Soffit vents & Attic Baffles & Insulation question

2 years ago

last modified: 2 years ago

My eves have 15" overhang and contain soffit vents, the attic is blown insulation and I just finished expanded the vents holes and cleaning out the eves of blocking insulation where the soffits were. It was easy to get the insulation out of the eve from the outside of the house but is difficult to access while in the attic.

I'm in the process of putting attic baffles up in the attic where the soffit vents are, some vents span 2 rafters so I've cleared out both sides and putting baffles up on each side.

My question is, is it OK to leave the other areas that have no soffit vents full of insulation? I might be able to access about 75% of the eves to clear them out from the attic but not sure it's necessary or beneficial, can't seem to find any info that clarifies. I have about 5 soffits on each side of the house, the house is gable style and the overhang/eve runs around the perimeter of the house. I will blow in more insulation when I'm done with the baffles and putting up a radiant barrier.

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Charles Ross Homes

2 years ago

Hi, HU,

The purpose of insulation baffles in an attic is to maintain an open path for air flow from the soffit vents to either the hip and/or ridge vent. If there's no soffit vent, there is no potential for air flow and no need for a baffle.

The efficacy of gable end vents is debatable. The fact that they admit wind-driven rain and snow makes them something to avoid, in my opinion. We install them in gables when needed for aesthetics, but we don't cut a hole in the wall sheathing so they don't allow air flow into the attic. I also recommend against powered attic vents--they depressurize an attic and draw conditioned air from the living area which is replaced in summer by warm, potentially moist, air.

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Comments (7)

klem1
2 years ago
Depends on size of vents and rafter bays Twice sq inches opening between top plate and deck as vent opening is sufficient. Extra space required due to turbulence resistance as flow direction changes as it passes to attic. You roof style sounds like hip rather than gable. Gable vents in gable roof work but hip requires ridge vent,power vent or something. That is to say without an escape route sofit vents loose much of their benefit. No where near as good as you are doing but lazy owners can clear some insulation by directing leaf blower into vents ever year or two.
HU-670818602 thanked klem1
HU-670818602
Original Author
2 years ago
last modified: 2 years ago
You are correct and it is a hip style not gable - did not realize the difference until I just looked it up. There are two wind turbines on the 2nd floor roof to vent the hot air - it's a 1 1/2 story home where the attic is open to the 2nd floor roof on 3 sides.

I've now got good airflow from the soffits to the roof but was not real sure if I need to clean out the rest of the insulation in eve/overhang/channel. There are approx. 20 raffters on each side, say in between 5 of them there is a soffit vent which is now clear of insulation. I'm just wondering now if I should spend the time and effort to clear out the spaces that don't a soffit vent underneath, is it designed for air to flow through the entire overhang or just from the soffit vent up in to the attic? Hope that makes sense.

This picture shows the types of venting Have, 23 soffit vents around the house.
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cat_ky
2 years ago
I have a one story hip roof house, and I have several vents on the front and back, and 2 on each side. I have 3 turbines on my roof, and there are 4 of the roof vents on the back side of the roof also.
HU-670818602
Original Author
2 years ago
Thanks everyone, based on Charles recommendation I will continue to baffle between rafters that have the vent to maintain the airflow and for those rafters that have no vent will just leave the blown insulation in place.
aklogcabin
2 years ago
I believe that you are on the right track with the plan that you have
HU-670818602 thanked aklogcabin
HU-670818602
Original Author
2 years ago
Thanks aklogcain, good to hear. Anywhere the vents spanned two rafters I baffled and cleared out both. Everyone's comments were helpful and timely - I asked a new question about the best way to insulate above the bay window if anyone has comments also appreciated.

https://www.houzz.com/discussions/6416454/insulating-bay-window-extending-out-of-exterior-wall