Couple quick roofing questions.
1) What size sheathing should I use on a roof 12X20 outbuilding? Thinking 1/2″ 4X8 CDX.
2) What size nails do I use and spacing
3) Do I use a staple gun or nails to hold the roof felt down? Size
4) What size (should I know) nail for standard roof shingles?
Thanks,
Ted
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Replies
Personally I wouldn't use anything less than 5/8 ply on the roof no matter what the spacing.
I use 8 penny cc nails 4" center on edges 6" center in the field. I know a few guys who go 6 on the edges and 8 in the field.
staples on the felt 1/4 or 3/8 i use a slap stapler mostly but do have the "fully automatic" air stapler. I would also suggest #30 felt and not wasting time with #15 felt.
If it is a new roof which this seems to be I use 1 1/4 roofing nails in my shingles hope this helps
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Ted,
5/8" OSB for the sheathing. I quit using plywood some years back because of the plys delaminating (even when covering with felt before dew or rain could settle on it).
I use 2 1/2" (8s) @ 6" o.c.
Cover with #30 felt nailing with button caps. Steer clear of #15 felt unless you plan to cover with roofing material immediately and the pitch is low, (#15 will tear under you feet if you have a steep pitch.
kcoyner
Uh boy. Here we go.
Maybe it's a regional thing, but, I wouldn't think of using OSB on a roof. I'd consider Advantech because I hear such good things about it and love using it for a subfloor. But the standard around here is 5/8" CDX. 1/2" for the cheeseballs. Regular OSB wouldn't cut it.
diesel,
I haven't seen plywood used for anything here for about 8-10 yrs. My supplier keeps about 100 sheets of each size on hand to sell when someone asks for it. I changed walls first to save a few bucks. Then I started having to replace 3/4 T&G plywood because the stuff was delaminating so I switched to OSB.
The last straw for roofs came when I had to remove sheathing from a roof and replace it at my expense for the labor. Around here it's total "Monkey Board" for everone. I do have a job coming up that will be total plywood and I have to special order it. I adjusted my contract to cover my backside in case of problems.
kcoyner
No kidding, huh? Wasn't trying to rip your practices, just noting the regional differences and opinions. Are you on the coast somewhere? Just curious.
diesel,
It's probably a regional thing (here in VA). I know you weren't ripping me and I never would have changed had I not had some TERRIBLE experiences. I'm slow to change my practices and to a greater extent, materials. I'm one who take's the "let's wait an see" attitude towards new materials. But a few more jobs like the one I had to replace the roof sheathing on and I would have been belly up! The manufacturer compensated me for the material but I had to eat the labor. It's really rough tearing it up and sheathing the roof a second time. I got to looking around and doing some research and realized I was one of the only builder/framers around not using OSB, so I made the change with some hesitance but have been pleased with the results thus far.
kcoyner
Strange what u say about plywood and the de lam problems, been using it for over 20 years and except for an occassional piece i havent had any problems except for the huge price increases
As for roof sheathing 1/2" 5 ply iis the way to go if 5/8 is to heavy for you. Remember to turn down the gun pressure and make sure who ever nails off hits all the rafters without any shiners
Remember fir is better than pine ply but there is a big diff in price
Wood,
Yea I thought it was pretty strange. We even tried sealers for the floors wasting more time and money. Once after delam problems, we had a rep to our job site who said that no sealer was going to help the problem. He said the problem was there when the hacks left the mill. I pumped him a little but he wouldn't elaborate.
I use Advantech on floors now. The floors got wet but when I started having problems with the 5/8 ply sheathing on the roof I was baffeled. When we sheathed a roof we quit early enough in the day to cover whatever we put on that day with felt, a practice that has carried over to 7/16 and 5/8 OSB roof sheathing.
I live in VA and like I said it's Monkey Board city. I haven't had problems (never had to replace a sheet) with the stuff but it still rubs against my grain a little. I guess plywood rubbed the old timers who used 1x storm sheathing the wrong way also and some were slow to change but finally did so when the crew down the street was framing a house in a fraction of the man hrs using plywood.
kcoyner
I have never used osb on a roof but the last time i used it as wall sheathing i noticed that even when Tyvecked any horizontal exposed seams, like before the rafters go on , would swell considerably. Also it doesnt cut as clean as plywood or seem as rugged in between studs. We actually joke that osb stands for old sh*tty boards that the mills finally found a use for. Also i heard that they coat the osb for roofs that makes it real slick.
I guess its like you say about being set in my ways I still wont do vinyl unless its already on the house to me this is siding for roofers not carpenters. But i love the composite trim go figure
We had trouble with the seams on OSB swelling so much they telegraphed through the shingles on roofs. There seemed to be a lot of soft spots where the nails from the nailgun would go right through. I didn't like OSB, but it was popular and a lot less expensive than plywood.
Regarding OSB vs. Ply and nailing practices, does anyone use a framing stapler for fastening sheets to either walls or roofs? In my area it is a widely used tool.
Also, a person would be hard pressed to see a house with any kind of ply on either the roof or walls in the sub divisions around here. Everyone, including me, generally skicks with 1/2 OSB on a roof, using H clips, and 7/16 for walls @ 16 OC.
Maybe this isn't accepted nationwide, but it works here. Someone mentioned availability of material. This is true here, as most suppliers have everything you'd need in OSB stock, but ply would be harder to come by in large quantities.
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Advantech is becoming the standard around here. It's real nice for installing copper on.
I am carpenter but do occasional roofing. I work from the Canadian building code but it would provide reasonable guidelines for most areas of the continent.
1/2" sheathing is fine provided edge support like H clips is used between rafters/trusses. Significantly lighter for handling than 5/8" and less expensive to boot. Spiral 2-1/2" nails hold well. Code minimum is 6" on edges, 8" in field.
Most roofers use coil nailers for shingling so they typically use that for holding down felt as well (less tools on the roof equals less hassles). One more reason for skipping 15lb felt and using 30 for everything: coil nails will go right through 15 lb unless the air pressure is turned down (price per roll is the same but coverage is half). Use 1-1/4" galvanised roofing nails for the shingles and follow the manufacturer's installation guide. Interestingly the Canadian code doesn't require any felt at all on the roof at large, just waterproof eave protection for 2' in from the wall plate line. Having said that, I can't recall seeing a roof being shingled without felt all over.
1. Sheathing thickness is determined by the rafter spacing, not the building size. The rating is stamped on the material, for example, a sheet of plywood might say
APA Rated Sheathing
32/16 1/2 INCH
This means the sheathing is rated for up to a 32 inch support spacing on roofs, and 16 inches on floors. Depending on the grade and rafter spacing, you could go with as thin as 3/8" plywood, though it gets a little bouncy to walk on, so 1/2" isn't too thick. In a high-end or high-budget job many framers would go thicker, but if you'd rather keep the costs in line, you would not be doing a substandard job by using the thinnest plywood rated for your rafter spacing, especially with no snow load.
Plywood will hold up better and hold nails better than OSB, especially if it gets rained on before the shingles are on.
3. You can use either to hold the roofing felt down so long as the shingles are applied before it's windy. In a practical sense, if you are applying the felt and shingles the same day, and it's not windy, staples are adequate. But, if you will be leaving the felt exposed for a couple of days, roofing nails with the little tin "buttons" are necessary.
4. The nails only have to go through the shingles and all the way into the sheathing. Any additional poking through doesn't help, obviously. So, with standard weight shingles 1" might be enough, but nails are so cheap that 1¼" would not be throwing money away.
> The nails only have to go through the shingles and all the way into the sheathing. Any additional poking through doesn't help, obviously.
The other thing to consider is how you're going to use the inside of the attic. Nails sticking down everywhere are an annoyance if you're going to be up there often because you use it for storage.
-- J.S.
I just re-roofed my place. I built it 23 yrs. ago when the kids were small and the budget was too. I used 1/2" fir CDX on the front and 1/2" SYP CDX on the back. 24" OC trusses, metal clips, 6d gal. 6" spacing + -, 15# felt, 3 tabs with 8" gal.drip edge around perimeter. When the roof was stripped the plywood was as new, front and back. Sheets were solid and flat. Today we would be called slipshod if we did not use 5/8" but the truth is that the extra money would be better spent on longer life roofing especially on outbuildings or garages.
I used 1" nails on the eaves and rakes so they would just barely poke through the sheathing and not look as ugly as a 1-1/4 would.
You didn't mention pitch. Is it steep enough for shingles?