Garage 1st floor framing not aligned with 2nd floor trusses
We had a “pretty good” house built with an attached garage in Climate Zone 6A. The garage is 28’Wx36’D and shares a 22′ section of wall along the 36′ side.
The garage was designed/built using 2×6 construction on the 1st floor and trusses for the 2nd floor/roof. The 1st floor framing is 24″ OC as is the trusses albeit the trusses don’t line up with the 1st floor framing. They are about 8″ offset from each other. The local code enforcement officer questioned our designer on this and he was told they did all the calculations and it isn’t an issue.
The code enforcement officer made them install more 2×6’s on the 1st floor framing to align with the trusses above. They only did this on the free standing 36′ wall and they are only nailed at the top and bottom of their 10′ length. Since the siding was already on, they are not attached to the sheathing and I can easily move them side to side with my hand.
Is this an issue and are these additional framing members actually doing anything?
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Replies
If you have a double top plate the CEO is wrong
Put it this way, classic stud walls are 16 on center and trusses are frequently 24 on center
But CEO are never wrong so you probably should just forget about it
Absent a pic I don't understand the moving around thing
Keith, I appreciate the reply.
Yes, there is a double top plate.
"Absent a pic I don't understand the moving around thing"
Sorry, I wasn't clear. If I grab the 2x6 4-5' above the bottom, I can move it side to side fractions of an inch, which is how I know it isn't attached to the sheathing.
Hi Eric,
This is not going to be an easy question to answer with confidence without seeing a framing plan or some photos. As Keith said, aligning trusses with studs is an advanced, or value engineered framing technique that is about using less lumber more efficiently.
One of the things advanced framing with aligned trusses and studs allows you to do is have a single top plate. If you have double top plates, this alignment usually isn't necessary.
Perhaps the building official saw something else going on and asked for the additional framing for point loads, I don't know.
The fact that the additional studs can be moved around tells me that the builder didn't take the building official seriously and just added them to pass inspection. Whether they are actually needed or not, I can't say without more info.
To your question, are the extra studs doing anything. Based on your written description, My personal opinion is not much.
If you want to integrate them better into the wall, consider adding blocking in between the studs.
I'm not a structural engineer though. I'm just some guy on the internet. If you want to know for sure if it's required, you can look it up in your building code.
I agree. They are not necessary, but if they are staying the best way to make them add some structural value is to block them at mid-height.
If you have a set of engineered drawings, have the engineer that did the design seal (stamp) the drawings for the design with the non-aligned trusses and show that to the code people. Engineers can overrule code enforcement people.
That said, I can tell you that it isn’t always that easy. Sometimes the local code/building guys start doing the “not in MY city” thing, then you have to appeal to the state-level people. If showing the local guys sealed drawings doesn’t get their ok, you’ll need to decide if it’s worth the hassle, and potential project delays, that you’ll have to deal with to overrule the local building department people.
Bill
As others have said, as long as you have a double top plate the IRC does not require trusses and studs to be aligned. However, with large roof spans and heavy gravity loads it's not always a good idea to go with code-minimum. I had one project with a 44' truss span where an engineer said we had to add extra framing because the load on a double plate was too large for conventional practice.
The code reference for top plates is R603.3.2: https://codes.iccsafe.org/content/IRC2015?site_type=public/chapter-6-wall-construction#IRC2015_Pt03_Ch06_SecR602
Brian
I've attached more drawings from our home plans and a few pictures to show the added vertical studs on the first floor and the double top plate.
Thank you all for your responses.
I'm inclined to remove them to make more room for rockwool insulation.
Hi Eric.
Was there an architect or engineer involved? If so, I'd double check with them before removing the extra studs, however, I still can't see why they are necessary. And as others have pointed out, if you keep them, toenail them to the bottom plate and add some blocking.