OSB vs. Plywood. Please proof this new inspection article.

[Nick Gromicko]

http://www.nachi.org/osb-plywood.htm

[Joe Funderburk, CMI]

Excellent.

Nick, can we copy/paste this text to our websites, or just use a link to it?

[Mark S. Tyson]

Originally Posted by gromicko

http://www.nachi.org/osb-plywood.htm

well written, well researched, well done. as a general note i would add that osb is technically more difficult to insall as it is imparitive that the 1/8" edge disance be maintained between panels where plywood is much more forgiving on that spacing. also osb is manufacured with a sealer applied to the edges to help prevent water intrusion and swelling.works great until you have to cut the panel to install it at windows, doors etc.

[Joe Funderburk, CMI]

If you live in the Detroit area, neither will stop bullets.

[Nick Gromicko]

Joe asks:

Excellent.

Nick, can we copy/paste this text to our websites, or just use a link to it?

They are yours to use as you like. They are search engine optimized to help your website ranking, so if I were you, I'd re-build (copy & paste) them into new pages on your inspection business website.

More being added here: www.nachi.org/articles.htm every week.

[Michael Roberson]

Sub note to this article: I have seen plywood De-laminate when installed on roofs, in extreme heat situations. Anyone else confirm that?

[Mark S. Tyson]

Originally Posted by mroberson

Sub note to this article: I have seen plywood De-laminate when installed on roofs, in extreme heat situations. Anyone else confirm that?

absolutey especilly here in south florida where we get rain storms daily during the summer rainey seson. generally those delaminations are replaced by order of the building department during the roof sheathing inspection and of course they walk all of the 2 story roofs with 6/12 pitch. lol

[dbelmont]

Nice piece. Got one quibble.

This last line

"In summary, OSB and plywood, while used for the same purposes, perform somewhat differently."

While I agree and the piece points out some of the quirks of the different materials if you're talking about similarly rated sheet goods they are effectively interchangeable. So it's not the performance that is dissimilar, it's how to properly install and utilize IMO.

[dbelmont]

Originally Posted by mroberson

Sub note to this article: I have seen plywood De-laminate when installed on roofs, in extreme heat situations. Anyone else confirm that?

Yes. Usually when the materail has been allowed to get wet/stay wet beyond it's rated exposure. Throw in some high heat and things can start coming unglued. I don't think it's the heat as much as it's the wet but I could be wrong.

[Jeffery L. Haynes]

While informative Nick, I think it could be misleading to those who have never actually worked with either type of product; some of the information you have provided is not factual or at best, broadly stated.

For example, plywood will delaminate (as one of the others pointed out) and it does
swell just as much as standard OSB without returning to to its original size......(I have cut plenty of it out).....or at best it takes along time for it to return to a reasonable thickness....framers and subs behind them are not going to always wait for this to occur.

Also, there are many reasons tile crack..much of it to do with floor deflection....that is not necessarily attributed to one type of sheating over the other.....there are many factors involved.....to say that plywood is a better sheathing for tile is not correct............besides, tile should never be installed directly over osb or plywood......but that is for another topic.

I have installed thousands (if not tens of thousands) of both.......much of it has to do with the manufacturer. AdvanTech flooring is by far the best product I have ever used, I still use it today ....(I will not stand behind any other product and I put same in writing) have been using it for a long time......and while I have tried other products at the behest of manufacturer reps I meet through my lumber supplier, everyone from Plytanium to Edge Gold are all inferior. I have had Advantech sitting in 1 1/2 inches water for a week (sole plates not cut out).............not one swelled edge......there is no plywood on the market that can do that........none.......Advantech by far is the strongest product out there.

As to floor squeeks.....much of that is due to improper installation including type of nails used as well as not using flooring adhesives.

Most framers are simply nailing 90 degrees to the sheathing and they often do not have the pressure properly adjusted for the sheathing they are nailing nor taking into consideration the type of joist they are fastening.........certain I-joist are denser than your traditional lumber which means you have to account for that when nailing the sheathing. Squeeks should not be attributed to one type of sheathing versus the other......its an installation issue.

OSB got a bad name in the late 70's early 80's when it first came out.......the glues were substandard with corners and edges often breaking........however during the last 20 years they have come along way....especially the last 10.

One should be careful in thinking that all OSB's are the same......they are not.

Before going to press on this one I would consider rewording the whole thing in a manner that truly takes into consideration the differences in the manufacturer products themselves other wise this article is truly misleading which can be problematic for an inspector (and client) who truly is not informed of the true difference not only in OSB vs. Plywood but the types of OSB offered.



best regards

Jeff Haynes

[Michael Roberson]

AdvanTech flooring is by far the best product I have ever used, I still use it today ....(I will not stand behind any other product and I put same in writing)

Jeff, I agree with you, I love the stuff, but havnt used as much as you. It is an OSB product, but can you really call it OSB? more like a cousin.

[Jeffery L. Haynes]

Its is OSB but from what I see the secret is in the resin / glues that they use. I remember in the late 70's and early 80's when I was framing a home every 3 - 4 days with regular osb...... I absolutely hated OSB back then......however it has come along ways.....and Advantech is light years ahead of the competition.

The last large spec home I built I installed Edge Gold on the 1st floor and Advantech on the 2nd floor where the floor was hammered with rain.....the Advantech did not swell one bit......the plywood did and I had to end up sanding all the edges prior to installing hardwood.......so to say that plywood will go back to its original state is not quite true.......especiallly with a crawlspace where moisture levels are elevated anyway.

I am not trying to tear the article apart however it is not correct and is somewhat misleading......at least in my mind.............I came away reading that it appears that plywood is better when it clearly is not..... at least compared to Advantech.

And as I stated earlier.....many of the complaints from either product are installation issues or not taking into consideration the final floor product, ie. installing tile over a floor system that is 24 inches on center is crazy...unless you put a 7/8 inch product such as Advantech for such applications......which I have at times.....talk about heavy....that stuff weigh about 100 pound per sheet.........but it is very sturdy.

regards

Jeff

[Rob London]

Jeff,

I added the following to the end:

Note - much of the information above that favors plywood over OSB is summarized from a study by Georgia-Pacific, a building materials manufacturer. While Georgia-Pacific manufactures both materials and thus has no obvious bias, the study does not state whether it compared multiple brands of OSB and plywood or merely their own.


A problem I ran into while researching this is that for almost every "fact" I found saying OSB was better than plywood I would find that same exact "fact" being used the other way around. (OSB holds nails better vs. plywood holds nails better, OSB swells more vs. plywood swells more). I could only find one formal study from an apparently unbiased source, and that is what I trusted to write this.


Also, I added something about plywood potentially delaminating in hot weather.


cheers

[Jeffery L. Haynes]

I understand that it can be problematic as to finding reliable sources however I just wanted to point out that the quality of OSB varies significantly from manufacturer....especially AdvanTech.......... and that most problems originate with installation as well as flooring design issues.

I would take issue that simply because GP manufacturers both products that they are unbias........they may be unbias about their products but when comparing GP's osb's and plywood to JM Huber, it is night and day. (that comes from 30 years of working with both types of products in the field)

You may want to consider stating that "certain manufacturers products exceed others in design and quality; it would be wise for interested parties to do their own research as to what would best meet their needs and/or consult with a licensed engineer
familiar with the noted products."

(2x4 floor trusses at 24 inches are center with slate or tile on same would be better served with a 7/8 inch AdvanTech OSB due to span and strength ratings etc )

Food for thought.


regards

Jeff Haynes