Metal Hardy Panels and Thermal Bridging
Our structural engineer has introduced two ‘hardy panels’ into the ground (1st) floor north facing wall in our remodel for structural (primarily sheer) strength as we have a lot of window/patio doors in that plane.
The wall assembly was already somewhat challenged from an overall (assembly R-value) perspective given the glazing and while the house is 2×4 framed we had decided to replace this wall with a 2×6 to allow us to update the insulation in the non glazed areas. It seems to me that the hardy panels will somewhat / considerably reduce the value of our planned full cavity depth Rockwool. We’re not able to accommodate external insulation on this wall, and so….
I’m wondering if anyone has any smart ideas for mitigating the impact of what I expect (I haven’t modeled) will be very significant thermal bridging (both through the wall, and into adjacent dimensional lumbar framing members) that the panels will introduce.
Current plans have us sheath the building with ply; and WRB is Henry BlueSkin. We are paying attention to air sealing, and will aerobarrier the building pre-drywall. The current plan is 5/8” drywall to the interior.
We’re very lucky to be in an extremely moderate climate (Over the course of the year, the temperature typically varies from 44°F to 74°F and is rarely below 38°F or above 84°F).
Thanks in advance!
GBA Detail Library
A collection of one thousand construction details organized by climate and house part
Replies
I'm not sure what you mean by "Hardy panels." It sounds like they might be moment frames? Can you share any drawings or additional details?
Sometimes if you make it clear to structural engineers that you don't want to use steel framing, they can find a way to make it work with engineered wood and metal connectors. Other times it has to be steel. That's one risk of designing a home with a high percentage of glazing; there may not be enough wall left for lateral support.
Edit to add: it looks like you're talking about this shear panel system: https://www.hardyframe.com/shear-wall/. If you don't have enough unglazed wall area for the code-required wall bracing, you may not have other options.
mark_gill,
See if you can switch to Simpson Strong-Tie shear panels, which are wood based.
https://www.strongtie.com/products/lateral-systems/strong-wall-shearwalls/technical-notes/insulating-steel-strong-wall-panel-faq
Hi,
Add exterior insulation over the metal Hardy frames. Make up some architectural element or detail that add thickness to the outside of the wall to hide the exterior insulation extra thickness.
Thanks; we’ve managed to get 2” to the outside and 2” to the interior of the panels and so plan to add rigid foam either side which will hopefully help manage.
I looked at the Simpson Strong Tie product, which looks great but unfortunately didn’t meet the engineering requirement for this wall. It does work between our garage doors though - good pointer thanks!
Thank-you! Yes, the Hardy Panels are steel sheer wall components, and unfortunately it turned out that our engineer had considered the Simpson Strong-Tie product, which looks really good - but didn't quite meet the performance characteristics he needed given the amount of glass in the rest of the wall.
The engineer has however been able to reduce the thickness of the panels to 3.8", and so we will be able to add R6+ outboard, and R6+ inboard from the panel which we hope will materially reduce the thermal bridging.
mark_gil,
The panels are also C-shaped, so you will have some cavity insulation as well.
Thank-you, yes. I'm not sure what value i'll get from filling the void with insulation given as you note the 'C' shape which creates continuity from the outside to a c. 4" vertical flange each side to the interior; but will certainly be filling them with insulation!.