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Sheathing vs Shear Wall
- Thread starter Mar A
- Start date
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Shear wall is an assembly that includes the foundation, framing and sheathing. Sheathing refers to a myriad of things from Celotex to plywood and more.
A plans examiner with this question would be well advised to talk to an engineer employed by the building department and should limit his efforts to the most basic sort of permits.
From an engineer's perspective the sheathing that is a part of a shear wall and consists of either plywood or OSB.
The existence of sheathing does not automatically make a wall a shear wall.
The basic concern is that the building needs to resist the horizontal loads resulting from significant wind or rom an earthquake. To be effective there must be a load path that allows the forces to be transferred to the foundation. The framing and hardware must allow the shear wall to resist overturning forces. If not the shear wall will tilt over.
While the IRC provides prescriptive provisions that address these situations for a limited set of buildings in general the determination of whether there is sufficient lateral resistance needs the knowledge of a professional engineer.
From an engineer's perspective the sheathing that is a part of a shear wall and consists of either plywood or OSB.
The existence of sheathing does not automatically make a wall a shear wall.
The basic concern is that the building needs to resist the horizontal loads resulting from significant wind or rom an earthquake. To be effective there must be a load path that allows the forces to be transferred to the foundation. The framing and hardware must allow the shear wall to resist overturning forces. If not the shear wall will tilt over.
While the IRC provides prescriptive provisions that address these situations for a limited set of buildings in general the determination of whether there is sufficient lateral resistance needs the knowledge of a professional engineer.
redeyedfly
REGISTERED
You can also have gypsum sheathed shear walls.
Snarky as ever. Why can't you be nice to the people that come here for advice. Mario started out with, "Entry level plans examiner here." and you just couldn't keep your big mouth shut.
Mario,
There was a day when the blowhard was not an engineer. He didn't know a shear wall from a shitter wall. Well he does now. He thinks that he's a big fish in a little pond. Tigers don't like fish....too boney.
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steveray
SAWHORSE
Sheathing may resist shear forces...but it may not.....I believe Simpson Strong Tie has some good online classes or maybe even in person....Only a mild plug as I have learned a bunch from our northeast folks....
Gypsum sheathing has very limited values and is seldom used by engineers. In addition when subject to earthquakes the nails crush the gypboard causing the lateral capacity of the gypsum panels to degrade very quickly.
A plans examiner should know his or her limits.
A plans examiner should know his or her limits.
As well as you should too. It's not up to you to spank plans examiners.
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bill1952
SAWHORSE
Mario - Is this an IRC building? I assumed so but discussion made me wonder.
redeyedfly
REGISTERED
You might want to dust off your SDPWS. Gyp sheathing has less capacity than plywood but not that much less. Also, you're typically counting both sides of a gyp shear wall unlike wood panels where you're often asymmetrical and cannot. Gyp shear walls are used all the time in wind country, often as you get to higher floors.
Granted, if you need high numbers you can't reduce edge nailing spacing to get more capacity out of gyp like you can with wood panels.
Mario, go to the apawood.org and look for their free webinars on Braced Wall Panels - they will teach you a lot. APA stands for the American Plywood Association, they changed their name to "The Engineered Wood Association" but they still go by APA.
They also have a Youtube channel, but you can get CEU credits if you watch on their website.
I would note that the term "shear-wall" is not used prescriptively in the IRC. In the IRC it is defined as:
"[RB] SHEAR WALL. A general term for walls that are designed and constructed to resist racking from seismic and wind by use of masonry, concrete, cold-formed steel or wood framing in accordance with Chapter 6 of this code and the associated limitations in Section R301.2 of this code."
If something is being designed prescriptively through the IRC then it will be per R602.10 "Wall bracing" and it should be called a "Braced Wall Panel." If plans call it a "shear wall" then it should be an engineered design and should be accompanied by stamped calculations.
The IBC definition is:
"[BS] SHEAR WALL (for Chapter 23). A wall designed to resist lateral forces parallel to the plane of a wall.
Shear wall, perforated. A wood structural panel sheathed wall with openings, that has not been specifically designed and detailed for force transfer around openings.
Shear wall segment, perforated. A section of shear wall with full-height sheathing that meets the height-to-width ratio limits of Section 4.3.4 of AWC SDPWS."
"[RB] SHEAR WALL. A general term for walls that are designed and constructed to resist racking from seismic and wind by use of masonry, concrete, cold-formed steel or wood framing in accordance with Chapter 6 of this code and the associated limitations in Section R301.2 of this code."
If something is being designed prescriptively through the IRC then it will be per R602.10 "Wall bracing" and it should be called a "Braced Wall Panel." If plans call it a "shear wall" then it should be an engineered design and should be accompanied by stamped calculations.
The IBC definition is:
"[BS] SHEAR WALL (for Chapter 23). A wall designed to resist lateral forces parallel to the plane of a wall.
Shear wall, perforated. A wood structural panel sheathed wall with openings, that has not been specifically designed and detailed for force transfer around openings.
Shear wall segment, perforated. A section of shear wall with full-height sheathing that meets the height-to-width ratio limits of Section 4.3.4 of AWC SDPWS."
I don't know man, I think his answer was pretty good, and taken at face value I didn't see anything that was rude or not "nice."
I guess that first statement could be considered snarky, but he's not wrong. Maybe it could be "nicer" if he said "An entry level plans examiner..." and "and the supervisor should limit..."
I think you two need need some boxing gloves and a ring. <said with snark and sarcasm> The rest of us can grab some beer or popcorn and enjoy the show! I know I'm newer here and there's probably some history but I will say it's definitely entertaining! And educational, I've learned a lot from both of your posts.
tmurray
SAWHORSE
Great question from a new plans examiner to make sure you are doing your job properly and some great responses here in this thread to help you out. Welcome to the forum and the industry!
redeyedfly
REGISTERED
Maybe except the part where it's seldom used by engineers. If I see wood structural panel shear walls on the top floor of a III or V I know the engineer is being lazy.
Please excuse me.
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ADAguy
REGISTERED
Listen to him, are you ICC certified yet? Buy Ching's books for graphic clarifications .
north star
MODERATOR
- Joined
- Oct 19, 2009
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# # # #
All, ...we want to encourage people like MarioA to come
to this Forum and learn, share and find assistance, and
NOT be put off by asking basic questions.
We want MarioA to go and tell others that there is "positive"
place on the internet to go and ask Code related questions.
If you noticed, he hasn't asked any more questions.
Ya'll play nice & BE nice to our visitors, and regular Forum
members.
# # # #
All, ...we want to encourage people like MarioA to come
to this Forum and learn, share and find assistance, and
NOT be put off by asking basic questions.
We want MarioA to go and tell others that there is "positive"
place on the internet to go and ask Code related questions.
If you noticed, he hasn't asked any more questions.
Ya'll play nice & BE nice to our visitors, and regular Forum
members.
# # # #
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I guess I am to assume that ICC certification trumps being a licensed engineer with considerable experience with residential structures. My mistake.
tmurray
SAWHORSE
Good advice. I still reference handbooks for the odd thing today.
jar546
CBO
Gypsum is used as part of a shear wall frequently in areas of the country outside of earthquake zones. There are specific nailing patterns called out by the licensed architects or engineers that design them. Sometimes we need to step outside of the little bubble we live in and realize that there are both round holes and square holes in this world. The world's axis does not rotate around the area we live in.
Genduct
REGISTERED
Mark, it seems what you are saying is "being a Professional Engineer" trumps the ICC Certs. Many of us have spent the first part of our work-life trying to build what Some Puppy Engineer thought was a good idea! Remember what it was like Before you gained some real experience. Just like the new guy who asked that basic question
Many of us transitioned to Bldg Code Officials as a second career and brought that real-life experience to the table.
Seems like we should all just understand who we are speaking with ( not to and certainly not at) and then we can figure out how we can take advantage of what the other knows and hence do a better job
Personally, I had 45 years of Commercial Building and Mechanical Construction experience BEFORE I applied for the job. , For me, it was the icing on the cake since those Code choices were made before I got the plans. For me it was a way to deal with the boredom of not working job site.
I would be happy to compare notes with you and you can figure out if your PE Status makes me less informed than you
A little humility might be something we can all strive for, Me Thinks
If the ICC certificate is in the possession of a duly sworn plan checker then your assumption is entirely correct. That works with with certified inspectors also. But then you knew that.
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