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Ext. wall OSB...smooth or rough side out

flyreel's picture

A fella I work with installs his ext. wall sheathing (OSB) with the smooth side out (the grade stamp side out).  I've always done it the rough side and nail lines out. His theory is that the smooth side has a wax coating that sheds water more effectively.  I say hogwash.   Even if it did, the housewrap or tar paper, not to mention the finished siding is supposed to keep the water away from the wall structure anyway.  We've had some pretty good discussions, but we can't convince each other.


Bottom line, is there anyone else who installs OSB smooth side out, and what is the reasoning?

(post #103062, reply #1 of 20)

"Hogwash" is correct. I never see/feel wax on OSB, but maybe it is regional?

Bill

(post #103062, reply #2 of 20)

So you can actually see the APA stamp is the only reason I can think of.

Rebuilding my home in Cypress, CA


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(post #103062, reply #3 of 20)

says on the sheet...


out or up...


Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming


WOW!!! What a Ride!
Forget the primal scream, just ROAR!!!

"Some days it's just not worth chewing through the restraints"

(post #103062, reply #4 of 20)

Like IMERC said, ext sheathing is marked which side is supposed to go toward the weather. Sometimes it is hard to read, but, it should be there.

Do everything you do to the very best of your ability, or don't bother doing it at all.

(post #103062, reply #5 of 20)

Smooth side faces into building. I agree w/ your bud that common sense would dictate that the smooth "waxy" side out would protect against weather and swelling issues, etc. But.....every piece I've ever seen that does have a "this side to weather" or "this side down" has without fail been on the smooth side.( plus ,why would the manufacturer put the nailing guide lines on what they intended to be the inside?) I also have heard tell of some gonad -bustin' inspectors raising issues of not being able to read the APA stamp.


Bing

(post #103062, reply #6 of 20)

The rough side is so carps don't fall on their hiney.  It doesn't matter structurally which side is which.


It does look strange if a wall has some rough side out and some smooth so it should be consistant.


I've put the smooth side out to help ice & water stick better when wraping window openings.  As poorly as ice & water sticks to any verticle surface it's probably better to simply use an adhesion primer.


The downside to putting the rough side in is that it increases the amount of unrestrained airflow into and out of the stud cavities.  Want proof?  Build two small boxes from 2x and osb, one rough out and one rough in.  Drill a 1" hole in each and blow into the hole.


Another reason this topic comes up is that it's simply human nature.  We want to know which way something is supposed to go, since it seems logical that there's a right and wrong way.  It's like putting Tyvek with the writting upside down--it just doesn't seem right to many.


It's also funny watching carps installing one of the new roof products that replaces felt.  There are little targets placed all over the surface and it's almost impossible to not want to put the green cap directly on the target.


Good sheathing.


 


Beer was created so carpenters wouldn't rule the world.

 

Beer was created so carpenters wouldn't rule the world.

(post #103062, reply #7 of 20)

Thanks for all of your replies.  I called the APA help line number that is printed on the OSB and the feller said that it didn't matter one way or the other for ext. wall sheathing.  So I guess we're both "right", but I'm still doing it my way.


It's interesting to see how different people with different training, education and jobsite experiences perform everyday tasks such as sheathing, layout, the order in which they nail studs, how they cut crown molding etc. in such different ways and become passionate in defending these ways.


Here's to a beautiful 5 below morning to all...

(post #103062, reply #8 of 20)

BUT ya didn't ask about orintation of the sheet to the studs, joists or rafters.........


Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming


WOW!!! What a Ride!
Forget the primal scream, just ROAR!!!

"Some days it's just not worth chewing through the restraints"

(post #103062, reply #10 of 20)

Well that is another small discussion we've had.  For ext. wall sheathing, I typically run them vertically and he likes them horizontal.  I have spoken to a couple engineers about this and they basically said it didn't matter for most applications.  The reason I run them vertical is to eliminate one row of shear blocking at the edge of the sheet. 


How do you typically orient your wall sheathing?


Thanks


 

(post #103062, reply #11 of 20)

OSB... oriented strand board...


arrows or a statement on the sheet say which way it goes...


 


 


Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming


WOW!!! What a Ride!
Forget the primal scream, just ROAR!!!

"Some days it's just not worth chewing through the restraints"

(post #103062, reply #12 of 20)

Depends on the wall. Which ever is the most efficient for that wall. Perpendicular to supports application with face grain on ply, or manufacturers orientation with OSB or any of that type material applies only to roof or floors.


Life is Good

(post #103062, reply #13 of 20)

manufacturers orientation with OSB or any of that type material applies only to roof or floors.


 


tell that to the inspector...


Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming


WOW!!! What a Ride!
Forget the primal scream, just ROAR!!!

"Some days it's just not worth chewing through the restraints"

(post #103062, reply #15 of 20)

I have , and I have never had an inspector make me change the orientation of wall sheathing.
Right after pointing out to them that the reason they are stamped on the sheets the way they are (16/24, for example) is the first number is given for floor loads , the second for roof loads.
I have seen engineers draw details with sheets oriented only one way , but in questioning them the reason was that they also had drawn the framing members and calculated the shear loads for that detail as a system. Quite often if it was easier to frame by changing the sheathing 90 deg. they would simply give me a detail that showed new perimetr blocking details.
May be differant where you abide, but here it is the way it is.


Life is Good

(post #103062, reply #16 of 20)

if we want to turn the sheets 90 degrees we order the sheets oriantated that way...

Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming


WOW!!! What a Ride!
Forget the primal scream, just ROAR!!!

"Some days it's just not worth chewing through the restraints"

(post #103062, reply #17 of 20)

How do I place OSB in exterior sheathing applications? I don't. it is my personal preference, but, I will never use OSB for any kind of structural application. Plywood is my only choice. Period.


Will this prompt a "nails vs screws" type discussion?

Do everything you do to the very best of your ability, or don't bother doing it at all.

(post #103062, reply #18 of 20)

And if I want to back cut a piece of it I turn my saw blade backward as well. ;-)


Life is Good

(post #103062, reply #19 of 20)

yur sheets made out of vynal???


I take it you doubt it that there are sheets of OSB ortitated across the 4' measure....


but I'm telling ya if the inspector can't see the APA or this side out or the orientation arrow...


you get to do it again or a little something to keep ya busier......


Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming


WOW!!! What a Ride!
Forget the primal scream, just ROAR!!!

"Some days it's just not worth chewing through the restraints"

(post #103062, reply #20 of 20)

  Simpson has a technical bulletin on this (panels horizontal or vertical) titled Understanding the performance of wall sheathing used to resist simultaneous uplift and shear loads.  A couple of the points are "panels should be installed with the face grain parallel to the studs (vertically)" and "all horizontal panel joints must occur over framing".


      Keith

(post #103062, reply #9 of 20)

Ask your buddy what the nail lines are for. 

(post #103062, reply #14 of 20)

My "mentor" always put the smooth side out.  He felt that the friction caused by the rough side attached to the studs would help shear value :-)  He would do this with the OSB tread material too. 


The rough side is made for safer walking.  Its been awhile but that was one of the "benefits" to OSB that was listed on one of the manufacturer's websites.  Also, the nailing lines are always on the rough side and the stamps on the smooth side.  So the inspector can see the roof sheathing stamp and the wall sheathing stamp from inside the house or he can look up for the subfloor (except the first floor).


We use 9 and 10' OSB regularly and they always say (brands we use) not to use for roof sheathing.  I think part of that is because both sides are smooth.

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