Can anyone point me to literature on why gapping OSB is necessary and maybe photos of OSB that was not correctly gapped. I have a few employees that believe that they know better than I and want to push them tight together when the boss is not around.
thx
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Hmmmm...good question? Does OSB actually indicate on the panel that it must be gapped? I don't know as I never use OSB for sheathing, just ply which indeed does have the stamp that says it must be.
Is OSB stamped right on it like ply is?
Ever measure your OSB? Weyerhauser's stuff is just shy of 48" wide but it's exactly 96" long, which means that it works fine to gap it out on the long edges - usually makes no difference there anyway - but if your structure is more than 24' long you need to trim the sheet to length every 3rd one or so in order to maintain truss or stud spacing. I'll admit to not doing that all the time although I do space them the long way. My stuff is all marked with instructions to space it 1/8 between sheets. I use a 8d nail. H-clips for osb have little bumps on them to space it out, h-clips for plywood are flat. j
Expansion, creaking, angry homeowners. I dont have any literature, but these are some of the reasons to gap.
Family.....They're always there when they need you.
"ECAH" should be stamped on the panels! :) (expansion, contraction, angry homeowners)
I like that...
"creaking, angry homeowners."Man, they're the worst!AitchKay
You should be able to download installation instructions from the manufacturer. Most sheets are clearly stamped, "sized for spacing". With many building materials, installers should read the instructions. If they aren't followed, you don't have any warranty. An employee would get a warning or two before they were no longer an employee.
Walls usually aren't subject to much weather. Roofs can be another matter. You not only have exposure during construction but conditions in the attic can cause expansion of the OSB. This can transfer to a visible bump in the roofing. The same thing can happen if roofing shingles are kept too tight to each other. You can expect a homeowner to have something to say about this situation and they aren't going to call your employee, are they. H-clips are often used on roofs, they hold the spacing on the long edges. A spacing jig of some type makes keeping things in line much easier. Without one, the sheets can get whacky. Some just use the blade on their combo square, others have something made up.
In the early days of OSB it didn't like water at all. Most products are minimally effected today, but there are many brands, some may not. be so great. An ounce of prevention....
Beat it to fit / Paint it to match
http://www.hammerzone.com/archives/flooring/hardwood/prep1/subfloor.htm
He has pictures and experience in the article.
Tu stultus es
Rebuilding my home in Cypress, CA
Also a CRX fanatic!
Look, just send me to my drawer. This whole talking-to-you thing is like double punishment.
A similar question once here at BT brought out a couple photos and stories by guys who had learned the hard way. One guy said he'd been butting tight for years on a hundred houses or so, but finally one place had enough moisture swell the osb to buckle the sheets and he had to strip it and re-roof.
mostly the swelling is only minor enough to telegraph the sheet positions and edges through cheaper three tab shingles.
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Why gap OSB???
Oh Man, can I tell you. Back of a 6 bay garage, framed and sheathed with the OSB jammed tight, not occupied or insulated space so no Typar. This was done during an 8 week dry stretch. Then a week of rain and the siders show up and proceed to hang 10 squares of Hardie plank on it. Go and look at the back and I've seen oceans with less waves. Right in the middle of each sheet there's a big hump. Rip off the Hardie, 2 saw kerfs at each seam, wait 3 weeks and pray for no rain so it all dries out. Put up new Hardie and shim the #### out of it and now it looks half way decent. Long story short, ALWAYS gap your OSB.
You've got that right!! I can tell many horror stories about OSB not being gapped and seeing that happen.
Watch it happen on a wall with 24" stud spacings!!
Plywood, too, needs to be spaced 1/8". Always used sheets "sized for spacing".
The primary difference between the moisture-swelling of OSB and plywood is that plywood will return to its original dimensions, OSB will not. Also OSB, as well all know, swells in thickness at the edges. It absorbs more moisture because there is far more exposed endgrain from the chips. This sometimes results in a roughened surface.
APA recommends spacing all sheetstock 1/8" at both long and short edges (a 10d box nail is perfect as a guide)
Some OSB manufacturers won't warrentee their product used as roof sheathing on an unvented roof, because while OSB is slower to absorb moisture than plywood it's also slower to release it and the aspen and poplar used has no resistance to decay. If used on a roof and exposed at all to the weather, OSB cut edges should be field sealed.
Riversong HouseWright
Design * * Build * * Renovate * * ConsultSolar & Super-Insulated Healthy Homes
Edited 1/24/2009 1:39 am ET by Riversong
Edited 1/24/2009 1:39 am ET by Riversong
If a product is meant to have a space, then it should be reflected in the sizing of the product.
If the OSB comes 8', you had better not space, it will destroy your layout!
Thank you so much frammer 52. I cannot imagine a better lawsuit waiting to happen than stamping sheet goods as requiring spacing, then producing them at a dimension that makes that spacing impossible with standard layout practice. I guess they have their own out, though : "hey, your sheets buckeled - guess you didn't gap them", instead of" Hey, your sheets buckled - maybe our product is vulnerable to some issues." Maybe lumber yards should start cutting studs at 92 1/2" so we can all be busy cutting that extra 1/4" off, too.
Maybe lumber yards should start cutting studs at 92 1/2" so we can all be busy cutting that extra 1/4"
Don't understand(my precuts are 92 5/8)
It's a regional thing. Out west they are 92 1/4". Don't know why but they've been that way since I started in 1970 +/-. Don't know where Born2hammer is from.John
Edited 1/25/2009 11:29 am ET by JohnCujie
Hi frammer 52,
I'm from northern California. Spelled a lot like Carolina, and also coastal, but I guess we are worlds apart when it comes to our respective lumberyards. Before 9' and 10' ceilings got so popular (ridiculous, if you ask me) the only precut stud measurement to be found out here was 92 1/4". No wonder you didn't understand me.
Here's how a journeyman explained it to me way back in 1977 when I was a young apprentice: 92 1/4" + 4 1/2" (one bottom plate and two top plates) = 96 3/4"
1/2" or 5/8" sheet rock lid goes up against the ceiling joists, that leaves 96 1/4" or 96 1/8" for sheet rock on the walls (vertically or horizontally).
Want to know where the habit of doing 16" on center layout came from?
Want to know where the habit of doing 16" on center layout came from?
Yep.
94969.19 In the beginning there was Breaktime...
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"Maybe lumber yards should start cutting studs at 92 1/2" so we can all be busy cutting that extra 1/4" off, too."
Let me guess, you're from the Carolinas, right? I always thought an 8' precut was 92-5/8", then I went school in SC and the precuts were short.
Wait a minute, the precuts in SC were 93". Now I'm really confused.
So, where are you from? And can anybody in SC confirm the precuts are 93". I'm all mixed up.
Jon Blakemore RappahannockINC.com Fredericksburg, VA
Hi JonBlakemore
Whoops, a lot of my response above to frammer had answers to your questions - sorry. b2h
But in spite of being stamped "sized for spacing" when I put a tape to it, most of the OSB we get is a full 96" by 48". Maybe we're sposed to frame on 16.02" centers! Otherwise you get that irritating layout creep.
You're right...the stuff is already swelled up to full size when you get it. But...If you don't space it, you are going to have trouble with buckling walls if it gets wet.
I find it easier sometimes to just cut a kerf between sheets after it is installed.
It doesn't have anything to do with swelling. I've used it literally hot of the press and it measures the same.
I use cdx fir and space the walls. It's code where I'm from. I've never once spaced the sheathing on a roof before and never once had a problem. All this BS with OSB makes me wonder why people keep using it and not installing it right, or when installing it right you still have problems.
Joe Carola
Joe, never had a problem with swelling in the last 10-15 years. Fir is nice, but the home builders don't want to pay for it!
Joe, never had a problem with swelling in the last 10-15 years. Fir is nice, but the home builders don't want to pay for it!
I've used osb a few times on walls, never once on a roof. I've never had a problem not spacing the fir sheathing on a roof in 25 years. All we use is fir around here. I do see osb on some developments, but people who I work for use fir. When I have a say in what material to use, I use fir also.
Joe Carola
With OSB at about 6 bucks a sheet, why would I use fir? I've never personally had a problem with OSB. Never. The only sheathing problem I've ever had was delaminating plywood. That happened to me once on a wall that didn't get stood up at the end of the day, and a few times on floor plywood. Never had a problem with OSB.
All........... If you are going to space 1/8in on a 96in osb roof sheating how do you lay out 60 ft of truss's to compsate for that mutipling 1/8 in?
For years now I have gone back after the roof is sheeted and used a thin kerf blade and cut the butt joints of the osb.
The butt joints are really obivious on early morning frosts in my area of centeral Illinois
I've never had a problem not spacing the fir sheathing on a roof in 25 years. All we use is fir around here
Never said you did, and it is nice to use fir as it is lighter, alass that is not in the cards.
I thought you had specialty sheathing crews for that, or am I remembering somebody else?Better save those pins from your fingers and start using them as specialty spacers, LOL
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I thought you had specialty sheathing crews for that, or am I remembering somebody else?
We do. I just use them on houses.Many times I've sheathed houses also. All the additions I do, I sheath myself. They just gap the walls, no roofs.
Better save those pins from your fingers and start using them as specialty spacers, LOL
I was supposed to save one, but forgot.
Joe Carola
There is no swelling in the OSB on the market now, except on cut ends if you don't cover.
You are stuck in the 80's, wake up!
You must be kidding!!! Why do you think they stamp the spacing info all over the stuff?
If you've got OSB (or plywood) that doesn't swell, you are in the minority!
I use nothing but Advantech on the floors. That's great stuff. Anything else swells. At least around here it does! Our OSB is made with aspen, which sucks up water like a sponge. Plywood is much worse than OSB in my opinion.
As stated in APA literature: 1/8 inch spacing is recommended at all panel edge and end joints (subfloor, wall and roof) unless otherwise indicated by the manufacturer. Spacing is an APA recommendation intended to minimize the risk of panel buckling when panels are exposed to moisture during construction or acclimatize to a higher moisture content after installation.
Edited 1/24/2009 8:06 pm ET by BoJangles
You must be kidding!!! Why do you think they stamp the spacing info all over the stuff?
No, I'm not kidding. Like I said before, on roof sheathing I don't space anything. I don't space decking either. I just space the wall sheathing with a nail between each row running the sheats horizontally. I've done it like this for 25 years. Why would I not tell the truth.
If you've got OSB (or plywood) that doesn't swell, you are in the minority!
I guess I'm in the minority.
Plywood is much worse than OSB in my opinion.
Not for me. From what I read hear and other forums, osb seems to be the one that everyone complains about
Joe Carola
Why do you think they stamp the spacing info all over the stuff?Had to go look and see if you are correct,NOT!
you've got OSB (or plywood) that doesn't swell, you are in the minority
Doesn't swell if you get it covered. All OSB has a coating to prevent. Inless it is a cut end, it soesn't swell as long as it is covered in a normal time on a job. Tyvek or felt and does't swell.
Plywood in my experience will swell faster than OSB in todays market. Advantek is great stuff, I agree.
"Doesn't swell if you get it covered."A lot of the reported cases of swelling and failure are on garages where the moisture gets to it from the underside.
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
Paul, I must live in a special area of the country, we just don't see it around here!
Maybe what you get is "pre-swelled";)
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
Funny! maybe why the 1/2" is 3/4?
what do U need pictures for, just fire them for not doing what ya tell them to do.
Jeff
Buck Construction
Artistry In Carpentry
Pittsburgh Pa
One should always follow manufactures directions which i never read on general principle, I much rather like to find out the hard way.
I did not gap and it bit me, But i did find when the cut ends were not gapped they swelled but the painted ones never did
Don't you love supervising people? It used to get me that every sheet was stamped "space panels 1/8" at the edges" or something like that, and I'd tell the guys to do it and they'd look at me like I was from Mars. Seems like carpenters are taught that a tight fit is ALWAYS better, even if it buried beneath 40 year shingles. And they also must have been taught to always ignore written instructions.
I haven't been burned by it myself, but I used to drive by a cheap housing development where if the sun was right, you could see every sheet outlined through the shingles. That development was built during a very rainy summer.
Edited 1/23/2009 6:56 am ET by Marson
most of the roof problems are probably 1/2 sheeting and 24" center issues ...
"most of the roof problems are probably 1/2 sheeting and 24" center issues ..."Not sure why that would lead to the sheets being outlined. Sagging between trusses yes.
good and simple reason, I am the boss, you don't gap the osb, I don't sign your paycheck. And when you get to be the boss, you can do the same.
There was an article a few issues back in JLC showing framing mistakes One of the probs was some OSB on a wall that had been installed tight then buckled.
Have a good day
Cliffy
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Jeff and Cameraman had the answers I liked the best. Like the old "because I said so" you got as a kid from your Mom. If you want to educate them we all know that building materials expand and shrink to different degrees simply from heat and cold. Not moisture. Make up a little demo showing size change using a balloon with hot air (oh, thats what make those balloons expand and go up, up and away!).
Paychecks can expand or contract too.
Years ago a mining process company did its research for a client and the client got a report the equivelent to penciled info on a legal pad in the mail. Looked like ####. I was asked to improve on it. They got an organized report with a cover sheet printed with company logo, address, phone, all the research data in tables, graphics showing how the process was done, and a conclusion signed by researchers, the president, etc.
That was the only thing a client saw from the company. That report "was" the company to them. They came back and spent more even if the first research showed their first try wasn't feasable. Like drilling a dry hole for oil or NOT striking a rich gold vein.
If those guys don't like your standards I think there are more than a few looking for work right now that will. Who runs the show? Sells a second job if the first looks good? As John Wayne said in his last movie, "Mr. you better find another line of work because this one sure don't fit your pistol" Tyr