Exterior Cladding, CanExel, Rigid insulation, R-value, Etc.

[Trepex]

Hi all! I’m back after a long hiatus! We’re building a new custom home in Ottawa, and it’s quite the different adventure from my previous tract builds.

Given the big increase in lumber costs since the onset of COVID-19, with our builder we seriously considered a complete switch to ICF for the above-ground floors. Our basement is already ICF. In the end we couldn’t justify the increased costs for two above-ground floors in ICF, including the engineering and architecture costs to revise plans, the delay going back to revise permits, etc. So we’re sticking with an ICF foundation and then traditional wood construction.

I’m wondering at this point though if there are some upgrades we can easily make to the cladding, from an energy efficiency perspective. We’re going with CanExel composite siding, and cladding will be standard OSB (not insulated panels). Our windows and doors have all been sized with a jam extension to account for the added thickness from the exterior strapping for the CanExel siding.

Is there an option at this point to still add some rigid foam extension on the exterior before the CanExel? I had already read a lot of mixed reviews about using insulated panels for cladding, where the foam is sandwiched between the exterior OSB and the studs. I get the advantages in terms of eliminating thermal bridging, but there seem to be other questions as to whether you really want the foam on the inside. I’m not even certain we could opt for that cladding at this point without it screwing up the depth of all of our windows and doors.

In any case, mainly looking at this from an energy efficient perspective and wondering whether it’s even worth these efforts at this point to try to increase the R-values of our walls beyond what will be around R-20 as it stands.

Thanks I’m advance for any ideas or advice and guidance!