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Ok this will probably be a dumb question in hindsight, but…
I know that one is supposed to leave 1/8″ spaces between subfloor sheets for expansion. I also know that one should use T&G to avoid blocking on joints perpendicular to the joists. But one can’t both use T&G and leave spacing. Doesn’t seem to make sense to leave spacing only on the short side of the sheet.
I feel like one of those computers that Captain Kirk made go boom by posing puzzles like this.
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Replies
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Hi Roger,
I don't know of anyone that would leave 1/8 inch spacing on t&g plywood. Afer 4 sheets you would be off the joist with the edge. We glue and screw those suckers down and always with a snug fit.
Gabe
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Well, yes, but this is my point exactly. No-one leaves a space with T&G, but what about all the words that have been written in this forum regarding the need to leave spacing in case of rain-caused swelling, which without spacing would require sanding at the joints to re-level the surface. (I recall one person mentioning doing this with a drum sander and 20 grit paper)
Come to think of it, spacing sheets whether on T&G or not would eventually result in the joint wandering off the joist. Are OSB sheets sized down 1/8"?
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get real... the t&g is on the long edge..
the short edge is square and you still leave a 1/8 inch gap for good practise...
the sheets do end up short.... on a 28 foot house you will lose about two inches which youhave to make p with a filler
so use the t&g.... but don't jamb them.... they should be snug , but not jammed...
b but hey, whadda i no ?
*And Roger, space or not, reg. osb will swell at the t&g if rained on enough. Buy the best or the one with the waterways in the tongue or plain old osb. Sand them all if necessary. Or work like hell and get it under roof asap. This home building is a battle. Hope you win.
*Roger,
View Image © 1999-2000"By the time a man realizes that maybe his father was right, he usually has a son who thinks he's wrong." Charles Wadsworth
*hey fuscoe.... read the instructions stamped on every sheet.....duhPogo
*I would especially recommend you leave the 1/8" space on the 4' end of the panel. The panel will expand over its entire length with moisture absorbtion. I also leave the T&G joint slightly loose (1/16" or so). I'm not counting on drainage paths for my sheathing (that is the job of the roofing and siding), just allowing room for the expansion that will occur as it's moisture content changes.And yes, the sheathing is manufactured an 1/8" short on its' length.
*hey... tle... u want a piece of fuscoe... ya gotta stand in line
*I don't want a piece of anybody. I'm way too slow of a typer to compete.Besides, I would probably embarrass myself.
*tle... no yust wat u mean.... i embarrass myself all the time... and the wife too...b what, me ? worry ?
*Roger:Basically, what Mike said in his first post.Additionally, APA (American Plywood Association/Engineered Wood Association) recommends panel spacing of 1/8" on the non T&G edges. For an introduction go the Tech issues & answers menu on the above web site and then the FAQ page. Read the FAQ entitled "How should wood structural panel edge spacing be considered by construction professionals?" Note that this brief description does not cover T&G, however if you order their literature, you will read that the T&G edges are most often "self spacing" and should be installed snug, but not driven up tight.
*Kermit,
View Image © 1999-2000"By the time a man realizes that maybe his father was right, he usually has a son who thinks he's wrong." Charles Wadsworth
*OSB has a strong tendency to swell at its exposed edges, not a lot of expansion along the sheet, so if you really want this crap for your subfloor, put em on like Gabe suggested and throw away the instructions. And get a roof over it fast.MD
*....i don't use OSB.. i'm talkin fir T&G, plugged and touch sanded...anf the famous joe fusco trench don't mean a single bit of difference...when the plywood is soaked... the plywood is soaked..cause...sooner.. er later...you will get caught in a rain storm ... or two... or three..then your sheets are gonna buckle and give you a god -awful mess ..unless of course you followed the mfr's instructions and didn't over drive the T&G.. and you left a 1/8 inch gap on the 4 foot ends breaking over the joists...course if u spent ur career laying decks in NYC, things might be differnt..joe, buddy, pal,, amigo, gumba..yur so wrong on dis one...hah, hah, hah..wat's it feel like to be wrong fer da foist time in yur life ?
*I've seen some houses where I think the original builder addressed the problem of puddling rain water by pitching the floors 1/8 in. per foot or so...
*One of the reasons for the difference of opinions here would be the time frame involved to cover the floor.The majority of 1,200 sq. ft. bungalows built by framing crews has the floor exposed for about a week before the shingles are applied.Two weeks if its a 2 level home.A DIY might have the floor open for a month or two before the shingles.Different strokes for different folks,Gabe
*Can you guys get OSB t&g with treated edges where you are or is that a regional N.W. thing?JonC
*Yeah, most of the T&G sturdifloor OSB I've used has a tough gray or green paint on all edges - and some has slots cut in the tongues for water drainage. No problems with swelling edges. We get a little rain here. little warm down in Oregon, Jon?
*Kermit,
View Image © 1999-2000"Whenever, therefore, people are deceived and form opinions wide of the truth, it is clear that the error has slid into their minds through the medium of certain resemblance to that truth." Socrates
*Andy,
View Image © 1999-2000"Whenever, therefore, people are deceived and form opinions wide of the truth, it is clear that the error has slid into their minds through the medium of certain resemblance to that truth." Socrates
*Warm but not as warm as yestarday fortunately.I used Weyerhaueser "edge gold" for the first time a couple years ago. It got wet several times with no problems in the joints. I remember at the time people were bitching about how much more it cost than the untreated. I just called my supplier to see how much more and was told they no longer handle the untreated. Didnt have slots cut in the tongues then. Just curious about if we're comparing apples to apples across the country when I hear about all these problems with swelling in the joints.JonC
*joe.....i've done the broom and drill bit too....that was fun... some years you make out .. some you don'tstill gapping the short end with my 8d nails..and still waitin fer joe to say how he was ...wrong wrongwrong(i'm not holdin my breath)Kermit's pal.. Mike
*None in Carolina that I've seen.
*jonc... Advantech is treated for the entire material...it is the one OSB / composite i would use .. as long as there is a savings over plywood.. which there isn't always..in some markets Advantech actually costs more than ply...
*Kermit,
View Image © 1999-2000"Whenever, therefore, people are deceived and form opinions wide of the truth, it is clear that the error has slid into their minds through the medium of certain resemblance to that truth." Socrates
*Joke, that was a joke. A 40 x 80 house pitched 1/8 per foot would would be, what, either 5in. or 10in. out of level, depending on the direction of pitch. Playing marbles or billiards would be out of the question. Andy
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View Image © 1999-2000"Whenever, therefore, people are deceived and form opinions wide of the truth, it is clear that the error has slid into their minds through the medium of certain resemblance to that truth." Socrates
*I'm weighin' in here.I've installed a zillion sheets of plywood, many of it T&G and for the last few years, most of it osb.I always, I REPEAT; ALWAYS space the panels 1/8" on the short edge and 1/8 inch on the long edge. The t&g is installed not snug, but not tight. I basically leave about 1/16" gap. I had to beg the guys to not pound it tight with the 16# persusader.It doesn't matter how fast they shingle it. If you lay it tight, you will be voiding the warranty. God bless you if they ever have to strip a few squares of shingles and replace your improperly installed sheathings. I remember having to do that as an apprentice and I have a long memory. Until alzheimers sets in, I will always install the panels with gaps on both sides.Incidently, I have had approxiamtely twenty instances of ply failure in my less than distinguished career. Each time the lumber man has come and checked to see if it was gapped properly. Each time they have honored the warranty and provided me with money for labor and supplied the new sheets free.Lay it tight if you are willing to accpet the risk. I know it takes a little more time to space it, but it also takes more time to dig the footings all the way below the frost line.You don't cheat there too do you?!!Oh yeah, we actually had one city inspector that started knocking down rough frames if the sheets weren't spaced properly. That was one area that I didn't have to worry about.blue
*Blue,The one thing I thought was missing in Joe's pictures was the voids. Last time I looked at the short end of a stack of t&g sturdifloor ply, I saw lots of voids. Have you had problems with any of the osb you've put down?JonC
*Sorry for the late reply JonC, we (my wife and I) have been tending to our daughter during a very difficult pregnency, and she's had my computer room tied up.Anyways, I've had ZERO problems with osb since I first started using it (extensively) about five years ago. I do think that there are many different grades of the stuff however and we do have very good grades around these parts.Even though it is heavier, I'd rather use it for all roof and flooring applications. I like it on walls too, but would rather be throwing down 1/2" cdx. But that ain't gonna happen. I'd rather sheet with osb than foam too. It just makes the walls much sturdier and therefore easier to keep straight and tight.And I haven't seen any swelling since the eighties when the stuff first surfaced. Osb has come a long way since then.blue
*To all except Joe, If you endorse spacing on the 4' joint, why not space on the 8' edge? Advantech claims that there is no need to space the 8' edge because the plies near the top are cut back an eighth or so to relieve the swelling. Still, if the reason to space is to eliminate swelling in the panel resulting from expanding dimensions ramming into each other, wouldn't a bubble still form in Advantech. I don't see how cutting back the topmost plies would take care of this. But, if they are successful in relieving expansion worries, couldn't one just kerf all the edges after installation? As far as the overall arguement goes, I've never gapped, been rained on alot, and never had expansion problems (using CDX Sturdi-Floor). Just my thoughts.Jon
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Ok this will probably be a dumb question in hindsight, but...
I know that one is supposed to leave 1/8" spaces between subfloor sheets for expansion. I also know that one should use T&G to avoid blocking on joints perpendicular to the joists. But one can't both use T&G and leave spacing. Doesn't seem to make sense to leave spacing only on the short side of the sheet.
I feel like one of those computers that Captain Kirk made go boom by posing puzzles like this.