all of the sofit bays are blocked and useless for venting.

    For venting to be affective you need 45% of the vent at the ridge and it looks like you might have 6 feet of ridge and you can’t use the 18 inches on each end so you have almost zero high vent.

    The way I see it venting an attic is very important in a cold climate to prevent ice dams and moisture from accumulating over the long winter. My opinion is the amounts of air moved by venting an attic are so small any cooling affect in the summer is inconsequential.

    Note it is very likely the current power vent is depressurizing the attic and sucking conditioned air from your home and making your AC run more.

    Did you happen across this article


  5. cs55 | | #8

    When the roof is replaced i am thinking about going to passive vents.

    . part of the house has 8 foot ceilings, goes straight to 10' , then near the red line side of the house it has a 45ish degree curve to transition back to 8 feet along the exterior wall.

    the soffit bays along the green lines have a 5.5" opening on the top plate and a short drop to the soffit covering/vents. i dont know how good or bad that is for ventilation.

    but i cant even crawl to the red side to see how the opening looks.

    thank you for the other article, ill read that

    also, I don't knownif you're referring to a ridge vent. but i dont have a ridge vent. any twirly birds or 100% passive vents. just a powered fan.

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