Replies

1. 
   Crusty_ | Oct 02, 2000 06:20am | #1

   *
   I'm not a contractor, but wouldn't T&G give you problems with expansion? Seems like it's going to get awfully hot.

1. 
   The_Machine | Oct 04, 2000 06:19am | #2

   *Mr. Turner,Mr. Crusty might just be onto something. Any PEs out there know anything about that?The Machine

1. 
   Ryan_C | Oct 04, 2000 12:44pm | #3

   *I had a stack of T&G delivered in error once. So, I decided to just go ahead and put it on. Hard to use on a roof. Of coure, I think it's hard to do anything when you're up on a roof.

1. 
   Travis_Turner | Oct 08, 2000 03:04am | #4

   *Crusty: Thanks for the input; I'd thought about the pos. expansion problem, but don't seem to have it with the T&G Sturdifloor subfloor I use. The heat you mention would tend to make the plywood shrink, and proper attic ventilation should keep the roof plywood dry. I try to never jam T&G plywood completely together anyway. As irregular as plywood is now that's not a problem after a few runs. I always lay my first run to a chalk line, and have to reestablish a straight line after several runs because of variances in plywood dimensions and in the slight differences in the expansion crack I leave between each sheet. But still, the thought of T&G on a 9/12 pitch sounds aggravating. Would be nice and sturdy between the trusses tho...

1. 
   Michael_Eckert | Oct 08, 2000 04:30am | #5

   *Travis,If expansion was not a concern with roof sheathing there would be no manufacturers offering roof clips. As far as heat shrinking the plywood are you considering air humidity volume in relation to heat? The large heat/cool/dry/humidity changes that roofing goes through mean expansion/contraction rates that are wider than T&G used in a conditioned space.Why not call one of the Reps. for the T&G products? They should have the specs as to why or why not T&G would/would not work.

2. 
   Boss_Hog | Oct 08, 2000 01:18pm | #6

   *I helped a cousin frame an addition once, and he insisted on using 3/4" T&G on his roof. It was a big pain keeping a sledge up there to drive the sheets together with. It was a hip roof, and we had to be dang sure we oriented the sheets correctly when we cut them to fit the hip ridge. I really thought it was a waste of time, effort and money.

3. 
   arrowshooter_ | Oct 08, 2000 03:20pm | #7

   *I bought a stack of 3/4 plywood real cheap and used it to deck my roof. To make the job easier I stacked the plywood and ripped it lengthwise into 16 inch pieces, this was a lot safer and easier to handle,also it's thick enough so you don't need clips or the toung and groove, also you have less waisted material going into hips and valleys.

4. 
   blue_eyed_devil_ | Oct 08, 2000 04:33pm | #8

   *Michael, I sense that you are attributing a reason for clips that isn't valid. Clips are not used to create a space for expansion and contraction. They are not intended for expansion management in any way. Clips are a mechanism to "fasten" the edges of the sheet together. This "attachment" causes the sheets to ride up and down, in usnison, while being walked on. A snow load on one sheet will essentially bring both sheets down. This unified movement prohibits the tearing of the finished roofing products. It also prevents nailpops that would occur if one sheet was allowed to drop, then spring up again, while it's neighbor stood pat.blue

5. 
   blue_eyed_devil_ | Oct 08, 2000 04:42pm | #9

   *The use of t&g certainly falls into the "Boogerin' Blue" category of overkill. Yes, it would provide stable horizontal joints, but why do you care? Are you planning on having a dance party up there?If you want to continue the comparison, you certainly can get a much stiffer roof using 2x6 material. They make a nice 2x6 t&g and it is far stiffer than the "weak" t&g ply. You can also get thicker ply materials. So why stop at 3/4"?the alternative roofing materials were developed to save resources. In most cases, the minimum is probably a little light, but adequate, the next step up is fine, and any step higher is probably overkill. Remember, we are the stewards of our grandchildren's resources. My grandfather (a carpenter) used to "sheath" roofs with clear 1x12 pine. I've stripped roofs that contained virgin pine that you wouldkill to receive in a pile of select. Basically, they thought that resources were there to be used, instead of rationed. If we continue with that mentality, in the face of higher demand, we are only dooming ourselves to having less nice products in out children's future.Don't mortgage our grandchildren's resource future on un-needed extra strength. Build it strong, build it right, but don't be wasteful.blockless and still saving owls, blue

6. 
   Michael_Eckert | Oct 09, 2000 02:35am | #10

   *Blue,Clips do help prevent bowing but they are also designed for spacing the sheets. With both plywood and OSB the APA recommends that panels be gapped 1/8" at all end and edges joints. Their primary reason is expansion and contraction. This subject was covered (for OSB only) in FHB's More Frame Carpentry 1993.Lots of good information at the APA site:http://www.apawood.org/

7. 
   blue_eyed_devil_ | Oct 09, 2000 03:06am | #11

   *Michael, I've never seen a clip that was even close to 1/8". Most are half of that. Don't believe everythng you read, even if it's a FHB publication. I've seen more than my share of flawed information.I'll peruse the apa site. Thanks for the link.blue

8. 
   arrowshooter_ | Oct 09, 2000 12:48pm | #12

   *Blue:We must stop driving cars and trucks at once. No more air conditioning. Back to the way it was. All the ice is melting and we are doomed. Vote for Algore and the tree huggers.

9. 
   blue_eyed_devil_ | Oct 09, 2000 02:32pm | #13

   *Don't panic arrowshooter. I've got several boats. Let the ice melt. I prefer living near water and there will be more water when all that cold pesky ice disappears.Which boat do you want to borrow, the fiberglass duck boat with the small leak, or the canoe?blue

10. 
    James_King | Oct 14, 2000 05:56am | #14

    *Travis, I always use 5/8" plywood (5-ply) on a roof that is framed 24"o.c. I am a builder in Eastern Oregon where we experience a 25 PSF snow load on our roofs and have never had a problem. You don't need to use clips either. Good luck.

11. 
    jim_pelot | Oct 19, 2000 03:00am | #15

    *Hey Travis - We just built a new house in Northern Ontario, and the architect spec'd no roof sheathing to same materials. The trusses are strapped with 2x4's 2'oc, and a metal roof bolted to the strapping. Sorta off topic, but sure saves lugging a lot of material. DIY Jim

12. 
    Phill_Giles | Oct 19, 2000 06:04am | #16

    *How far north Jim ? PS, I saw a similar roof system at the Home Show: all the builders were asking about condensation problems in our climate and the potential to rust out the roof from below. Unfortunately, the booth was mostly staffed with people hired for the show (didn't you ever wonder why most show booths are staffed with at least one women who looked like she could have been a model in her youger days; well, she probably was) and the boffin was on his break while I listening for the answer.

13. 
    jim_pelot | Oct 19, 2000 04:27pm | #17

    *Phil - Burk's Falls, 40km north of Huntsville. The roof was covered with Tyvek before it was strapped, to leave a ventilation space below the roofing, above the insulation. The architect has used this design several times, and has never had a problem (although there was an interesting discussion between the builder and the architect at that point!)

14. 
    Travis_Turner | Oct 20, 2000 01:18am | #18

    *SHEATHING DISCUSSION... THANKS Thanks for all the input; I decided to skip the misery of T&G on a 9/12 roof and am using 3/4" cdx. I've use it in the past and it sure feels good. We used 1/2" cdx on 24" centers during the FHA days 20 years ago, but back then, you really got 1/2". I remember stripping a roof one time years ago that was decked with 3/8", but 16" centers as I recall. About like what we still call 1/2" noways. Thanks to all.

2. 
   Travis_Turner | Oct 20, 2000 01:18am | #19

   *
   I've been a builder for almost 25 years and have yet to use I&I plywood for roof decking, and haven't seen it on other jobs either. I know it'd be a pain, but with the decreasing thickness and quality of construction grade plywoods today, it seems it might be worthwhile on higher end jobs. And no -clips!! Anyone out her have any experience with I&I on roofs. I'm thinking of trying it on a 9/12 pitch truss roof, 2' o.. that I'm doing now. Appreciate any input. Thanks, from Tennessee. Travis