Shearwall...clarification... 4

[Mountainrunner]

Question...

I know a shear wall transfer loads from the roof....but....could a shear wall stop at the floor of an uninhabited / non storage attic and still be considered / designed as shear wall....could the attic joist sitting on top of wall be used as collectors transfer loads from the roof...(attic joists are nailed to rafters)..

Could this be done?....

I ask because my client wants to remove a wall and existing drawings call the wall a SW...but...wall stops at attic...it does not go to the roof...

May be there is a provision in which the shear wall could stop at the attic and still be used as sw....using the attic floor joists as dragging collectors..I attached 2 pics....one picture of the attic...the king post rest on the wall to remove....and a sketch of the condition...

To me such condition is just a bearing wall not a shear wall....

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any advice....thks

 

[r13]

It looks like the short post is supported on the 2-2x8, does the 2x8s adequate? Is there a similar wall on the opposite end?

 

[phamENG]

The effectiveness of that shear wall does seem questionable. However - gypsum wall board has been allowed as a diaphragm sheathing in the past. It might be "okay" now - not sure, but I wouldn't do it anyway as I have some serious concerns over its long term durability. It could be that the ceiling was considered the transfer diaphragm. Check out section 4.9 in this Evaluation Report.

Either way, I think you should investigate the lateral load paths in this house. If the drawings say it's a shear wall, and you say it's okay to remove it, you now own the lateral load resistance capabilities of the structure.

 

[AaronMcD]

You can transfer roof loads through rafters into attic joists and into shear wall. You could look at the edge connection and see if it has any special connectors. A few nails probably won't cut it.

If the existing plans call it a shear wall, I'd keep it there or replace with equal or better.

It should be easy enough to look at the house as a whole and see if it needs a shear wall there. If it needs a shear wall it's likely a shear wall. If it doesn't need a shear wall, well, it's still a shear wall originally, so you can only remove it if you have done a full analysis and determined it's all good. And as phamENG says, you now own it.

http://www.hellodwell.design

 

[KootK]

Was the specifier of the nebulous shear wall a fool... or a genius? It's hard to tell.

1) As it's set up, I don't think that wall is a shear wall in the conventional, wind/seismic sense of the term. It's just too close to a nearby perimeter shear wall which is sure to be more robust in terms of both its own construction and its connections to the diaphragm.

2) I wonder if the wall is in fact a shear wall, just not one designed for shear ostensibly. Rather, the shear wall is meant to laterally stabilize the post above in which case removal of the wall in favor of a continuous, full height post would be altogether doable.

This is very much speculation on my part rather than certainty. Put me down at a confidence level of, say, 53%. You'd sorta think that the same thing could have been accomplished by just running the 2-2x8 out to the rafters and dumping the thrust there. Of course, then, an owner might tank his structure by removing that joist or it's connection to the rafters in the future which, of course, lands us right back where we're at now, having a cue that something might be amiss with the wall removal.