Wall bracing method #3

[rktect 1]

Quick question.

Can you do wall bracing method #3 for a 2 story (18 feet tall) open space? I have a corner of a house about 18'x18'x2stories tall. Using 2x6 at 16" o.c.

 

[jim baird]

Which code?

 

[north star]

* * * *

rktect1,



Will also need to know your wind & seismic area, in addition

to which code you are using. Also, see the link to the APA

Shear Wall Bracing Handout, Page # 8.

http://www.apawood.org/pdfs/managed/F430.pdf?CFID=12304261&CFTOKEN=61026690

See if this helps you.

* * * *

 

[rktect 1]

Zone 5

Catagory A.

90mph wind

2006 IRC

 

[north star]

* * * *

rkect1,

Table R602.10.1 DOES allow you to perform the Bracing Method # 3.

I'm not exactly sure I am understanding your question. Can you

please clarify the " 18' x 18' x 2 story open space " variable in

your question. Pictures / drawings are always welcomed and help

clarify your question. Also, someone [ on this board ] may see it

and instantly recognize a solution for you.

If you do not perform wall bracing on the open space, how do you

plan to add reinforcement [ to prevent racking ], or means of

attachment [ to prevent separation ] when a strong wind wants to

use that " 18' x 18' x 2 story structure like a kite?

* * * *

 

[Builder Bob]

I don't think that method would be allowable as the IRC has prescriptive limits for stud heights/ platform construction height. If I understand the question correctly, tthis is an open or catheral ceilng space for an assumed great space ...... the platform framing at this location would act as a great hinge point.

 

[rktect 1]

This happens to be a great room. It is a family room that measures 18'x18' square on an exterior corner of the house. It is also 18 feet tall, thus a great room if you will. Lots of glass but enough room to put a 4 foot wide panel on both sides of the exterior corners all the way up 18 feet tall. But I don't see any mention about space heights only stories. Stories are generally separated by floors and joists so I didn't know if removing that floor changed the way this should be braced prescriptively. It seems that if it were continuously sheathed there would be no problem but for some reason with wall bracing methood #3 I have my doubts but nothing concrete to hang my hat on.

 

[north star]

* * * *

Using rktect1's criteria, wouldn't Table R602.3.1 in the `06 IRC allow 18'

heights if supporting a roof only? ( i.e. - "open space", no supported floors )

* * * *

 

[Builder Bob]

I think the answer may be in T602.3 (5)

 

[mtlogcabin]

Agree with Builder Bob this is out of the prescriptive tables in the IRC. Suggest you consult with a structural engineer

 

[FredK]

I like mtcabin's answer. Get an engineer for the bearing wall. Non-bearing wall could be 20 ft according to the table. I suspect one wall will have the roof load.

 

[rktect 1]

section 602.3.1 stud size, height and spacing, exceptions: #2 allow table 602.3.1

I believe you have to look at table 602.3.1 not 602.3(5)

 

[Builder Bob]

Because in I-Code tradtion, the answer you seek is not in Chapter 6 but in Chapter 3. Section 301.3 Story Height - Last Paragraph.

Individual walls or walls studs shall be permitted to exceed these limits as permitted by Chapter 6 provisions, providedstory heights are not exceeded. An engineered design shall be provided for the wall or wall framing members when they

exceed the limits of Chapter 6. Where the story height limits are exceeded, an engineered design shall be provided in accordance

with the International Building Code for the overall wind and seismic force resisting systems.

Thus wall studs and/or walls are limited to twelve feet.......

 

[steveray]

Just to further muddy the waters...by "non-bearing" in Table 602.3(5)...they are just speaking gravity...yes? Wind and seismic? Is not every exterior wall bearing something? Just askin!

 

[globe trekker]

rktect1,

Seems as though we have a difference of code applications. Would you please let

us all know what you decide on doing, ...of which application you choose to use, or

if you decide to use a structural engineer, or something else altogether?

Thanks!

.

 

[rktect 1]

What I did was require the DP to submit a braced wall plan and indicate which bracing methods he was using and where to include:

1. 4 foot wide panel sections.

2. Continuous sheething wall lines.

3. Alternate braced wall panels.

4. Alternate braced wall panels next to doors and windows such as the garage doors.

5. Engineered or manufactured wall panels such as the garage door opening with a wall panel about 12" wide at both ends. (I am still wondering if, because within a 2 foot bumpout he has another double garage bay where he has the alt. methid next to doors and it is within 12.5 feet of the corner of the single bay, if he is required to brace that garage bay.)

6. Method 5 use of gypsum wall board in the interior garage wall line. (This was due more to the REScheck supplied.)

And now I am going to have to go along with builder bob and let them know that for that room an engineered solution is required because he only has room for a 4 foot wide section which would result in sheathed panel 18 feet tall exceeding story height.

I hate the fact they, ICC, insert definitions throughout this code. They should all be listed in the definitions section and if they want to reiterate them again at the beginning of a chapter, fine.

 

[Builder Bob]

I agree.......

 

[rktect 1]

And thanks Bob. I knew something was bothering me. I went to definitions and it only had "story". Which did no good.

 

[rktect 1]

Had one more question. (Ok, its more than one.)

At what point does wall bracing method #3 become something other than method #3? Is there a max. percentage a wall line can be sheathed before it becomes continuous?

Assume a 50 foot long wall. 16% of this wall line is 96 inches of wall panels, so we put a 4 foot panel at both ends and one at 25 feet, about center for 144 inches or about 24% of the wall line This is method #3. If I add 2 more 4 foot panels between the center panel and the end panels, is it still method #3? This would then be 240 inches of panels or about 40% of the wall line. What if I added 2 more sections somewhere and left the rest fenestration. So 336 inches of panels or about 56% of the wall line.

This is really an issue I start to have with the IECC especially when in climate zone 5 we need a R-value of R-20 in walls and the DP specs out an R-3 rigid with R-13 batt with REScheck. Could probably even go R-5 rigid with R-13 batt but now that 56-75% is sheathed structural panels and most of the rest is fenestration what good does the rest of the R-5 do?

 

[peach]

steve.. a non bearing wall supports no roof load (when you're talking exterior walls).. gabled ends. rk.. you'd really have to post a picture of what's proposed.

Thanks

 

[north star]

* * *

rktect1,

The Method # 3 is the ' minimum ' requirements. There's nothing that says

that you cannot exceed the minimums and install additional bracing / panels.

To get your R-20 in the walls, could you use the "spray in foam" to achieve

your IECC requirement, or possibly use the R-5 rigid with the R-13 batt on

top and the insulation paper overlapped and fastened to the outside of the

studs, on the interior side?

* * *

 

[rktect 1]

* * *rktect1,

The Method # 3 is the ' minimum ' requirements. There's nothing that says

that you cannot exceed the minimums and install additional bracing / panels.

To get your R-20 in the walls, could you use the "spray in foam" to achieve

your IECC requirement, or possibly use the R-5 rigid with the R-13 batt on

top and the insulation paper overlapped and fastened to the outside of the

studs, on the interior side?

* * *

Yes I could use spray on/in cell foam insulation but the question really becomes one of how much 1/2" plywood sheathing can I use in conjunction with the 2009 IECC requirement for the R-5/R-13 (method #3 wall bracing system) prior to leaving the wall bracing method #3 where I then have to use R-20 batt insulation only in the wall cavity. 16% is the min.. What is the max. %?

 

[rktect 1]

It seems like I could 1/2" plywood sheath all but a 4 foot long section of a 50 foot long exterior wall, add the 1inch R-3 rigid insulation, put R-13 in the cavity and I would be able to submit a REScheck that says continuous R-5 insulation.

 

[rktect 1]

It seems like I could 1/2" plywood sheath all but a 4 foot long section of a 50 foot long exterior wall, add the 1inch R-3 rigid insulation, put R-13 in the cavity and I would be able to submit a REScheck that says continuous R-5 insulation.

Just answered my own question. It is in the IECC footnote h where it can't cover more than 25% of the exterior wall and if it does it requires an R-2 over the structural sheathing.