Wood Shear Wall to Meet 2012 Energy Code

[cfox142]

I am starting to get more projects that are under the 2012 Energy Code. Normally I don't bother with this and let the Architect figure it out but with the new code it seems there is a clause to have continuous insulation. From what I have been told this means that the insulation between the wood studs is no longer adequate. The Architect is claiming we have to have 5" of rigid foam insulation on the exterior of the building. So I will have 5+" long screws with washers to hold the insulation to my wood sheathing but then I do not have any way to attach the siding unless I again have 5+" screws through the siding and insulation. Is anyone else running into this? How is everyone meeting the continuous insulation requirements for wood framed structures? Is the Architect forgetting to mention an exception for this?

Thanks,

 

[XR250]

Mine never have more than 1 1/2" of foam. They usually attach furring strips thru the foam into the studs and attach the siding to that. For lap siding, the furring strips bear on the foundation to prevent prying of the screws. For vertical siding, the siding bears on a treated member on the foundation for support.

 

[jayrod12]

I've been told something similar to XR250, they just need a thermal break at the studs. Therefore still provide the batt insulation between the studs for the majority of the insulation value, then add 1 1/2" of rigid to the outside.

 

[cfox142]

Anyone using the ZIP panel system?

 

[concretemasonry]

cfox -

It seems your are at the mercy of the architect now unless you cn come up with an alternate solution. Wood is recognized to be a "thermal short-circuit".

There is an alternate method that eliminates the short circuit by using 2x4 studs for a 6" thick wall that allows for flexibility (and lesser thickness of exterior foam.

The wall is on a 2x6 plate with two layers (inner and outer face) of 2x4s offset by half of the spacing so there is NO direct heat path. This allows batt insulation (better than nothing) to be placed horizontally, woven between the alternating studs. In some cases, the studs can be spaced at 24" o.c. if the longitudinal shear loads are not great and the vertical wall strength is improved.

Dick

Engineer and international traveler interested in construction techniques, problems and proper design.