1/2 plywood vs. 7/16 OSB sheathing

Started by pioneergal, December 11, 2005, 08:24:23 PM

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pioneergal

How does 1/2 plywood compare to 7/16 OSB as sheathing for exterior walls and for the roof?

Which would be the best product for the task before us?

Would it be to our benefit to use something else?

PEG688

Now  IMO and "if" I can talk the client into the few extra dollars , I use 7/16 OSB on the side walls , it's as good as CDX you'll be able to buy , plywood /real wood all is going down hill fast IMO .

 I like to useat least 1/2  CDX on the roofs , I do two plywood clips between 2' OC truss's , and one clip on 16" OC rafters .

 MY CHOICE IF IT WHERE MINE , or the client goes for it is [highlight], 5/8 " CDX on [/highlight][highlight]the roof [/highlight], with one plywood clip if 2' OC truss, no clip if 16" OC rafter.   I really like the "bite" the roofing nail gets in the 5/8 CDX , and really think/ know  in the 7/16" OSB there is no holding power in the nail , they sort of feel "greased "when you go back to repair them / or remodel .
 Yes they hold mostly in shear but wind don't understand that it ain't suppost to lift stuff , so wind can lift easier / easly OSB nailed roofing , IMO .
   I also like comp shingles HAND NAILED , no guns , no staples on comp roofing, or cedar shakes / shingles .

 Hope this helps , PEG


When in doubt , build it stout with something you know about .


Ryan B

I have used both types – on my own home and on other houses.
I have come to somewhat of a conclusion based on actual use and some backyard tests – well actually "during installation" tests but let's not tell the client.

I believe strength tests on either product performed by a lab to a certain load will be the same - these products test the same and are marketed this way. Most codes and builder guide lines recognize those facts and treat them equally.
My field tests indicate that the wafer board does fail sooner than CDX when you apply high loads that the product would rarely be seen in service. Typically the load I apply is a 210lb uniform load (same size as a size 12 boot) on a unsupported edge.
If given the same mill and close manufacturing dates the wafer board will always be of a better manufacture, this means straighter and square, than CDX.
CDX does seem to hold a screw better if you're using a metal roof.
Wafer board will swell more than CDX when wet and should be spaced accordingly if it is going to see wet service before being covered - roof or wall. An 8d nail works quite well as a spacer.
Fresh wafer board will shrink (you can actually see the darker wetter oval in the middle if your supplier is near a plant) but I like to gap anyway due to length of my projects.
Wafer board often has layout lines – a time saver.
As the plywood market got competitive – around here about $10 a sheet – the CDX product turned to crap. Delamination, missing plys, too much glue, no glue, out of square ect. It was no problem to return, just lost time. Those were the days!
As the price of CDX raised so did the quality of the product.
Current state codes in my area require no clips with either product
5/8 wafer is stronger than ½ CDX but it is also heavier – price is close at this comparison.
5/8 CDX has just about won me due to the quality of ½ CDX

I like to use 1/2 CDX (order 1% extra) for the roof and 7/16 wafer for the walls based on the above items. Hope this helps
Happy sheeting,
Ryan B

PEG688


Current state codes in my area require no clips with either product
5/8 wafer is stronger than ½ CDX but it is also heavier – price is close at this comparison.
5/8 CDX has just about won me due to the quality of ½ CDX

Never said I had to use clips , just think it's  better  ;) Sort of your boot test , wonder if anyone will listen , most/ some  clients only see the bottom line $$$$ Oh well the jobs we lose, we probably are better off in the long run , without them . PEG
When in doubt , build it stout with something you know about .

glenn kangiser

#4
Quote
Some  clients only see the bottom line $$$$ Oh well the jobs we lose, we probably are better off in the long run , without them . PEG

Good point there , PEG -- I have found over 31 years of being self employed that if I have a problem with a potential customer while negotiating the sale or during preliminary discussions including pricing, then I am better off losing the sale.  I will negotiate price within reason.

Monitoring the job after someone else got it has proven that to be right in some cases, although I got one where I prevailed in negotiations and while the project manager started out wearing a suit everyday and being a bit of a jerk, by the end of the job he was coming to work in blue jeans and turned out to be a pretty good guy.
"Always work from the general to the specific." J. Raabe

Glenn's Underground Cabin  http://countryplans.com/smf/index.php?topic=151.0

Please put your area in your sig line so we can assist with location specific answers.


PEG688

#5
Yup One in a 100 turn out good .   We did a job for a well to do client , quite a arse last winter . it ran over weather on a beach , looking west on Whidbey Isl .  He read me up one side down the other to the point I said I'm done call the office , and I did just that shut me cake hole , walked away . Later in the job his sewer s not working , of cousre it has to be us , well to be helpful I do some trouble shooting with him to be nice . WE pull the lid off the septic tank , one screw won't come out to much dirt around it I see a 90° PVC fitting not connected and say there's the problem  I'm holding the lid back and up ," put that back on "I say  , When he does it blows air down , as it was some funkie airarated system, it blows the poop up , He cuts and runs I LMAO , when he came back over I said "Well one thng we both know is your sh&t does stink, and we didn't cause your sewer problem . " MTL it never did work as that joint failed at the time it was installed three months before , sort of a new begining .

 That one I should send into FHB for the back page Moments in building , or some such. PEG    
When in doubt , build it stout with something you know about .

pioneergal

QuoteHow does 1/2 plywood compare to 7/16 OSB as sheathing for exterior walls and for the roof?


All of the responses have been great............thanks to all.

I probably should have mentioned in my orignal post the purpose for my asking.

We were at Home Depot on Sunday evening making a purchase and browsing when we saw  the 1/2 Ply displayed by the 7/16 OSB.

There was only a dollars difference between the 2 products  ....

1/2 Ply = $11.99  

7/16 OSB = $10.99

We don't have a lot of $'s but would rather spend a little extra now if it's necessary than to spend $'s and time in repairs later.

We're rookies leaning on the advice of friends and all of you kind folks on this forum that have been so kind in your postings.

If I can figure out how to post pictures I would like to share with the forum our progress to date.


God Bless


Leo

I went with the cdx hoping it will hold up under moisture better till all is closed in or if my 28'by 48'tarp becomes airborn again.I did see a house that was covered with osb and gived one coat of  cheap paint about a dozen years ago?It looked as if it was wearing a fur coat.there were places where the osb was gone but overall it held up better than anyone would have thought?

PEG688

Oh BTW Gal if you do use the OSB on the roof make sure you put the rough side up , the slick side on side walls can go in or out . But on the roof top you'll want the rougher side up , much better grip on the boots / shoes .

 And like the last post if it's going to be a few months till you can cover ,,some cheap paint on your cuts would I think help.  The stuff that is factory edge is already sealed with something , buttering up your cuts might be cheap insurance or at least you tried , effort is always good .

 Good Luck , PEG
When in doubt , build it stout with something you know about .


bayview

Hi,

  We just recently finished our garage with 1/2" cdx on exterior walls and roof.  Roof decking was on trusses 24" on center.  Exterior walls were 2" X 6" 24" on center.  (OSB 7/16" was $11.99 and CDX 1/2" was $12.99)  

  If we were to do it again, I would spend the extra $ for 5/8 cdx on the roof.  I weigh almost 300 lbs. and was very nervous when walking on that roof !!!  Thought I was going through a couple of times.  Lots of flexing.  We used 2 plywood clips between each truss.  The difference in cost would have been $7.00 a sheet.  I used 22 sheets for the roof.  $154.00 extra (CDX 5/8" was $19.99)  Would have been money well spent.

  Finished exterior with hardiplank siding.  I felt the Hardiplank was worth the extra time and money.  It was hard to cut unless using the special hardi blade in a circular saw.  The siding would just eat up carbide blades.

 I agree with Peg, to hand nail shingles.  I started with a nailing gun.  Some nails would end to deep. And some were set high, so I had to drive them with a hammer anyway.  

  Good Luck . . .
    . . . said the focus was safety, not filling town coffers with permit money . . .

PEG688

QuoteHi,

  We just recently finished our garage with 1/2" cdx on exterior walls and roof.  Roof decking was on trusses 24" on center.  Exterior walls were 2" X 6" 24" on center.  (OSB 7/16" was $11.99 and CDX 1/2" was $12.99)  

  If we were to do it again, I would spend the extra $ for 5/8 cdx on the roof.  I weigh almost 300 lbs. and was very nervous when walking on that roof !!!  Thought I was going through a couple of times.  Lots of flexing.  We used 2 plywood clips between each truss.  The difference in cost would have been $7.00 a sheet.  I used 22 sheets for the roof.  $154.00 extra (CDX 5/8" was $19.99)  Would have been money well spent.

  Finished exterior with hardiplank siding.  I felt the Hardiplank was worth the extra time and money.  It was hard to cut unless using the special hardi blade in a circular saw.  The siding would just eat up carbide blades.

 I agree with Peg, to hand nail shingles.  I started with a nailing gun.  Some nails would end to deep. And some were set high, so I had to drive them with a hammer anyway.  

  Good Luck . . .

 I'm going to like this guy :)  To add to the too deep / not driven deep enought , a nail gun nail , even if  it is a galv nail or not , is a "smoother" nail shank than a hand driven galv. nail , or it wouldn't /couldn't be co -lerated (sp)/ a gun nail .   Couple that with the "greasing "action of OSB . not sure what cause's that , the glue ? The sealer they put on it (OSB)?  I just know it is a fact , hands on research , lots of it .

I do used nail guns but I pick my places , roofing ain't one of the places .

  Good Luck  :)  PEG
When in doubt , build it stout with something you know about .

Jared Drake

Ok, after reading all this, I'm confused. CDX is plywood, and from what I gather, it's better? Somehow, everything went from 7/16 versus 1/2 to 5/8 plywood. Ok, simple answer for a simple minded guy: 7/16 waferboard (which, I assume, is the same as OSB) is good for roofing and sheathing, right? As long as it's kept dry?
Jared

PEG688

7/16 OSB / Waferboard , I'd say they are the same product , MTL . A by product sheet good made up of chips/ strands , glued together.

 Will it swell if left to the weather , yes no doubt it will.

 It is used for roof sheathing in most areas of the USA , banned in FL. I beleive after hurr. Andrew.  IIRC.  

[highlight]  So simple answer is yes it can and is used for roof sheathing , and should be covered ASAP. [/highlight]

 All the other chatter about what is better , how and why , is just more info, from those who have used it ,    PEG
When in doubt , build it stout with something you know about .

bartholomew

I disagree on the OSB vs Waferboard. OSB has its chips aligned in layers parallel and perpendicular to the long edge. It is quite a bit stronger and stiffer than waferboard when installed with the long edge perpendicular to the rafters/joists. Whichever you get, make sure it is rated as a structural sheathing.


PEG688

#14
QuoteI disagree on the OSB vs Waferboard. OSB has its chips aligned in layers parallel and perpendicular to the long edge.

 quote , 7/16 OSB / Waferboard , I'd say they are the same product , [highlight]MTL [/highlight].

    [highlight]MTL.     More Than Likely[/highlight] . Yes check it out  see if it structural sheathing or not .      MTL  Jared didn't get the nomeclature right , those terms are used loosely , if his package "[highlight]said it was to be used as sheathing" [/highlight]he either tripped the nomclature or he lives in a non conforming  area in which that supplier sells thier product.  


 One might ask what is roof decking ??? Is it a flat roof , that requires a deck and a roof , like this , or  a standard roof , like this ,

 [highlight]You would have to go back to Jareds org post ,[/highlight]

 I'm looking at a home package from Sutherland's lumber and it specifies 7/16" wafer board for the roof decking. What do you think of this? Doesn't wafer board seperate really bad if it gets wet? Also, it doesn't use plywood sheathing, only bracing, asphalt paper and hardboard siding. Is this still a good choice, or is plywood better? Thanks.
Jared
 Context / content , all are subjective if one is not balanced by another [highlight][/highlight].
When in doubt , build it stout with something you know about .

PEG688

The above is sort of why as a builder I love a architect involved . He should drive the spec's for the job , each item joist , rafter , sheathing , roofing is bid apon by each contractor apples to apples . We can talk all day about nothing on this forum if we all sort of do our own thing , would it be apples to apples no , each person would find a way to do it , would all be right ,MTLly no, some would fail either to finish , they would finish poorly and be disappointed in thier failure due to lack of planing , lack of assessing $ and not being able to finish . Failing to factor in time to DIY , etc . The forum is to support all these potentail failure points , to asist and assess all the pitfalls and to rejoice in the accomplishments of said formintes :)

 We have our Arch. on forum he chimes in now and again . There are a few builders here we say some times to much and confuse some folks , by over doing / over loading the capastity to learn .    

For me some times / alot of times your looking for what you say to be confirmed and will ask , sightly changing the ? till you get some one to say ya go for it . If ya think you know , well go for it , and learn the hard way by blowing$$$$
A lot I've learned was just that way it cost me , when I was self employed , or my employer $$ to learn .

  So a Friday night rant , you all have a good weekend , go build something , anything , if your thinking a cabin but it's winter build a storage cab for your  garage , a box is a box it needs to be square ,  AH Carpenter sqr , MTL your cabin / building will be a retangle or a square 90° cornered building , if it's not and it's your first build you can just say that's the way I intended it to be a trapzoide , obtuce angled building , but don't try that round house currently on the first page  ;)  Good luck , PEG    
When in doubt , build it stout with something you know about .

glenn kangiser

That's why I like building with trees, PEG - they grow crooked so I have an excuse. :-/
"Always work from the general to the specific." J. Raabe

Glenn's Underground Cabin  http://countryplans.com/smf/index.php?topic=151.0

Please put your area in your sig line so we can assist with location specific answers.

PEG688

QuoteThat's why I like building with trees, PEG - they grow crooked so I have an excuse. :-/


 How about this structural post?
When in doubt , build it stout with something you know about .

glenn kangiser

"Always work from the general to the specific." J. Raabe

Glenn's Underground Cabin  http://countryplans.com/smf/index.php?topic=151.0

Please put your area in your sig line so we can assist with location specific answers.

glenn kangiser

Now a question about it - obviously it is not graded and stamped - obviously I would use it if I wanted to - obviously it is big enough to replace a 4x4 - will a building official give you a problem with this or does an engineer have to approve it? :-/
"Always work from the general to the specific." J. Raabe

Glenn's Underground Cabin  http://countryplans.com/smf/index.php?topic=151.0

Please put your area in your sig line so we can assist with location specific answers.


PEG688

QuoteNow a question about it - obviously it is not graded and stamped - obviously I would use it if I wanted to - obviously it is big enough to replace a 4x4 - will a building official give you a problem with this or does an engineer have to approve it? :-/


 Don't ask ,don't tell  ;)

 Just kidding  :)  I refurbished the doors in the back ground ,  made a new jamb , reglued those door from pretty much the trash heap . Micro soft money on a San Jaun Island . I wasn't the contractor, just a sub we did cabs and the door restoration , wish I had before pics of those doors , really trashed quite a job to restore them , but $ where everywhere :)

 The post did pass a inspection by the local building dept . I asked the contractor and he said he didn't see a problem , and to my knowledge there was none , problem that is  ;)Peg


 BTW Will this font get bigger, like before we sign in ?  It is much easier to read IMO . Or is it a case of bait and switch ?  ;)
When in doubt , build it stout with something you know about .

glenn kangiser

#21
To make your font larger all the time click your profile button above - modify profile - You will be asked for your password - after that go to the options tab - near the bottom is the use template box-- change it from default to main and save changes - your fonts then will be big like before sign in.

About the post - thanks - that's what I thought -nice job -- once in a while you find inspectors with enough common sense to let something like that pass. :)
"Always work from the general to the specific." J. Raabe

Glenn's Underground Cabin  http://countryplans.com/smf/index.php?topic=151.0

Please put your area in your sig line so we can assist with location specific answers.

glenn kangiser

In fact --extremely nice job, PEG -- those doors are beauties -- they look like one or only a few of a kind at least.
"Always work from the general to the specific." J. Raabe

Glenn's Underground Cabin  http://countryplans.com/smf/index.php?topic=151.0

Please put your area in your sig line so we can assist with location specific answers.

PEG688

Thanks Glenn  :) I think I got it still in the send typing mode the font is back to like before,  Preview is larger.   8-) 8-) Thanks again , PEG
When in doubt , build it stout with something you know about .

PEG688

QuoteIn fact --extremely nice job, PEG -- those doors are beauties -- they look like one or only a few of a kind at least.


 The only two like that I've ever seen . Well worth the $ to the client as they came out  of a old famliy glass business in the Seattle area IIRC. The client had passed thur them many times as a kid , they where very pleased , to say the least :) Some times I love being a carpenter/ builder / cabinetmaker / luther / furniture maker.   Well I have repaired one guitar , so I'm a sudo luther :-[PEG
When in doubt , build it stout with something you know about .