8' OSB

[new land owner]

I was wondering what the best way to install 8' OSB?  I have 8' walls with a 2 x 10 floor so I have to cover almost 9'.

Would you hang the OSB 9.5" over the bottom and cut a small piece for the top? 

[MountainDon]

I would buy 4 x 9 foot sheets of OSB. You won't find that at a big box store but a good real lumber yard should. That's what I used.

If you add in a small piece/strip you loose some of the strength the full sheet lends to the wall. Blocking should be added to any panel joints that do not fall over studs or other structural members.  Easier to get the 4x9 IMO. My supplier also carries 4x10 sheets.  Per sq. ft. the 4x9 and 4x10 cost more than the common 4x8, but IMO well worth the strength and convenience.


ED: added link    http://www.norbord.com/OSB_TallWall_Features.shtml

[new land owner]

Don

   I called three local guys and no one has 9' OSB.  My building is going up this weekend and I will have to use 8' OSB.  If that is the case is there any better way to do it?

Tom

[Ernest T. Bass]

How about installing the first row horizontal, and then cut sheets to go vertical from there to the top plate? That way the seam is in the middle of the wall, and the top plate is better anchored down. Perhaps combine that method with the vertical first row and smaller top filler pieces to use up the cutoffs, maybe on the gable ends or something.

[firefox]

I have no idea if this is at all a good idea, but this is what I
might do in a pinch.
Put in 4x4 blocking at the 1 foot hight so that the top 4x8 has a
full 1 3/4" top and bottom to nail to. I would then cut
1x8 strips for the bottom and screw them in place. Then you can use the space to run additional wiring in the future for that add on circuit.
or possibly for those electric base boards.

Others, please feel free to comment for or against this idea.

Bruce

Ofcourse, I would get fanatical and put in an extra vertical 2x4
in all the lower 1 foot section, then drill a 1 inch hole in each
of those 1 foot sections so I could pull and leave a rope to
pull wire if needed in the future. That way all you have to do is make a hole for the box and pull the wire thru with the pull rope
and not have to tear the wall appart. But like I said this is something I might do, not necessarily the right thing to do.

[MountainDon]

Don

   I called three local guys and no one has 9' OSB.  My building is going up this weekend and I will have to use 8' OSB.  If that is the case is there any better way to do it?

Tom

Well probably too late to make a difference by now , but ETBass makes an excellent point about having enough sheathing width the tie the upper plates down. Ditto for the bottom. maybe alternate the sheets; all vertical, one overlapping the bottom and the next overlapping the top. Block all the panel joints and nail well.

[Squirl]

I don't know much, but the faming book I have says, sheet horizontally at the top, sheet horizontally at the bottom, thin strip in the middle.

I couldn't find anything but 8 foot too.

I though sheathing had to be run horizontal anyway?  It covers more studs.  It may be my imagination, but tying 5 studs horizontally in pieces alternating the overlap seams stronger than 3 studs vertically as one piece.

[Squirl]

In addition to just a general sense that I had, my recollection was that sheathing could be thinner and of a lower grade when placed horizontally vs. vertically for PWFs.  I have a general assumption that PWF walls are to be built to with stand greater forces than above grade walls, but I will do more research into this.

http://publicecodes.citation.com/icod/irc/2009/icod_irc_2009_4_sec004_par039.htm

[Squirl]

The only indication I could find in wall sheathing was a footnote that said gypsum sheathing shall be applied vertically.

http://publicecodes.citation.com/icod/irc/2009/icod_irc_2009_6_sec002_par005.htm

[UK4X4]

did you check for Plywood too ?

if your near the sea the local yards will probably stock the larger sheets for boat builders 4x10ft being available too

[rick91351]

OSB is directional and is shown on the stamping.

[Alan Gage]

In addition to just a general sense that I had, my recollection was that sheathing could be thinner and of a lower grade when placed horizontally vs. vertically for PWFs.  I have a general assumption that PWF walls are to be built to with stand greater forces than above grade walls, but I will do more research into this.

http://publicecodes.citation.com/icod/irc/2009/icod_irc_2009_4_sec004_par039.htm

I was researching this when getting ready to sheath my house a couple months ago and read lots of different opinions but somewhere I ran across information from the APA (American Plywood Association) showing the strength of vertical vs. horizontal sheathing.

The gist was that there was virtually no difference between horizontal and vertical sheathing AS LONG AS there was blocking installed along the seam of the horizontal sheathing. Vertical sheathing was considerably stronger than horizontal with no blocking.

Alan

[MountainDon]

Horizontal vs vertical placement. I used to think horizontal was best.

However, there are a few things in code that make me think vertical placement is best.

Shear walls are required, something like every 25 feet I think. Don't hold me to that number! There are many ways to get a shear wall for an 8 ft high wall. The easiest is to use a full sheet, 48 inches wide, of structural rated sheathing, fully nailed on all edges. Vertical.

The fully nailed on all edges means that blocking becomes mandatory and blocking is a PITA, IMO.

[Don_P]

We're also talking about two different forces here.

The reason it is generally suggested to install wall sheathing vertically is that many people do not block the edges, vertical means more edges do fall on framing. I don't believe there is a call for all edges of wall sheathing to be blocked prescriptively... correct me if I'm wrong. Do block all edges and yes blocking sucks. I missed a row in a recent picture I posted and y'all were kind, or you can go looking now  

The strongest way to run sheathing for out of plane bending is horizontally, with the strength axis across the framing. This is why the pwf manual allows a thinner or lower grade if the sheathing is run horizontally.

I had posted awhile ago that it is not recommended to glue wall sheathing but that I could not remember where I had heard it or why. I got the latest JLC and was reading it tonight. Thor Matteson, a structural engineer in CA, author, and poster on a few forums was the source, he wrote that in the "Special Design Provision for Wind and Seismic" that "adhesive attachment of shear wall sheathing shall not be used alone or in combination with mechanical fasteners" There is an exception for seismic zones A,B,C, but only with severe penalty. The entire structural system must be designed to withstand about 4 times the seismic force required for shear panels attached with nails alone.CA is in D,E and F so no glue allowed at all. Glue makes the wall stiffer, remember load goes to stiffness, a glued wall attracts more seismic load than a more flexible nailed wall. The nailed shear wall is more ductile, which in this case is desireable.

And just for semantics, the prescriptive, non engineered walls we would build are called "braced walls". If an engineer calls out and designs the wall it is a "shear wall".

[MountainDon]

I don't believe there is a call for all edges of wall sheathing to be blocked prescriptively... correct me if I'm wrong.

I don't see it spelled out, other than the nailing schedule where it states nails (6D common, 2 x 0.113") on edges will be spaced at 6 inch intervals. I took that to mean all edges. 

[Squirl]

. Spacing of fasteners on floor sheathing panel edges applies to panel edges supported by framing members and required blocking and at all floor perimeters only. Spacing of fasteners on roof sheathing panel edges applies to panel edges supported by framing members and required blocking. Blocking of roof or floor sheathing panel edges perpendicular to the framing members need not be provided except as required by other provisions of this code. Floor perimeter shall be supported by framing members or solid blocking.

Blocking not required I think.  For the suggested blocking, what is recommended 1x or 2x material.

It sounds like 6 one way a half dozen the other.  It seems that for most residential framing the differences aren't significant enough to raise any alarm bells. The APA guides showed both ways and the building code doesn't specify.

Alan I would love to here more about the APA recommendations.


Don_P, I was planning on gluing my wall in seismic zone C. (sorry for the highjack) I was hoping for air sealing and I thought a stronger but stiffer wall was a good thing.  What is required to make it four times stronger for seismic force?

[Don_P]

Not sure Squirl, getting to be bedtime for me as soon as an install manual finishes downloading. I believe the SDPWS manual is on the awc.org site under the publications tab... can't recall if it is free or not. I'd like to hear what you find. Blocking has pretty much got to be 2x to get sufficient penetration from the sheathing nail and attachment to the framing IMO.

MD, not sure, good practice is to block but I've seen plenty of unblocked walls. I've probably used up my welcome for the month at the apa helpdesk... 

[MountainDon]

Braced wall... shear wall... I get the names mixed up. My mind is on shear right now, but a quick look at the IRC does indicate the term braced wall.

Interesting info on the seismic zone C.  I guess it makes sense, permitting some slight flex. Engineers do design buildings with springs and allow sway in tall buildings for earthquake country.

[rick91351]

Don_P  I had a go around with my inspector and he won and as very adamant about direction of OSB.  However it is a shear wall and that very well might have been the reason he would not budge.  Though it was not required to be engineered because it is an AG building.  He required the wall and titled it a shear wall.  I was going to put it in anyway so it was no big deal.  It is in the shop I built last year.  That inspector is an old guy and hard to read.  Sometimes he comes across as being required and other times it is more a helpful suggestion.  This was do it this way or else.   

 

Mountain Don he did mention 6 inch spacing. I screwed one side, shot the other with 2" ring shanks after insulating.   

[MountainDon]

Nails are the listed fastener. No mention of screws anywhere in the walls section of the IRC. Maybe that's one thing he let go as the other side was nailed every six inches.


Too bad not everyone has easy access to 9 or 10 foot panels. It really makes sense to me especially after one takes time to peruse some of the APA info with photos of storm damages. The more edges solidly nailed in with proper size nails and proper spacing, the better.


As for myself I have developed more interest in the subject of stong buildings since discovering that the general area of our mountain property has the following earthquake probability in the next 50 years. Not the worst in the country, but something to think about.

Magnitude     Probability
5.0               24.232%
5.1               21.033%
5.2               18.281%
5.3               15.909%
5.4               13.883%
5.5               12.162%

[rick91351]

Nails are the listed fastener. No mention of screws anywhere in the walls section of the IRC. Maybe that's one thing he let go as the other side was nailed every six inches.
snip--------------------------- snip-------------------------------------------

MD - Thanks for pointing that out.  I knew that about screws but never thought about it on sheeting.  Interesting....  Sort of like the horizontal thing and sheet goods.  I wanted to make it so I could easily pull off the OSB when I decided to finish it off.  It is screwed on the small side.  A room about 18X26.  The other side is about 32x26.  Or we might just leave the OSB and hang peg board and sheet rock, just not there yet.  May never get there as well as slow as I am going right now....        

[Squirl]

It is a free download!
http://www.awc.org/pdf/2008WindSeismic.pdf

Wall Sheathing Table 3.2.1
For out of plane wind load in psf. 7/16 OSB with studs spaced 24" O/C will have a wind load rating of 125 psf for horizontal vs. 25 psf for vertical sheathing.  Plywood has to be four layers to even be placed vertically.

Roof and floor sheathing don't even have the option of being placed parallel to the supports.

Also in tables C3.2A&B, it seems there is no difference in shear capacity, but bending strength is almost five times the amount for perpendicular (horizontal) to the studs vs. parallel (vertical).

In addition a foot note under Table 4.3A lets you increase the value of 7/16 OSB to 15/32 as long as the panels are place long dimension across studs.

There is a diagram of sheathing options labeled as cases 1-6. The option Case 1 is with sheathing horizontally and staggered. It is separated from all other cases as being stronger.

In every instance where there is a difference, sheathing is stronger horizontally.  I believe there is an assumption built in of blocking, as Don had pointed out.

[Don_P]

Cool, I need to download and read that.

Wall Sheathing Table 3.2.1
For out of plane wind load in psf. 7/16 OSB with studs spaced 24" O/C will have a wind load rating of 125 psf for horizontal vs. 25 psf for vertical sheathing.  Plywood has to be four layers to even be placed vertically.

Take that information and go to the wind load tables in chapter 3 of the IRC. I believe that for most wind loading the 25 psf will be sufficient and will avoid alot of blocking. Blocking does turn the individual sheets into one large wall sized diaphragm, so whether required or not, do block. Plywood has to be 4 plies to be placed vertically. I'm just clarifying here, this is one sheet thick. Plywood can be made of varying numbers of plies, 3 ply plywood only has one crossband layer so I do see the logic here. 3 ply 1/2" is really sorry plywood even when run horizontally. The best plywood has what is called balanced construction, an odd number of plies consisting of a core layer and then alternating layers moving outward from that, this stays the flattest.

Read the footnotes of table 602.3(3), I'm looking at the '06, please check other versions if you have time.

Also there is more here; http://www.apawood.org/wallbracing/index.cfm

My comment on braced wall vs shear wall semantics is to make it easier to find the info when searching. In the field the terms a pretty much interchangeable but in the codebook and places like the apa and awc websites you'll get where you're going using braced walls. I'm also muddying sheathing and bracing I think.

Sorry to be short on help, one of those busy weeks.

[MountainDon]

Looking at this topic along with one John just posted ( http://countryplans.com/smf/index.php?topic=11169.msg143040#msg143040 )  makes me think there is really little to be gained by not blocking all wall panel edges no matter where one's building is located.

[new land owner]

Thanks for all of the great feedback!  I am going with the lower panel horizontaly and vertical above.  All seems will be blocked. This will give me nailing for my board and batten siding at 3 and 1/2 feet all around the building.