Venting is what prevents ice dams. It's more important the more cold and snowy your climate is.

I actually came to a different conclusion than Don for where I live (lots of snow, very cold). Snow piles so deeply here that the ridge wont properly vent when it's most needed.

The code wants you to balance the area of the soffit vent with the area of the ridge vent. Don's warning about gable vents is that if they aren't big enough not enough air will be drawn through the soffits. Joe Lstiburek, the best building scientist of this generation, suggests that you want less gable/ridge venting than soffit because you do not want to depressurize the attic, which will suck hot moisture laden air into the eaves potentially causing condensation/mold/rot.

I think a continuous soffit vent, and then vent channels in rafter bays that extend to above the collar ties with gable vents would work fine. Air sealing, especially at the eaves, is extremely important, and the more R-value you can get at the location the better as well.

Now that I'm on the subject of windows it may also be useful to add in some sort of window well feature:



Window Well Options:

Type: Steel
Shape: Rectangle, Arc, Trapezoid
Width:
Projection:
Depth:
Radius:
Vertical Offset:

Version 1.7.7 - 09.18.2021
- Added an ICF option for stemwall steps.

I've been giving the "wall sandwich" thing some serious thought the last couple of days and I think I can implement a workable system however it will drastically change the way I am currently doing things as well as break any sort of backwards compatibility with previous versions of the plugin and their models.

In the global settings I will probably have a select number of options you can choose from to build your custom wall sandwich (I will also have some standard ones pre-defined).  Interior and Exterior walls will be different in that you cannot use wainscot and cladding with interior walls.  Interior walls can be asymmetric with this new system so you can have different layers specified on each sides of the wall, unlike the current system which limits interior walls to symmetric configurations only.

Exterior Walls:

Ext. Side:

- Wainscot
- Cladding 1
- Cladding 2
- Airgap 1, 2, 3 etc...
- Sheathing 1
- Sheathing 2
- Insul 1

Int. Side:

- Gypsum 1
- Gypsum 2
- Gypsum 3
- Airgap 1,2, 3 etc...
- Sheathing 1
- Sheathing 2
- Insul 1

Interior Walls:

Ext. Side:

- Gypsum 1
- Gypsum 2
- Gypsum 3
- Airgap 1,2, 3 etc...
- Sheathing 1
- Sheathing 2
- Insul 1

Int. Side:

- Gypsum 1
- Gypsum 2
- Gypsum 3
- Airgap 1,2, 3 etc...
- Sheathing 1
- Sheathing 2
- Insul 1

The actual layering can be in any order except for wainscot which will always be the outermost layer on an ext. wall.  I'm not sure that two layers of cladding are really needed for an ext. wall but I'm just throwing it out there for now and see what sticks.

As far as the framing/wall solid is concerned I only plan on having one layer for framing, if I were to change that up to a variable number of framing layers things would get very complicated with regards to corner configurations so it is best to not get too ambitious.

The items shown are all of the possible layers for each side of the wall in question, one could theoretically enable all of them or none of them, and the number of air gaps is probably not limited.

Am I missing anything?  Thoughts? 

Your feedback now is important, once I install/implement a new wall sandwich system it will be more difficult to fundamentally change it from the form it originally takes.

Version 1.7.6 - 09.14.2021
- Added an ICF option for polyline stemwalls.
- Added an ICF layer in the Global Settings under the "Layers" tab.
- Fixed a critical bug with custom materials that was caused by the change in the location of the plugin's data sub-folder.





View model here:

https://3dwarehouse.sketchup.com/model/0a683d20-7115-491b-afc6-3578f584c5ae/ICF-Stemwall-Foundation