For those of you that have built ICF to the rafters in a predominately home heating climate (Ottawa, ON. Canada) has anyone or would you recommend increasing the exterior foam thickness?

John

interested in this answer as well.

Ditto

You can increase the foam thickness if you want, and you will find a million opinions here. Bottom line is it will save you a few pennnies but some will tell you it's not worth the effort since it limits your choice in brands and may cause complications.

You can add EIFS (Exterior Insulation Finish Systems) on the outside, I believe upto 10" or 12". Your R-value will be significant. You will be limited to a stucco finish
a design analysis and structural analysis need to be done to determine your breakeven point for the optimal foam thickness in relation to your inside conditions (=temperatures)
After a certain thickness the more foam has no payback and is kind of "useless"

In Europe the foam is thicker on the outside, you can order it that way in Canada from a manufacturer.

To add to an existing build the final cost savings (Energy) vs. cost to purchase and apply product is a big separation, so I am led to believe.

Thanks for the replies!

John