Roof Decking?

[karoc]

Good morning guys, question about roof decking thickness. It’s always been in past practice if trusses are 24” OC then it’s 5/8 plywood. But now days it seems that’s no longer rule of thumb. Case in point, friends neighbor is having pole barn built 35’x80’ with trusses 24”OC and metal roof. And decking is 7/16 OSB, which the contractor is saying that is new normal. I am having hard time wrapping my mind around this, it just doesn’t make sense. But maybe this is new normal cause where I’m at it’s hard to find 5/8 or 19/32 plywood or OSB which I am wanting foil radiant barrier. There’s no snow load, no inspections of any kind. I’m just old school but I sure would like save few bucks.
So I sure would like y’all opinion on roof decking thickness. Thanks guys for y’all thoughts

 

[jkeyser14]

7/16 is normal now in Maryland, even with snow load. Our house was built that way in 2017.

 

[FredWanaker]

this house was originally 7/16. It is 43 years old. When I re-roofed three years ago the city made us lay down 1/2" over it, or we could have torn off and replaced with 1/2". Walking on the 7/16" I could always feel it spring. 1/2" is code here now in NorCal.

 

[mike93lx]

I wouldn't do less than 1/2

 

[Moss]

I wouldn't do less than 1/2

This is what came to my mind as well. The last roof I did for my own project I went with 1/2 plywood

 

[Jeff C]

7/16” is standard for 24” OC with plyclips at the joints. Yes, you could spend more for 1/2” or 19/32” but if the budget is tight (and whose isn’t these days) I’d keep the savings for something else.

 

[Pluribus]

I'm doing 7/16" on a shed I'm building, but I wouldn't put less than 1/2" on a house or shop.

Unless I find some reason to not do it, I'm going to run the sheets vertically to have all the edges supported. It's an 8' wide shed, and my sheets are 10' (for overhangs,) so I'm not worried about running sheets in the weaker direction.

 

[BillK]

and metal roof.

I think this is the key. Metal roof really does not need the support like asphalt shingles do. That being said my house in Maryland was built in 1978 and has 1/2" plywood on 24" oc trusses. We replaced the roof about 15 years ago even though it really didnt need it. So its been surviving fine like that for 45 years.

 

[oldmxracer]

Yes it is the NEW normal and it will function but even with the clips it will be a soft deck. You can feel them when walking across.

 

[MushCreek]

I've seen roofs where you can see the trusses under the roof deck where the sheathing has sagged a bit. I went 5/8 on my house.

 

[karoc]

Thanks guys for suggestions which is eye opener. In my area it’s not easy find anything other than 7/16. I really want radiant barrier in 19/32 but seems not one has it or want to order it. But going keep looking till can’t wait any longer then go with 7/16 radiant barrier

 

[rd65]

My FIL who was in construction told me to never let them use OSB as decking for roofing. My shop is pole building with asphalt roofing, thank you HOA . The company always spec'd plywood over OSB. When the house was reroofed 2 years ago I thought I was getting plywood in areas that needed to be replaced but they used OSB, just like the original decking. I am sure location has a lot to do with it. I am north of Seattle, lots of wet days, so OSB is probably not the best thing to use vs plywood. So far we have had 71 wet days, just over 11" of rain for 2023. First day in the 70's is supposed to be this Friday.

 

[NUTTSGT]

I wouldn't do less than 1/2

Plywood or OSB ? Got a preference Mike ?

Normal around here is 1/2" OSB w/clips 24" OC.

 

[mike93lx]

Plywood or OSB ? Got a preference Mike ?

Normal around here is 1/2" OSB w/clips 24" OC.

I'm far from an expert on any of this, but my go to would either be a high quality osb, like Zip, or plywood.

OSB is nice in that it is dimensionally accurate and lays flat, but the cheap stuff is pretty poor quality.

I used LP techshield for a recent shed roof and it seemed fine. 7/16, but on a 16oc roof. The walls were GP forcefield (coated like Zip, but not as high quality).

The span rating on commodity 7/16 osb is 16", but 15/32 ply is 32". Yes, it's double the cost, but a lot stronger. Mid way in that price range gets you GP forcefield and a 24" rating.

 

[Hank11]

Its a small building (24X30), but my shop roof is 16" centers, with 1/2" zip sheathing. It cost $230.00 more than the 7/16".
Easy decision.

 

[red61cj5]

When I built homes in the 90's (also in MD) they were mostly 7/16 osb with clips over 24" spaced trusses.

 

[ddurrett896]

I will use OSB/Zip for sheathing, but always 5/8 or 19/32 ply on the roof.

 

[racecougar]

Case in point, friends neighbor is having pole barn built 35’x80’ with trusses 24”OC and metal roof. And decking is 7/16 OSB, which the contractor is saying that is new normal.

Why bother with decking if it's a pole barn with a metal roof?

 

[cliffcharb]

4 ply 19/32 sheathing required for my garage build in florida

 

[karoc]

Why bother with decking if it's a pole barn with a metal roof?

Mine is stick framing, Pole Barns guess it’s optional to go with decking or not. My question is thickness, seems lot contractors go with 7/16 decking.

4 ply 19/32 sheathing required for my garage build in florida

Hurricane country, I’ll have research 4ply but seems choices are limited here. I’m building to somewhat hurricanes in mind

 

[Renegade1LI]

How big is your roof? Remember code is the minimum requirement, I know you said no inspection but I would always build to exceed code, just good practice. I would install 1/2" at a minimum and screw the edges, it's your house so it's worth the extra cost and effort.

 

[billconner]

Well, odd man out. Used 1" rough sawn on rafters 16" o.c. Was less expensive (.50/bd ft) and you could have a barn dance on it. Looks better from inside also, imho.

 

[dcg9381]

And decking is 7/16 OSB, which the contractor is saying that is new normal. I am having hard time wrapping my mind around this, it just doesn’t make sense.

That's what my house is done in. We didn't do radiant barrier due to using foam.
I find 7/16 OSB to be pretty crappy in terms of roof decking, especially as I'm over 200 lbs.
Course, you can tell a contractor to use whatever materials you, just gotta pay for 'em. I like zip-R, but cheap it ain't.
Traditional insulation, I'd want a radiant barrier roof deck.

 

[Renegade1LI]

Well, odd man out. Used 1" rough sawn on rafters 16" o.c. Was less expensive (.50/bd ft) and you could have a barn dance on it. Looks better from inside also, imho.

That's not a bad way to go, my house on LI is sheathed with 3/4" T & G cedar, has held up great.