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New 2024 Eave Baffle Code

E

Energystar

SAWHORSE
Joined
Aug 26, 2020
Messages
115
Location
Kansas
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"Where soffit venting is not continuous, baffles shall be installed continuously to prevent ventilation air in the eave soffit from bypassing the baffle."

One of the issues that arises with eave vents is wind blowing insulation. The new eave baffles attempt to remedy this. My question is whether or not the implementation shown in the following image would be acceptable as long a the ventilation area was sufficient.
1736789997171.png
 
Is the insulation stuffed in the bays prevents the wind from blowing in the attic insulation and lessening its R value? if not no.

2015 IECC R402.2.3 Eave Baffle

For air-permeable insulations in vented attics, a baffle shall be installed adjacent to soffit and eave vents. Baffles shall maintain an opening equal or greater than the size of the vent. The baffle shall extend over the top of the attic insulation. The baffle shall be permitted to be any solid material.

Think of vertical fiberglass in a knee wall, the back of the fiberglass is not designed to be exposited to wind currents.

You could check the manufactures installation instructions for details
 
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Is that fiberglass vertically above the plates and below the propervent? If so, negative. the fiberglass is not an air barrier. The whole point of wind wash baffles is to prevent cold outside air entering the soffit from flowing though the edge of the ceiling insulation (reducing its results value)

Anything like cardboard, 1/4" foam board in line with the exterior sheathing vertically above the plates with a gap or channel (depending on insulation thickness and CJ height) would get a pass..
 
Is the code only concerned about wind wash at the eaves? Is there really research that says wind wash doesn't impact the air permeable insulation not at eaves?
 
The baffle is to keep an air space between the insulation and the sheathing so that air can get from the eave into the attic and keep the sheathing cold to prevent ice dams. I've been using them since the 70s.
 
So with walls, its convection that's the issue along with an outside air barrier. For ceiling assemblys with a vented soffit its about not letting the outside air enter the edge of the fiberglass reducing its R value.. in the north east at least, plenty of ice gaming roofs were fixed by installing wind wash baffles.

Fiberglass R value works by trapping air. both issues above cause a significant enough drop in performance. Evidence of this is every old house with black stains on the fiberglass.

Now the center of a ceiling is left alone as there isn't enough height generally to cause convection...
 
Yankee Chronicler said:
The title of the thread implies that this is a new requirement in the 2024 IRC. How is this different from section 1102.2.3 in the 2021 IRC?
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So because the title says new, we know its not. That said it may be new to the OP.. its in table 402.bla.bla.bla (lol) in the 2018 IECC as well..

Most if not all of this goes back to 2007 and the Energy Star new home program and was included in the Thermal Bypass checklist which was required to be filled out by the Hers rater...

Yet, not a week goes by where I don't hear someone (who has been doing it this or that way for 20+ years) says its new...

Again for context many of the AHJ's in my area required Energy Star certification for CO on new houses. Yup, in 2007...
 
Does the blocking still allow you to use N1102.2.1 (R402.2.1) Ceilings with attics for reducing the amount of insulation? Doesn't seem the "...insulation extends over the wall top plate at the eaves..." to me.
 
mtlogcabin said:
Raised heel trusses is all we see here due to the R-48 insulation requirements.
Solid blocking required with the minimum 1" gap between the roof sheathing and solid blocking requirement

Raised-Heel Trusses - APA – The Engineered Wood Association

www.apawood.org www.apawood.org

View attachment 16260
Click to expand...

The downside to this detail is the vertical 2x sitting on top of the wall plate. The insulation is required to cover the full width of the top plates of the exterior walls. With this detail, it can't do that.
 
Yankee Chronicler said:
The insulation is required to cover the full width of the top plates of the exterior walls.
Click to expand...

I disagree

N1102.2.1
Where Section N1102.1.3 requires R-49 insulation in the ceiling or attic, installing R-38 insulation over 100 percent of the ceiling or attic area requiring insulation shall satisfy the requirement for R-49 insulation wherever the full height of uncompressed R-38 insulation extends over the wall top plate at the eaves. Where Section N1102.1.2 requires R-60 insulation in the ceiling or attic, installing R-49 over 100 percent of the ceiling or attic area requiring insulation shall satisfy the requirement for R-60 insulation wherever the full height of uncompressed R-49 insulation extends over the wall top plate at the eaves. This reduction shall not apply to the insulation and fenestration criteria in Section N1102.1.2 and the Total UA alternative in Section N1102.1.5.

N1102.2.3​

For air-permeable insulation in vented attics, a baffle shall be installed adjacent to soffit and eave vents. Baffles shall maintain a net free area opening equal to or greater than the size of the vent. The baffle shall extend over the top of the attic insulation. The baffle shall be permitted to be any solid material. The baffle shall be installed to the outer edge of the exterior wall top plate so as to provide maximum space for attic insulation coverage over the top plate. Where soffit venting is not continuous, baffles shall be installed continuously to prevent ventilation air in the eave soffit from bypassing the baffle.
 
mtlogcabin said:
I disagree

N1102.2.1
Where Section N1102.1.3 requires R-49 insulation in the ceiling or attic, installing R-38 insulation over 100 percent of the ceiling or attic area requiring insulation shall satisfy the requirement for R-49 insulation wherever the full height of uncompressed R-38 insulation extends over the wall top plate at the eaves. Where Section N1102.1.2 requires R-60 insulation in the ceiling or attic, installing R-49 over 100 percent of the ceiling or attic area requiring insulation shall satisfy the requirement for R-60 insulation wherever the full height of uncompressed R-49 insulation extends over the wall top plate at the eaves. This reduction shall not apply to the insulation and fenestration criteria in Section N1102.1.2 and the Total UA alternative in Section N1102.1.5.

N1102.2.3​

For air-permeable insulation in vented attics, a baffle shall be installed adjacent to soffit and eave vents. Baffles shall maintain a net free area opening equal to or greater than the size of the vent. The baffle shall extend over the top of the attic insulation. The baffle shall be permitted to be any solid material. The baffle shall be installed to the outer edge of the exterior wall top plate so as to provide maximum space for attic insulation coverage over the top plate. Where soffit venting is not continuous, baffles shall be installed continuously to prevent ventilation air in the eave soffit from bypassing the baffle.
Click to expand...

Yes, correct. Thanks for catching me over-simplifying.
 
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