OSB vs Exterior plywood
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Category: General Correct Craft Discussion
Forum Name: General Discussion
Forum Discription: Anything Correct Craft
URL: http://www.CorrectCraftFan.com/forum/forum_posts.asp?TID=25890
Printed Date: April-29-2024 at 4:09am
Topic: OSB vs Exterior plywood
Posted By: john b
Subject: OSB vs Exterior plywood
Date Posted: May-07-2012 at 5:31pm
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I have a very strong opinion about the suitability of OSB for use where there is the potential for exposure to moisture. I have an example here. About five years ago I built sides for my utility trailer out of 1/2" exterior plywood. While not ideal because of the voids. it was not made to be particularly long lasting or visually pleasing. Two years ago when I was hauling some stuff to the landfill I needed a cover for the trailer. Being that I had a sheet of 1/2" OSB that I had no use for, I fashioned a top from it. Here is the result. Remember, the sides are about 5 years old and the top is 2. Both have been exposed to the same conditions as they are used together and stored outside. Here is the trailer, a Triton single place torsion axle snowmobile trailer.  Here is a close up of the edge of the OSB top after a 726 mile round trip to the cottage and back two weeks ago. Note that with the de-lamination from the elements, it suffered wind damage  The other leading edge corner.  The top surface.  And here is an example of what a void will do to plywood. This is why I always use marine plywood. It is made from Douglas Fir, and has no voids.  Any questions? ------------- 1970 Mustang "Theseus' paradox" If everyone else is doing it, you're too late! |
Replies:
Posted By: JoeinNY
Date Posted: May-07-2012 at 6:04pm
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No offense to either of the two partisans but IMHO Waferboard has no legitimate use in any boat, whether it has been covered, coated, cpes injected under heat and pressure, or otherwise.. Coosa has no business being in a wooden boat.. and yes it can get wet- that is why it bonds well to resin, no it can’t absorb any appreciable amount of water.. if you aren’t going to cover it with glass it would be worth giving it the quickest of brushes with resin if it can contact something you don’t want it to transfer wetness to.. Marine plywood is generally, but not always a waste of money as compared to exterior grade plywood for uses such as a covered floor, or any glassed component. In my experience anyone putting down a floor in either wood or fiberglass boats that will be wrapped in vinyl or carpet and screwed down to the subfloor should simply get some pressure treated plywood and just let it dry in the sun for a bit before gluing on the flooring. It will easily outlast the flooring material without additional treatment and generally costs less than exterior grade with cpes, or marine plywood alone. This is not the same as creating a stringer/floor system to replace the foamed/glassed floor that is directly carpeted on later model boats… those floors should be made of resin friendly materials and should primarily be held in place by direct bonding to the stringers and floor supports. ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=1477 - 1983 Ski Nautique 2001 1967 Mustang 302 "Decoy" http://www.youtube.com/watch?v=cO5MkcBXBBs - Holeshot Video |
Posted By: HatterBee
Date Posted: May-07-2012 at 6:12pm
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Well said Joe...The cost difference is just not worth it, especially if you are going to wrap it with glass. ------------- 1977 Ski Nautique Under Re-construction http://www.correctcraftfan.com/forum/forum_posts.asp?TID=25004&title=1977-ski-nautique-rebuild" rel="nofollow - My Rebuild Thread |
Posted By: TRBenj
Date Posted: May-07-2012 at 6:27pm
The floor in my http://correctcraftfan.com/diaries/details.asp?ID=3024" rel="nofollow - junk Skier was made of OSB when I got it. At least thats my best guess. It was a *little* tricky to identify. But thats what some of the chunks looked like that had fallen into the bilge. I would rate it pretty far down on the structural scale though... the only thing holding the floor together was the foam underneath and the carpet above (where applicable- note the hole). ------------- |
Posted By: juniorwoody
Date Posted: May-07-2012 at 6:36pm
I agree with this man right here! |
JoeinNY wrote:Posted By: 8122pbrainard
Date Posted: May-07-2012 at 7:14pm
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John, You forgot to CPES and put a layer of glass on all the sides of that top you made for your trailer!  BTW, that's not OSB but as Joe mentioned incorrectly is waferboard! ------------- /diaries/details.asp?ID=1622" rel="nofollow - 54 Atom /diaries/details.asp?ID=2179" rel="nofollow - 77 Tique 64 X55 Dunphy Keep it original, Pete < |
Posted By: TRBenj
Date Posted: May-07-2012 at 7:21pm
Pete, according to http://osbguide.tecotested.com/pdfs/en/tb103.pdf" rel="nofollow - this bulletin the only difference between OSB and waferboard is the orientation of the grain. While that clearly makes a difference in how strong it is in any given direction, I fail to see how OSB will better survive in a marine environment. Isnt that what we were talking about? ------------- |
Posted By: john b
Date Posted: May-07-2012 at 7:39pm
That is true, Pete. It is Potlatch OXBoard. Only the lack of orientation is different. I also failed to CPES the sides and they have held up well, except for where the voids have held water.I can't imagine doing a restoration and using a product such ad this to save the price of a case of beer or a 1/4 tank of gas. ------------- 1970 Mustang "Theseus' paradox" If everyone else is doing it, you're too late! |
Posted By: Hussler
Date Posted: May-07-2012 at 7:49pm
That is exactly what I plan on doing for my floor  I will be making the entire floor removable. |
Posted By: john b
Date Posted: May-07-2012 at 7:50pm
Moving right along, here is my last project from 6 years ago. It's my 1964 Mark Twain that I am replacing with the Mustang. When I bought it it needed a total restoration, which I did. Here is the floor when I got it. It was made with an engineered wood product. a beautiful sight to behold in the hold. It was only held together by the glass shell on top. Luckily the boat had hollow core fiberglass stringers so it was just a case of cleaning it up and screwing down a new marine plywood floor treated with CPES. It is much better now!      ------------- 1970 Mustang "Theseus' paradox" If everyone else is doing it, you're too late! |
Posted By: 8122pbrainard
Date Posted: May-07-2012 at 8:09pm
Yup, that bulletin pretty much explains it just like I have.
It just like ply needs to be sealed. John, Yes, for the price of that beer or gas, The cost difference isn't much but it's still a difference. Someone on a real tight budget might be interested. ------------- /diaries/details.asp?ID=1622" rel="nofollow - 54 Atom /diaries/details.asp?ID=2179" rel="nofollow - 77 Tique 64 X55 Dunphy Keep it original, Pete < |
Posted By: Hussler
Date Posted: May-07-2012 at 8:43pm
Shirley, you can't be serious? |
Posted By: 65 'cuda
Date Posted: May-07-2012 at 9:04pm
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OSB, Waferboard, whatever, it has two things going for it, Its cheap, and it sucks, sucks up moisture. It is not: Strong, stiff, tough, resilient, or long lasting. It does not hold fasteners, adhesives, or coatings. I could literally kick and claw my way through a sheet of it, try that with a sheet of plywood. I hate using it for it's intended purpose. Do not put any of in a boat for any reason! ------------- Gary http://www.correctcraftfan.com/diaries/details.asp?ID=941" rel="nofollow - 1965 Barracuda SS |
Posted By: Riley
Date Posted: May-07-2012 at 9:07pm
| OSB has become standard wall and roof sheathing in typical, average new construction, but high end homes are still specd out with plywood for some reason. Pete, where did you hear about using OSB for marine use? |
Posted By: 8122pbrainard
Date Posted: May-07-2012 at 9:40pm
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Bruce, I haven't heard about OSB for marine use. I also haven't ever heard about LVL for marine use but it is used. Both are engineered wood products. These high end homes you referred to, they don't use any engineered products like "I" joists or LVL headers? No LSL or PSL for columns and beams? How about OSL for rim boards? ------------- /diaries/details.asp?ID=1622" rel="nofollow - 54 Atom /diaries/details.asp?ID=2179" rel="nofollow - 77 Tique 64 X55 Dunphy Keep it original, Pete < |
Posted By: Riley
Date Posted: May-07-2012 at 11:08pm
| Pete, didn't say no engineered products. Just not OSB for exterior sheathing despite its much lower price compared to CDX. High end homes tend to use a lot of engineered products, but not OSB for the exterior sheathing. |
Posted By: baitkiller
Date Posted: May-07-2012 at 11:21pm
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I reckon y'all should read this: For the record I have known Hugh for many many years. I last saw this boat when it was just framed from scanltings>up. http://www.saintcustomboats.com/MissOSB.html ------------- Jesus was a bare-footer............. |
Posted By: peter1234
Date Posted: May-07-2012 at 11:30pm
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dont forget advantec what is that stuff penetrated with? it does make good underlayment but if it gets soaked befor the roof goes on even that product swells.. Pete a tight budget? come on now you are grasping at straws.. ------------- former skylark owner now a formula but I cant let this place go |
Posted By: Hussler
Date Posted: May-07-2012 at 11:34pm
Actually due to the burn rate of wafer board and OSB they are usually avoided in more expensive homes. Especially Engineered I beams. My local fire department sent out a letter requesting that they to inspect homes that were built with engineered I's, they burn out in the middle and the building collapses very quickly. |
Posted By: fanofccfan
Date Posted: May-07-2012 at 11:48pm
| Oh Pete. Feelin' for ya on this one. Very interesting thread though. |
Posted By: juniorwoody
Date Posted: May-07-2012 at 11:56pm
| I have been told that I haven't been around very long so I should do a little reading up but I know cabbage when I see it and that is all that OSB is worth to a shipwright. I feel somewhat vindicated as I read this thread.I guess it's going to be hard to get anyone to admit that they used it at this point. Those that hardily defend it seem quite suspect. Just looking for a followup on long term performance. |
Posted By: 8122pbrainard
Date Posted: May-08-2012 at 10:15am
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http://www.saintcustomboats.com/MissOSB.html%20" rel="nofollow - Miss OSB - I like it! ------------- /diaries/details.asp?ID=1622" rel="nofollow - 54 Atom /diaries/details.asp?ID=2179" rel="nofollow - 77 Tique 64 X55 Dunphy Keep it original, Pete < |
Posted By: peter1234
Date Posted: May-08-2012 at 10:47am
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you never know who owns stock in what company....... ------------- former skylark owner now a formula but I cant let this place go |
Posted By: OverMyHead
Date Posted: May-08-2012 at 11:11am
Cool boat, but if the guy did not have "stock" in the company would he have made other choices? I am bettig the boat builder has not used it since. Plywood is an engineered product also. Nothing wrong with engineered. LVL is far superior for a header/beam than a standard joist. the question is the superiority of plywood or OSB near water. ------------- For thousands of years men have felt the irresistible urge to go to sea, and many of them died. Things got better after they invented boats. 1987 Ski Nautique |
Posted By: juniorwoody
Date Posted: May-08-2012 at 11:40am
| Miss OSB is certainly a good looker and must have been a real challenge to build. She is not however a good example of OSB use in boat construction. Missing in the presentation is the fact that the owner an OSB manufacturer, used a special blend in the formula that included more resins. You can't buy the stuff. This special blend also rendered the boat very heavy. Lets try to give good useable advice on this forum. In a pissing contest nobody becomes a winner. |
Posted By: 8122pbrainard
Date Posted: May-08-2012 at 11:48am
Jack, I wondering where you picked up this information? Any documentation? ------------- /diaries/details.asp?ID=1622" rel="nofollow - 54 Atom /diaries/details.asp?ID=2179" rel="nofollow - 77 Tique 64 X55 Dunphy Keep it original, Pete < |
Posted By: JoeinNY
Date Posted: May-08-2012 at 12:06pm
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It is right on the website in the article text ... ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=1477 - 1983 Ski Nautique 2001 1967 Mustang 302 "Decoy" http://www.youtube.com/watch?v=cO5MkcBXBBs - Holeshot Video |
Posted By: 8122pbrainard
Date Posted: May-08-2012 at 12:17pm
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Joe, All I found in the text is this statement: "the oriented strand board used was special in that it was made of hardwood chips and waterproof resin." Am I missing something about "a special blend in the formula that included more resins"? ------------- /diaries/details.asp?ID=1622" rel="nofollow - 54 Atom /diaries/details.asp?ID=2179" rel="nofollow - 77 Tique 64 X55 Dunphy Keep it original, Pete < |
Posted By: Riley
Date Posted: May-08-2012 at 12:25pm
Very interesting boat, but hardly evidence that OSB is appropriate for marine use when the owner of an OSB plant has a boat custom built to use his own product. How much you think he saved using OSB? You can't argue with a guy that thinks he's got three legs. 
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Posted By: juniorwoody
Date Posted: May-08-2012 at 12:32pm
| I followed a ink on the topic in Boat Design.Net. Can't seem to find it now. You might want to read also Guideoun(sp)Bros chapter 5 and what they say about OSB use in the boat building industry. You can make a barn door fly with a large enough airplane engine on it also. |
Posted By: OverMyHead
Date Posted: May-08-2012 at 1:19pm
I would say Miss OSB is all that and a bag of chips. All that now, and a bag of chips in fourty years. I can imagine how much fun it would be to try and dissasemble and pattern.  ------------- For thousands of years men have felt the irresistible urge to go to sea, and many of them died. Things got better after they invented boats. 1987 Ski Nautique |
Posted By: must_dash
Date Posted: May-09-2012 at 4:48am
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It may be OSB, but look at the spec. The OSB is hardwood chips in WEST resin. Not the stuff we can go and buy. It's probably better quality than the marine ply we buy. ------------- 1986 Martinique - sold When we ask for advice, we are usually looking for an accomplice. |
Posted By: 8122pbrainard
Date Posted: May-09-2012 at 10:13am
Tom, Yes, the OSB was encapsulated in epoxy but per the article, it was done after the OSB was made using traditional resins. Getting epoxy through a OSB manufacturing line would be a big problem. The use of "hardwood" chips of flakes I'm sure was done for color and not strength. There are many soft woods like Sitka Spruce or even Doug fir that are higher in tensile than many hardwoods like some Mahogany's. ------------- /diaries/details.asp?ID=1622" rel="nofollow - 54 Atom /diaries/details.asp?ID=2179" rel="nofollow - 77 Tique 64 X55 Dunphy Keep it original, Pete < |
Posted By: 8122pbrainard
Date Posted: May-09-2012 at 10:23am
Jack, I forgot to pull out my Gougeon book yesterday when I got home yesterday. Hopefully, I can find it - I haven't used it since the days when everyone was finding out that the West system bottoms were failing. I'll look for it today. ------------- /diaries/details.asp?ID=1622" rel="nofollow - 54 Atom /diaries/details.asp?ID=2179" rel="nofollow - 77 Tique 64 X55 Dunphy Keep it original, Pete < |
Posted By: juniorwoody
Date Posted: May-09-2012 at 1:04pm
| Thinking this topic has been pretty well pulverized. |