Timber Stud Wall Deflection Head Detail

[MHconc123]

Does anybody have a good deflection head detail for a timber stud wall?
It has been a while since I have done much domestic work and have a new timber stud wall being provided on an existing first floor timber joist layout. There is roof storage above and I want to ensure that the roof load does not transfer down the new timber stud wall into the first floor joists.
I am a bit conerned however that the cornice at the top of the new wall that would also be fixed to the existing ceiling may crack. i.e. the stud wall plasterboard would be fixed to the wall and the ceiling over could deflect slightly under the storage load.
Worst case I was going to stiffen up the floor below the new wall to take the load through the wall from the roof also. Ideally I would like to avoid this as obviously there is more cost and work on site required.
Am I perhaps being a bit overly cautious with regards to the cornice?

 

[msquared48]

Apparently, what you are erecting is a non-shear, non-bearing demising or partition wall. Just hold the top plate down 1/4" or so and use Simpson DTC clips or equal that allow the joists above to deflect without loading the wall.

No worries - check out the Simpson manual.

Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask

 

[MHconc123]

Thanks Mike.
My concern is actually probably more of the architectural detail.
I am just concerned that the cornice being fixed to both the ceiling and the wall will creat possible cracking as they deflect differently.
I may be overthinking this but ideally didn't want to have the cornice only fixed to the ceiling as I think it could look a bit odd with a 'line' visible from below. The cornice is a bit more ornate than the more simple profiles I am used to on residential projects where I know this detail is often adopted to allow for the defletion head at the top of metal stud frame walls.
Maybe I will ask a few architect contact whether they think it would be aesthetically ok to have it only fied to the ceiling.

 

[asixth]

How much are you expecting the floor joists to deflect with additional loading and would the ceiling plasterboard be able to tolerate some flex? For wood floor joists you should consider additional deflections with permanent loading due to creep.

 

[druminman]

Typically, the ceiling wallboard is not fastened to the floor or roof framing withing 18" of the partition and is fastened to blocking attached to the top of the partition. Simpson has detiails.

 

[keenaseng]

I have often called up vertically sliding ties to restrain the top of non-loadbearing walls, but I have never thought of the 'set' cornice joning locking the ceiling lining with wall lining... Often most of the load has been applied to the element above before the cornice is set (ie. deflection has already occured), so maybe why havent had too many issues in the past. But if you are expecting load to be variable after the cornice is set, which I think storage is, I think you are right to consider it.