interior wood shear wall in multi-family housing

[jgajary]

I am designing a 3 story apartment building with 115mph wind loads and need to engage interior demising walls as shear walls. I am insisting these walls be structural panel sheathing. The architects are struggling with finding a UL rated 2x6 demising wall assembly that meets fire code and incorporates structural panel sheathing. Is this really all that uncommon? Does anyone know what architects usually do in this situation? It needs one hour fire rating.

 

[AELLC]

The 3 and 4 - story apt bldgs. I have done have all been relatively long and the lowest story int demising wall shear was usually 2 layers of gypbd, each side

 

[jeffhed]

jgajary,
I don't think its all that common. I have done plenty of townhomes and other buildings that require a 1 hour fire rating. The sheathing is nailed directly to the framed walls and then sheet rock on each side, not sure how many layers, it seems to me like it was only one layer. I know that the walls we used in the past were only 2x4 framing. The UL website is not very good as far as finding UL listings. The link below is to a wall type that an architect used on one of our past projects. I don't know if this can be used or not on your project, but it at least shows that it can be done.

http://database.ul.com/cgi-bin/XYV/...n=versionless&parent_id=1073984818&sequence=1

 

[jayrod12]

We do it all the time. granted the walls that we do it on get an additional layer of gyp added. So we put structural sheathing applied directly to the studs and then a layer of gyp is installed over this. We've done it for suite demising walls and stair wells. In fact the architects love doing it in stairwells as it improves the durability of the stairwell walls.

 

[msquared48]

The problem comes in the detailing of the intersections of designated fire/area separation walls and structural shear walls have to be discontinuous in places to allow the sheetrock to continue through.

Remember that structure is less important than fire requirements - similar to the green roof design philosophy.

Mike McCann
MMC Engineering