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Subject Author Date
Structural framing query Dan Deckert 02-18-2007
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Posted by Bobk207 on February 22, 2007, 1:22 am
>
>
> > Dan-
>
> > >>>>The owner is looking at different methods that will meet/exceed any
current
> > codes<<<<<<
>
> > if he's looking to meet or exceed a code....we kinda have to know
> > which one OR at the very least where the building is going to be;
> > snow? wind? seismic?
>
> OK Bob, I''ll try to cover this.
> Building in NE Wa. St. Snow load is @ least rated @ 3'. Wind is zero.
Siesmic.?? unk 60 miles +/- north of Spokane
>
>
>
> > desired performance level? life safety only? moderate damage from a
> > 50 year event? minimal damage? fully elastic?
>
> A minimal workshop for life.
>
> > >>>>>>As in why install fire blocking if the interior is open? <<<<<
>
> > I must have missed that in the OP, nothing on the interior?
>
> Nope! Well, insulation between the studs.
>
> > Why cut diagonal 2x6's into the face for shear if you can use properly
attached
> > metal strapping with the addition of the exterior <,,
>
> > Metal strapping is an alternative to a let-in brace system, not much
> > of an alternative IMO
>
> > I've tested let-in braces (1x4 or 1x6) in a 2x6 wall.....they're
> > amazingly strong, IMO straps are a crappy cheap alternative. Who
> > came up with a 2x6 let-in brace?
>
> Now here's the question, why can't metal banding/strapping work, properly
applied, as well as cut in diagonal bracing for shear? Whether it's
interior/exterior or both?
>
> > >>>>>exterior 1x4's with metal siding?<<<<<<
>
> > Is the metal siding, siding or structural sheathing? What are the
> > surfaced mounted 1x4's supposed to accomplish? How thick is the steel
> > "sheeting"; flat or corrugated / ridged? fastener style, size &
> > spacing?
>
> Corrugated wall sheathing. 1.5" highs. Ribbed panels as in a PEB.
>
> > How is metal supposed to work as structural sheathing if it's held off
> > the framing (studs) by the surface mounted 1x4's ? what is the
> > estimated demand on the 1x4 when it acts as "shear transfer
> > blocking"? Is 1x4 adequate to provide continuity of load path for the
> > metal sheathing? I doubt it.
>
> Therein was a purpose for my query. I stated my expertise relative to wood is
nil.
>
> > In order to design something like this this (& not use a code,
> > convention construction or a prescriptive design methodology) you have
> > bounce back & forth between "capacity" & "demand" and constantly
> > thinking about load path .....
>
> yep!
>
> > Oh but not foundation or any of the other "off limits" topics from the
> > OP.
>
> Bob, you know as well as I do, there are extraneous answers and queries
unrelated to a post that detour from the OP. I just wanted to avoid the
extraneous and subjctive stuff. Albeit it seemed to irritate some....
>
> > What's gonna hold this thing together when the wind sucks the roof off
> > as a single unit.....better not discuss any hurricane ties.
>
> Here and again, we're not at that point in the design, henceforth, irrelevant.
I'm just asking about a DCN for a wall.
>
> > Just because the process might appear to be simple (it ain't) or the
> > process appears easy (it is, IF you know what you're doing; & know
> > what to consider, what to ignore......it's called experience)
>
> Been there, done that! But my experience is primarily steel. Which is why I
asked about the faced 1x4 for shear, with the metal wall sheathing. A PEB is a
freak until the wall sheets are applied to get shear.
>
> > Seismic in Texas...probably not a huge factor, wind in WA....maybe
> > something to consider
>
> No wind in 60 years. Per owners father that lives there.
>
> > Snow is Orange County, CA not a concern snow in WA....I don't
> > know, I'd have to check.....elevation
>
> Elev. unk. <3000' Snow loads are a different consideration but will be
addressed for enginereed trusses and purlins.
>
> > Snow in SoCal not a problem....oops! I forgot to tell you, the
> > building site is at 6000 ft! & the roof slope is only 4/12! Got me a
> > cheap set of plans off the internet.
>
> LOL................................
>
> Lookin fwd to hearin from you.....................
> Dan
>
> > cheers
> > Bob
>
> > btw construction ain't design & design ain't construction......but
> > both are required to get the job done.
>
> AMEN to that. Can you plz fwd that to our engineers and fabricators? I've got
over 300 manhours in rework and some of it is from going to hell to get it done.
>
> > The best jobs are gotten when each part considers the other.........
>
> best jobs?, consideration? what the hell are those? ;-)
> Dan




Dan-

I give up, too many variables floating in the wind.......overall
objective unclear (minimze labor cost?)

as are desired performance levels & building configuration

for example....

> > >>>>>>As in why install fire blocking if the interior is open? <<<<<
>
> > I must have missed that in the OP, nothing on the interior?
>
> Nope! Well, insulation between the studs.

It's either open on the interior or it ain't......which it is will
drive the design.


another example

>I just wanted to avoid the extraneous and subjective stuff. Albeit it seemed to
irritate some....
>
> > What's gonna hold this thing together when the wind sucks the roof off
> > as a single unit.....better not discuss any hurricane ties.
>
> Here and again, we're not at that point in the design, henceforth, irrelevant.
I'm just asking about a DCN for a wall.

What you consider extraneous may important to the building
designer......

"we're not at that point in the design, henceforth, irrelevant."

again, might be best to consider it now......IMO best design practice
is to bounce between "the big picture" & the "details" ....leaving
stuff off until later invites re-design.... a balance is needed

enough "big picture" & "details" to move the project forward w/o
having to redo stuff.


>>>>Everything will meet or exceed any codes.<<<<

How can you possibly say that with any certainty?

>>> The owner is just looking for alternatives to beat the costs of
construction costs (read labor costs)as in standard framing. <<<

Pretty hard to beat stick framing & wood sheathing for speed of
construction & minimal labor. Gun nails are faster than screws.

>>Basically speaking, everything will be be overbuilt. It comes from working
for the federal govt. where he is employed. <<<<

Again, how can you possibly know it will be "overbuilt"? Using
excessive amounts of material or overly large members might seem
"overbuilt" but it may not result in an increase in strength....just
wasted material...

for example using 2x6 framing over 2x4 framing in a standard 8'
plywood shear wall will buy you little increased strength. Thicker
plywood without bigger nails or more frequent nailing again won't buy
much improved performance.


This project needs a lead designer who can interact with the customer;
someone who understands design & construction and can get the owners
desires on paper.

cheers
Bob



Posted by Michael Bulatovich on February 22, 2007, 7:35 am

>>
>>
>> > Dan-
>>
>> > >>>>The owner is looking at different methods that will meet/exceed any
>> > >>>>current
>> > codes<<<<<<
>>
>> > if he's looking to meet or exceed a code....we kinda have to know
>> > which one OR at the very least where the building is going to be;
>> > snow? wind? seismic?
>>
>> OK Bob, I''ll try to cover this.
>> Building in NE Wa. St. Snow load is @ least rated @ 3'. Wind is zero.
>> Siesmic.?? unk 60 miles +/- north of Spokane
>>
>>
>>
>> > desired performance level? life safety only? moderate damage from a
>> > 50 year event? minimal damage? fully elastic?
>>
>> A minimal workshop for life.
>>
>> > >>>>>>As in why install fire blocking if the interior is open? <<<<<
>>
>> > I must have missed that in the OP, nothing on the interior?
>>
>> Nope! Well, insulation between the studs.
>>
>> > Why cut diagonal 2x6's into the face for shear if you can use properly
>> > attached
>> > metal strapping with the addition of the exterior <,,
>>
>> > Metal strapping is an alternative to a let-in brace system, not much
>> > of an alternative IMO
>>
>> > I've tested let-in braces (1x4 or 1x6) in a 2x6 wall.....they're
>> > amazingly strong, IMO straps are a crappy cheap alternative. Who
>> > came up with a 2x6 let-in brace?
>>
>> Now here's the question, why can't metal banding/strapping work, properly
>> applied, as well as cut in diagonal bracing for shear? Whether it's
>> interior/exterior or both?
>>
>> > >>>>>exterior 1x4's with metal siding?<<<<<<
>>
>> > Is the metal siding, siding or structural sheathing? What are the
>> > surfaced mounted 1x4's supposed to accomplish? How thick is the steel
>> > "sheeting"; flat or corrugated / ridged? fastener style, size &
>> > spacing?
>>
>> Corrugated wall sheathing. 1.5" highs. Ribbed panels as in a PEB.
>>
>> > How is metal supposed to work as structural sheathing if it's held off
>> > the framing (studs) by the surface mounted 1x4's ? what is the
>> > estimated demand on the 1x4 when it acts as "shear transfer
>> > blocking"? Is 1x4 adequate to provide continuity of load path for the
>> > metal sheathing? I doubt it.
>>
>> Therein was a purpose for my query. I stated my expertise relative to
>> wood is nil.
>>
>> > In order to design something like this this (& not use a code,
>> > convention construction or a prescriptive design methodology) you have
>> > bounce back & forth between "capacity" & "demand" and constantly
>> > thinking about load path .....
>>
>> yep!
>>
>> > Oh but not foundation or any of the other "off limits" topics from the
>> > OP.
>>
>> Bob, you know as well as I do, there are extraneous answers and queries
>> unrelated to a post that detour from the OP. I just wanted to avoid the
>> extraneous and subjctive stuff. Albeit it seemed to irritate some....
>>
>> > What's gonna hold this thing together when the wind sucks the roof off
>> > as a single unit.....better not discuss any hurricane ties.
>>
>> Here and again, we're not at that point in the design, henceforth,
>> irrelevant. I'm just asking about a DCN for a wall.
>>
>> > Just because the process might appear to be simple (it ain't) or the
>> > process appears easy (it is, IF you know what you're doing; & know
>> > what to consider, what to ignore......it's called experience)
>>
>> Been there, done that! But my experience is primarily steel. Which is why
>> I asked about the faced 1x4 for shear, with the metal wall sheathing. A
>> PEB is a freak until the wall sheets are applied to get shear.
>>
>> > Seismic in Texas...probably not a huge factor, wind in WA....maybe
>> > something to consider
>>
>> No wind in 60 years. Per owners father that lives there.
>>
>> > Snow is Orange County, CA not a concern snow in WA....I don't
>> > know, I'd have to check.....elevation
>>
>> Elev. unk. <3000' Snow loads are a different consideration but will be
>> addressed for enginereed trusses and purlins.
>>
>> > Snow in SoCal not a problem....oops! I forgot to tell you, the
>> > building site is at 6000 ft! & the roof slope is only 4/12! Got me a
>> > cheap set of plans off the internet.
>>
>> LOL................................
>>
>> Lookin fwd to hearin from you.....................
>> Dan
>>
>> > cheers
>> > Bob
>>
>> > btw construction ain't design & design ain't construction......but
>> > both are required to get the job done.
>>
>> AMEN to that. Can you plz fwd that to our engineers and fabricators? I've
>> got over 300 manhours in rework and some of it is from going to hell to
>> get it done.
>>
>> > The best jobs are gotten when each part considers the other.........
>>
>> best jobs?, consideration? what the hell are those? ;-)
>> Dan
>
>
>
>
> Dan-
>
> I give up, too many variables floating in the wind.......overall
> objective unclear (minimze labor cost?)
>
> as are desired performance levels & building configuration
>
> for example....
>
>> > >>>>>>As in why install fire blocking if the interior is open? <<<<<
>>
>> > I must have missed that in the OP, nothing on the interior?
>>
>> Nope! Well, insulation between the studs.
>
> It's either open on the interior or it ain't......which it is will
> drive the design.
>
>
> another example
>
>>I just wanted to avoid the extraneous and subjective stuff. Albeit it
>>seemed to irritate some....
>>
>> > What's gonna hold this thing together when the wind sucks the roof off
>> > as a single unit.....better not discuss any hurricane ties.
>>
>> Here and again, we're not at that point in the design, henceforth,
>> irrelevant. I'm just asking about a DCN for a wall.
>
> What you consider extraneous may important to the building
> designer......
>
> "we're not at that point in the design, henceforth, irrelevant."
>
> again, might be best to consider it now......IMO best design practice
> is to bounce between "the big picture" & the "details" ....leaving
> stuff off until later invites re-design.... a balance is needed
>
> enough "big picture" & "details" to move the project forward w/o
> having to redo stuff.
>
>
>>>>>Everything will meet or exceed any codes.<<<<
>
> How can you possibly say that with any certainty?
>
>>>> The owner is just looking for alternatives to beat the costs of
>>>> construction costs (read labor costs)as in standard framing. <<<
>
> Pretty hard to beat stick framing & wood sheathing for speed of
> construction & minimal labor. Gun nails are faster than screws.
>
>>>Basically speaking, everything will be be overbuilt. It comes from
>>>working for the federal govt. where he is employed. <<<<
>
> Again, how can you possibly know it will be "overbuilt"? Using
> excessive amounts of material or overly large members might seem
> "overbuilt" but it may not result in an increase in strength....just
> wasted material...
>
> for example using 2x6 framing over 2x4 framing in a standard 8'
> plywood shear wall will buy you little increased strength. Thicker
> plywood without bigger nails or more frequent nailing again won't buy
> much improved performance.
>
>
> This project needs a lead designer who can interact with the customer;
> someone who understands design & construction and can get the owners
> desires on paper.

Sounds like *work*. <shudders>
--


MichaelB
www.michaelbulatovich.ca



Posted by Bob Morrison on February 21, 2007, 10:20 am
In a previous post Dan Deckert wrote...
> Bob,
> Therein lies the gist of my query. According to the property owner, the only
> inspection required is septic and power. Building permit comes from the
> county with no plan review, according to the owner and I've never known this
> guy to lie. Seemed strange to me but.........Building is in the county.

Sounds like one of the rural counties (Pend Oreille? Ferry?). The fact
that there is little plan review does not eliminate the need to build
according to the state building code, which is IBC2003 for this type of
building.

> > The owner asked for a mix of design. He didn't want a full blown wood framed
> wall as one usually would. He wanted to eliminate the fire blocking,
> although the walls are 16' high, because the interior is not covered
> (sheetrock/OSB, etc.) in any way. It would be open like a pole building on
> the interior with faced insulation between the studs.

As soon as he puts in insulation he needs fire blocking.
>
> I asked if the wood diagonal bracing could be replaced with properly
> fastened steel banding to provide shear loads because the owner asked. Much
> like diagonal cabling or diagonal brace rods in a PEB. The exterior of the
> building will be gauge metal sheets. Hence my question of the 1x4's with the
> wall sheets as a part of the shear. The 1x4's would act as sheeting girts
> like a PEB or pole building. Owner has no plans to install OSB or like
> sheathing to the exterior walls. Owners comment was if he can do it
> differently and faster and cheaper but still be solid as hell and meet or
> surpass any codes that might come up, why not.

The fact that the building is a hybrid means it requires engineering. A
building with 16-foot walls is a pretty significant structure, even if it
is only made of wood. I think you should insist on engineering, if
nothing else for your own protection. If something happens to the
building, your contractor's license is in jeopardy.

Perhaps the short answer to your questions might be something like this,
"Maybe". The use of bracing of any type in lieu of shear walls requires
an engineered design according to IBC2003. The fact that the walls are
over 16-feet tall requires an engineered design. The county may not do a
complete plan review, but I would not be surprised that they would require
an engineered design as part of the submittal package (even if they don't
understand it).

Please don't misunderstand. I'm not lobbying for more work for myself.
I've got too much on plate as it is. If your friend needs help finding an
engineer, then I may be able to help with that.

--
Bob Morrison, PE, SE
R L Morrison Engineering Co
Structural & Civil Engineering
Poulsbo WA
bob at rlmorrisonengr dot com

Posted by Dan Deckert on February 21, 2007, 11:50 pm

> In a previous post Dan Deckert wrote...
> > Bob,
> > Therein lies the gist of my query. According to the property owner, the
only
> > inspection required is septic and power. Building permit comes from the
> > county with no plan review, according to the owner and I've never known
this
> > guy to lie. Seemed strange to me but.........Building is in the county.
>
> Sounds like one of the rural counties (Pend Oreille? Ferry?). The fact
> that there is little plan review does not eliminate the need to build
> according to the state building code, which is IBC2003 for this type of
> building.
>
> > > The owner asked for a mix of design. He didn't want a full blown wood
framed
> > wall as one usually would. He wanted to eliminate the fire blocking,
> > although the walls are 16' high, because the interior is not covered
> > (sheetrock/OSB, etc.) in any way. It would be open like a pole building
on
> > the interior with faced insulation between the studs.
>
> As soon as he puts in insulation he needs fire blocking.
> >
> > I asked if the wood diagonal bracing could be replaced with properly
> > fastened steel banding to provide shear loads because the owner asked.
Much
> > like diagonal cabling or diagonal brace rods in a PEB. The exterior of
the
> > building will be gauge metal sheets. Hence my question of the 1x4's with
the
> > wall sheets as a part of the shear. The 1x4's would act as sheeting
girts
> > like a PEB or pole building. Owner has no plans to install OSB or like
> > sheathing to the exterior walls. Owners comment was if he can do it
> > differently and faster and cheaper but still be solid as hell and meet
or
> > surpass any codes that might come up, why not.
>
> The fact that the building is a hybrid means it requires engineering. A
> building with 16-foot walls is a pretty significant structure, even if it
> is only made of wood. I think you should insist on engineering, if
> nothing else for your own protection. If something happens to the
> building, your contractor's license is in jeopardy.
>
> Perhaps the short answer to your questions might be something like this,
> "Maybe". The use of bracing of any type in lieu of shear walls requires
> an engineered design according to IBC2003. The fact that the walls are
> over 16-feet tall requires an engineered design. The county may not do a
> complete plan review, but I would not be surprised that they would require
> an engineered design as part of the submittal package (even if they don't
> understand it).
>
> Please don't misunderstand. I'm not lobbying for more work for myself.
> I've got too much on plate as it is. If your friend needs help finding an
> engineer, then I may be able to help with that.
>
> --
> Bob Morrison, PE, SE
> R L Morrison Engineering Co
> Structural & Civil Engineering
> Poulsbo WA
> bob at rlmorrisonengr dot com

Bob,
Everything will meet or exceed any codes. The owner is just looking for
alternatives to beat the costs of construction costs (read labor costs)as in
standard framing. Basically speaking, everything will be be overbuilt. It
comes from working for the federal govt. where he is employed. Like I
stated, he's looking for alternatives to the labor side. His stepson is
working for licensed contractors putting up wood framed houses/etc. (10
years) and has some idea of what's going on. But the owner is looking for
ways to do different things to cut costs.

I was just looking for opinions on the design change. Little did I surmise
it would create so much controversy/recoil for what I considered a simple
change.


Dan























Posted by Bob Morrison on February 22, 2007, 10:21 am
In a previous post Dan Deckert wrote...
> Everything will meet or exceed any codes. The owner is just looking for
> alternatives to beat the costs of construction costs (read labor costs)as in
> standard framing. Basically speaking, everything will be be overbuilt. It
> comes from working for the federal govt. where he is employed. Like I
> stated, he's looking for alternatives to the labor side. His stepson is
> working for licensed contractors putting up wood framed houses/etc. (10
> years) and has some idea of what's going on. But the owner is looking for
> ways to do different things to cut costs.
>
> I was just looking for opinions on the design change. Little did I surmise
> it would create so much controversy/recoil for what I considered a simple
> change.
>

Dan:

When the proposed structure is outside the normal framing methods then it
is bound to start a controversy. I understand the concept of trying to
cut costs. I make my best attempt to save the owner the cost of my fee in
the details of every design I do.

I will repeat: a building with 16-foot high walls is anything but ordinary
and should be engineered. There is no "build in excess of code" here,
because the code does not directly address this type of building.

Does this mean strap bracing or even using the steel siding for its shear
value is out of the question? No, it doesn't. But, only an engineered
design can answer these questions. And that's the point I want to make.
Trying to save a couple thousand bucks in engineering fees is not the
answer if the building is under-designed from the start.

As for loads, minimum ground snow load per SEAW Snow load manual =
somewhere between 45 psf and 80 psf depending on project location.
Minimum wind load is based on 85 mph (3 second gust) per state building
code. If the building is fully enclosed then the 10 psf minimum rule will
probably govern. If the building is only partially enclosed, then the
design gets more complicated. Seismic load will be minimal, but not non-
existent. For a light structure such as that proposed, wind load will
definitely govern.

I recently designed a shop/garage building in the Quilcene area using
embedded poles. Eave height was only 9 feet. The building was not,
however, a conventional pole building since the contractor did not want to
deal with the heavy bolted truss connections required because of the labor
involved. The roof system was metal over a plywood diaphragm transferring
loads to the end walls. The end walls were plywood sheathed with metal
siding. The back wall was metal siding only because it was a long wall
and the shear value of the siding was sufficient to act as a shear wall.
Shear walls were attached to the poles via strut/plate at the bottom of
the wall. Pole embedment carried the loads into the ground.

The above example is intended to show that it is possible to design
unconventionally framed structures to save labor, but they must be
properly engineered.

--
Bob Morrison, PE, SE
R L Morrison Engineering Co
Structural & Civil Engineering
Poulsbo WA
bob at rlmorrisonengr dot com

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