Brick veneer prohibited in wood construction for SDC E?

[sponton]

I am designing a really simple one story light frame [wood] building for a place with a Seismic design category E, when I was reading the special inspections and the requirements for masonry, there was no information that prohibited me from having veneer. Then somebody kindly pointed out Section 2308.12.2 from the IBC and it reads:

2308.12.2 Concrete or masonry.
Concrete or masonry walls or masonry veneer shall not extend above the basement

Is this requirement for load bearing masonry, cause it doesn't make sense to me how it shouldn't be extended above the basement. There's also a few exceptions for SDC D regarding bracing of the veneer wall. Is there also an exception to SDC E? I read somewhere that it is possible to use if you have joint reinforcement at a max. of 18" and isolate the wall from taking any lateral seismic loads.

Could anybody share some light on this, point me to a reference to justify its use and such, I'd appreciate it.

 

[msquared48]

I do not have access to a copy right now, but could they be speaking of "unreinforced" concrete or masonry?

Very hard to believe that reinforced concrete or masonry shear or bearing walls could not extend above the basement.

Mike McCann, PE, SE (WA)

 

[WARose]

The IRC pretty much kicks you out of the code (into the IBC) for their SDC E. (I've never quite gotten the relationship since the IRC has seismic sub categories D[sub]0[/sub], D[sub]1[/sub], etc that the IBC doesn't have.)

In any case, section 2308, I think, is a prescriptive approach (sort of like a mini-IRC). There is nothing stopping you (as far as I know) from engineering a solution outside of that. In that vein, ACI 530 does not prohibit you from have masonry (veneer or otherwise) in SDC E....at least in the version I have. (There are (of course) numerous requirements for reinforcement, connectors, etc.)

 

[sponton]

It isn't clarified. It just says that's not permitted for conventionally framed structures. Oddly enough the TMS 402-13/ACI 530-13/ASCE 5-13 doesn't say anything against its use. Also the IBC Chapter 14 [?] Exterior walls allows brick veneer in SDC E if it complies with the requirements of chapter 12 of the TMS 402-13/ACI 530-13/ASCE 5-13.

It also says that you can't have a higher than a two story conventionally framed wood building if the SDC is C. This contradicts the limitation of the ASCE on buildings laterally supported by conventional light framed shearwalls which is 65'.

 

[sponton]

@WARose

Oh ok,I guess i'll just ditch the whole section. My main problem is that I find the lack of a clear definition of what conventional light frame construction is, I will agree that there's a section for ASD, another for LRFD and then the one for conventionally framed construction which would imply that it's not engineered. The first few subsections of 2308 state that I can skip height limitations on 2308.2 if the solution is engineered, but then it doesn't say anything else regarding the other sections. If it is indeed just a prescriptive approach, I can see why they would want to limit the type of construction to this extent but at least it should be clearly stated that you do not have to abide by that section if you're engineering the solution, specially when they define conventional light frame construction as

CONVENTIONAL LIGHT-FRAME CONSTRUCTION. A type of construction whose primary structural elements are formed by a system of repetitive wood-framing members. See Section 2308 for conventional light-frame construction provisions.

Which is just so generic it can fit anything else.

Anyways, thanks both of you.

 

[JAE]

Yes, the whole section 2308 in the IBC is a special set-aside method of construction where you are essentially leaning back to IRC-type construction.
Re-read section 2308.1 where it states that "other" things can be used based on other parts of the IBC as long as they are engineered properly.
But INSIDE 2308, the limitation of masonry above grade applies only to structures that are designed based on 2308.

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[masonrygeek]

And to add to this discussion, IBC Section 2308 mentions "stone or masonry VENEER" so this doesn't apply to reinforced masonry or other loadbearing masonry elements. Since all of the exceptions talk about bracing and hold-down connectors there is a concern with the heavy weight of the veneer on a light frame wood wall. So for the wood frame design you need to do the extra things to the wood frame listed in the exceptions to use masonry above a basement. From the brick veneer standpoint, you can use brick veneer in these high SDC applications, but all you may need to do is space your veneer ties closer together (Chapter 12 of ACI530/TMS402). And as most folks here have said, these are mostly prescriptive requirements and as soon as you do some engineering analysis those prescriptive requirements go away.

Or you could just use all loadbearing masonry construction and forget about the wood!