Plywood or OSB

[DTE]

I got the walls up on my building and will be getting it under roof next. So here is my question, there is quite a difference in the cost between plywood and OSB and I am putting metal on the roof with screws and the trusses 2 ft. on center and will use 19/32 plywood or OSB which is about half the cost. My concern is that does the OSB hold the screws as well as plywood .Any thoughts from those who have installed metal , which is better ? plywood or OSB

 

[Robinson1]

Honestly I can't tell any difference in it as far as holding the screws go.

OSB has pretty much replaced CDX grade plywood in all applications. Partly due to cost and partly due to the fact that it's good enough.

When giving a bid I always price it both ways but I can't remember the last client who told me to use CDX.

If I was building something for myself I would use OSB.

 

[hughfree]

I have been very happy with my OSB walls. I would recommend a high grade primer and paint when you finish the final product.

 

[gtae07]

I got the walls up on my building and will be getting it under roof next. So here is my question, there is quite a difference in the cost between plywood and OSB and I am putting metal on the roof with screws and the trusses 2 ft. on center and will use 19/32 plywood or OSB which is about half the cost. My concern is that does the OSB hold the screws as well as plywood .Any thoughts from those who have installed metal , which is better ? plywood or OSB

19/32 seems heavy for a roof; I used it on my walls since my studs are 24" OC, but I put 15/32 on my roof with rafters also 24" OC and it seems to work fine (and it exceeds the hurricane wind specifications).

At least around here, the 19/32 is about 50% more expensive per sheet. Why spend the extra?

 

[Cyberbear]

Being "old school" it seems to me that everything today comes down to price rather than long term durability. In times past the roof sheathing of choice was 1 x 6 fir which meant 3/4" thickness. Later, 3/4" ply replaced the fir, then as more time passed the plywood became thinner, to the point where I could see and feel the roof flexing when walking on it. Now we have OSB that is used more commonly by one and all.

I don't believe it takes a structural engineer to realize the obvious differences between ply and OSB, besides cost. OSB is yet another version and type of particle board but has larger wood bits and lots more glue. I do not consider wood chips and glue a long lasting quality building material, but it is accepted by most people, lay and professional. Personally, I prefer using the best materials for the job and if it fails for any reason, I know it was not because I chose to save money rather than build it properly. These are my thoughts about what is simply "good enough" and what is proper. Remember, the building code is the minimum standard, it's up to you to have better than minimum when you build something.

 

[reader2580]

Being "old school" it seems to me that everything today comes down to price rather than long term durability. In times past the roof sheathing of choice was 1 x 6 fir which meant 3/4" thickness. Later, 3/4" ply replaced the fir, then as more time passed the plywood became thinner, to the point where I could see and feel the roof flexing when walking on it. Now we have OSB that is used more commonly by one and all.

I've seen a building with 1x8s on the roof that the whole building moved after removing the shingles. They had to sheet the whole thing with OSB or plywood (Don't recall which) to stiffen it up.

The reason some of the materials were used in the old days was often they had nothing else. The building I mentioned earlier had 1x8s for the roof as they milled the lumber on-site many years ago. They couldn't make their own plywood, and they may not have used plywood if they could get it.

 

[homebuilt burner]

FYI I am building now and am using 2x4 stringers instead of plywood or OSB to screw my steel roof down. Also, you may want to consider a moisture barrier under the steel. I am not a professional builder but the ones I have talked to suggested this system.
Trusses 2' on center, 2x4 set 2' on center, moisture barrier/insulation to keep the wood structure dry as the steel "sweats", then steel.

 

[HanShotFirst]

I'm very happy with OSB...it's a bit of an eyesore when it's not covered, but it's good stuff. I like that it doesn't peel & de-lam nearly as easy as plywood.

 

[Toolfool]

I'm with Cyberbear. I've been in this business over 30 years and am not impressed with how quality and standards have declined over time. When building for a customer, some concessions have to be made for their budget and desires. But when I have control, and on my own projects, it's plywood all the way. Trusses on 24" gets 19/32" ply with H-clips , 30 lb paper, then metal roof.

Simple answer : I personally feel more confident in plywood's ability to hold a screw.

 

[mburrus]

i am always amazed when i read about builds that osb is used as much as it is. down here in south florida we have extremely stringent building codes, osb isnt allowed for anything, all roofs are 3/4 plywood... my house has much of the original 1x tongue and groove on the roof, and my shop will have 3/4 ply nailed and screwed. in hurricane alley there is no such thing as too strong... i would have used double tees or hollow core concrete if i could have afforded it.

 

[lane meyer]

OSB is commonly used because of cost. It'll delaminate much faster than CDX when it gets wet.

Back in my younger days I worked at a lumber yard, and all of the high end builders on the cape used CDX...I imagine there was a reason for that.

 

[PugetDude]

19/32 seems heavy for a roof; I used it on my walls since my studs are 24" OC, but I put 15/32 on my roof with rafters also 24" OC and it seems to work fine (and it exceeds the hurricane wind specifications).
At least around here, the 19/32 is about 50% more expensive per sheet. Why spend the extra?

When I built my garage on the Mogollon Rim in Northern Arizona, they wouldn't allow 15/32" OSB for roof sheathing. They required 19/32" due to nails pulling out in high wind conditions.

15/32" was allowed for walls only.

 

[Casey69]

i'd use osb; probably uses the same adhesives in it as plywood to keep it together.

i don't think i've ever seen a house constructed recently using plywood. even luxury homes use osb. not sure what the cost difference would be on an average sized home, but if it's a few thousand dollars more, most buyer would opt for a fireplace/granite/upgraded carpet/etc.

osb has been around for 20+ years & i'm not seeing it fail. when plywood came along, i bet people complained about it too.

 

[valentine]

I'd never opt for OSB over plywood. Plywood has greater tensile strength, impact resistance, resists de-lamination better and so on. I've seen many pickup beds lined with an un-finished sheet of plywood which held up to hard use for years. Never saw that tried with OSB. Finally; they build boats out of plywood. Try that with OSB and you'll be sitting next to the Titanic.

-Valentine

 

[redmondjp]

There are huge differences between OSB and plywood as far as strength goes. Plywood is made from several layers of continuous wood "peels" which have a unified grain structure. The grain direction is alternated between layers. This makes plywood incredibly strong and you have continuous wood fibers that are either 4 or 8 feet long in any given layer.

The wood fibers in OSB are relatively short - typically less than a foot long, and discontinuous and randomly-oriented (hence the name, Oriented Strand Board). Even on a good day and when kept dry, OSB absorbs moisture and swells, to the point that its thickness gain measurable (1/16" gain on a 7/16" initial thickness). Plywood, kept under the exact same conditions, absorbs far less moisture and won't swell to a measurable amount.

In the application discussed by the OP, I would probably use the OSB, but as mentioned in another post, put 30# tarpaper over it as an additional moisture barrier (condensation forms underneath the metal roofing, like it or not).

 

[Casey69]

I'd never opt for OSB over plywood. Plywood has greater tensile strength, impact resistance, resists de-lamination better and so on. I've seen many pickup beds lined with an un-finished sheet of plywood which held up to hard use for years. Never saw that tried with OSB. Finally; they build boats out of plywood. Try that with OSB and you'll be sitting next to the Titanic.

sure - if i were building a house & the price were the same, i'd opt for plywood too; it's a better product. no way i'd pay more money for it though. you certainly wouldn't make your money back when selling it. very few buyers would give two craps about plywood construction in a real estate listing.

most buyers live in a house for what, 10 years? time will tell w/ osb, but (imho) it's proven itself as a good alternative to plywood.

 

[Casey69]

The wood fibers in OSB are relatively short - typically less than a foot long, and discontinuous and randomly-oriented (hence the name, Oriented Strand Board).

minor disagreement, but (like plywood) the wood chips/fibers in OSB are actually oriented into opposing layers to make it stronger.

 

[DTE]

Well for me I am un-decided, all of you make some valid points. Price is what gets my attention the most and it seems to me that plywood should hold a screw better. But I had 17 sheets of plywood de-laminate a few years ago when we were remodeling our living room and I have never looked at plywood the same.

 

[theoldwizard1]

OSB is fine for roof decking. Properly installed metal roofing, should not allow water to penetrate to where the screws connected to the wood.

Standard (asphalt) roof decking is 7/16" (13/32"). I paid extra for 1/2" (15/32"). You should be good with 9/16.

Delamination of plywood is from water getting in through the edges. OSB swells and looses its rigidity when it is water logged. It is interesting that they are selling "premium" decking/sheathing material. Man made outer skin, more water resistant glue and no voids on any of the inner plys.

 

[redmondjp]

OSB is fine for roof decking. Properly installed metal roofing, should not allow water to penetrate to where the screws connected to the wood.

Standard (asphalt) roof decking is 7/16" (13/32"). I paid extra for 1/2" (15/32"). You should be good with 9/16.

Delamination of plywood is from water getting in through the edges. OSB swells and looses its rigidity when it is water logged. It is interesting that they are selling "premium" decking/sheathing material. Man made outer skin, more water resistant glue and no voids on any of the inner plys.

The water that you have to worry about will come from condensation that forms on the underside of the metal roofing. Even if that condensation only forms in the raised channels, it will still form and drip down onto whatever is below it. Hence the 30# tarpaper or other moisture barrier above the OSB.

 

[f150skidoo]

Up here it seems like most houses with OSB roof you will be able to see the trusses after about a decade from the house being built. I guess the weight of the snow on 24" centers will make the OSB sag.

 

[redmondjp]

Up here it seems like most houses with OSB roof you will be able to see the trusses after about a decade from the house being built. I guess the weight of the snow on 24" centers will make the OSB sag.

I have 24" centers also on my house, and there was a repair made to one section of roof sheathing that was OSB - it was spongy and sagging, even though there was no apparent leak onto it. It got replaced with plywood when I had the roof replaced.

YMMV

 

[mtwaterguy]

I got the walls up on my building and will be getting it under roof next. So here is my question, there is quite a difference in the cost between plywood and OSB and I am putting metal on the roof with screws and the trusses 2 ft. on center and will use 19/32 plywood or OSB which is about half the cost. My concern is that does the OSB hold the screws as well as plywood .Any thoughts from those who have installed metal , which is better ? plywood or OSB

You should be screwing the metal roof to the purlins not the plywood or OSB. I use OSB under my metal roofs. The only reason is to prevent noise from the metal roof. In Orygun where it rains almost everyday the noise can make having a conversation nearly impossible.

 

[CNGsaves]

For roofing . . . OSB ***** . . . plain and simple. Doesn't do much at all to strengthen roof as it's so easy for tearouts of whatever you use to attach it (ie staples, nails, etc.) Lazy or cheap installer often just staple and I can tell you that's **** as OSB will be moving and sagging in no time. I want FIRM roof that is NAILED plywood.

OP since you are putting on METAL . . . you can probably get away with OSB but realize that for one-time savings, you will FOREVER have a flimsy roof structure. If the roof develops a leak and it gets past tar paper, your OSB will be turning to mush in no time.

IF that building might ever have shingles instead of metal . . . then I'd 100% go with plywood. By EVERY measure plywood is superior product to OSB. Like the Florida comment from GJer, go with BEST product if you have hurricane or wind standards that want a better product, which plywood certainly qualifies.

Menards had special recently for 1/2" 3 ply CDX plywood for $15.47 a sheet which is a TERRIFIC price. OSB runs around $9 or $10 a sheet in comparison. For that difference I'd go plywood without even blinking an eye. Recently helped fix a friend's roof and best price there on plywood was $18 to $20 a sheet and still went with plywood over **** OSB at $9 sheet.

Tell us your cost difference (per sheet) & how many sheets you're talking about.

 

[The Cobbler]

Now people would rather have more show than a better structure. so if you save 30% by using OSB instead of plywood, you can use that money to buy big MDF trim and make it look nice... that's the world we live in now.
In washrooms, I have replaced more OSB subfloor than plywood, and more plywood than 1X6 spruce or fir planks because of rot. OSB does not like water at all. plywood somewhat more tolerant & actual planks are more tolerant than anything.
For my garage build, it's going to be 1/2 ply ext. walls, 5/8 ply roof and undecided on interior, might be some osb in there on the walls.ceiling probably going to be 5" v match pine planking. mind you the ply & pine was a great deal, but I would still have gone with ply on the roof if I was buying it all.

 

[DTE]

Where I am we have Lowes, Home depot and a couple private stores. The plywood at both of the box stores looks like junk to me. The one private store is where I got the plywood that de- laminated so I am still looking. 15/32 is not a option for me. 19/32 osb is 12.47 and 19/32 plywood at he box stores is 19.97. I need 32 sheets. It is not like it is going to undo my project but old habits die hard and it is very rare that I ever have to do something a second time. but when you look at the 2 products side by side the osb looks more solid.

 

[reader2580]

My previous house I believe had OSB for the roof sheeting and there was no bowing after 12 years in snow country. The builder did use plywood for the walls.

 

[Toolfool]

Well for me I am un-decided, all of you make some valid points. Price is what gets my attention the most and it seems to me that plywood should hold a screw better. But I had 17 sheets of plywood de-laminate a few years ago when we were remodeling our living room and I have never looked at plywood the same.

Was that possibly imported goods you purchased at a "good price"? There was a lot of that going around. And plywood that's not exterior grade (CD"X") will delam with moisture exposure. Check that your plywood comes from a North American mill.

 

[zable9]

Being "old school" it seems to me that everything today comes down to price rather than long term durability. In times past the roof sheathing of choice was 1 x 6 fir which meant 3/4" thickness. Later, 3/4" ply replaced the fir, then as more time passed the plywood became thinner, to the point where I could see and feel the roof flexing when walking on it. Now we have OSB that is used more commonly by one and all.

I don't believe it takes a structural engineer to realize the obvious differences between ply and OSB, besides cost. OSB is yet another version and type of particle board but has larger wood bits and lots more glue. I do not consider wood chips and glue a long lasting quality building material, but it is accepted by most people, lay and professional. Personally, I prefer using the best materials for the job and if it fails for any reason, I know it was not because I chose to save money rather than build it properly. These are my thoughts about what is simply "good enough" and what is proper. Remember, the building code is the minimum standard, it's up to you to have better than minimum when you build something.

Hear hear

 

[CNGsaves]

My previous house I believe had OSB for the roof sheeting and there was no bowing after 12 years in snow country. The builder did use plywood for the walls.

You likely had good install and steep roof which helps a lot . . . plus I bet all the OSB was properly nailed and clips where necessary.

COMPARISON: That friend's house I worked on roof, the cheap **** prior roofers only used around 20 STAPLES for each 4' x 8' sheet of OSB they used for patches of the original plywood that had gone bad (house built in 70's and re-roofed in early 90's). Virtually every sheet would bow and creak when walking across giving no confidence at all. I ended up pulling any of the 3/8" crown x 1 1/2" staples that weren't fully nailed (ie as they weren't holding much and protrusion upwards interfered with underlayment). I re-nailed (3" ring shank nails) for all of their OSB sheets that remained in place with around 50 nails per sheet which did stiffen them up a bit. However, the OSB even when nailed was no-where near as firm as nailed plywood. I'm a believer of plywood for roof sheeting.

Local lumberyard in that small town had "street price" of $22/sheet for 1/2 CDX plywood, which he marked down to $20/sheet since I bought whole roof of shingles. The Lowe's another 10 miles down the road was $18.50/sheet for 1/2 CDX plywood. I never put a single sheet of OSB on roof, especially since it has very little slope and prior roof had rotted so bad in spots that I nearly stepped through roof !!

 

[TCAS]

This is where the future is headed in wall and roof sheathing...

ZipSystem ==> http://www.huberwood.com/zipsystem/products/zip-system-roof

 

[Toolfool]

This is where the future is headed in wall and roof sheathing...

ZipSystem ==> http://www.huberwood.com/zipsystem/products/zip-system-roof

Not necessarily. They said the same about SIPs years ago and they still are far from the standard. Some of these companies try to "revolutionize" the industry, but they just become a niche product at best.

 

[Elginz]

I have used the 5/8 (19/32 by today's dimensions) OSB under the metal just for the screw holding when 1/2 would have been enough otherwise. Using Menards Premium Pro-Snap metal. I like not having the screw heads exposed. I do use synthetic underlayment and and plastic cap nails to have a good layer of protection, and yet I use OSB. Any thing that keeps getting wet will fail, and CDX still has voids in it, and I do think OSB holds a screw better in general. I like solid, smooth OSB.

 

[DonPowers]

I used 5/8" AdvanTech over trusses that are 2' on centers.

http://www.huberwood.com/advantech/home-advantech

Also did a few screw driving trials on a scrap piece of AdvanTech using different torque settings on the driver. If not careful, tear out can occur.

As previously mentioned by others, condensation can occur under the metal panels. Not wanting to mess around with future problems, I covered the entire roof with High Temperature Water & Ice Shield, followed by a layer of Grace Tri Flex.

View media item 47917
Also installed a roof hatch to facilitate access during construction and any future needs.
View media item 45824

 

[valentine]

sure - if i were building a house & the price were the same, i'd opt for plywood too; it's a better product. no way i'd pay more money for it though. you certainly wouldn't make your money back when selling it. very few buyers would give two craps about plywood construction in a real estate listing.

most buyers live in a house for what, 10 years? time will tell w/ osb, but (imho) it's proven itself as a good alternative to plywood.

I agree with you that MOST buyers don't really care about details like plywood versus OSB, but I don't understand why you wouldn't pay more for plywood when you agree that it's a better product. Better products typically cost more money because they perform better, last longer, have higher resale, etc.Not always, but usually. Also, i have no idea how long the average buyer lives in a house but if it is 10 years, What happens after that? I always felt that homes should be built well enough so that your descendants will be living in them and enjoying them. I wouldn't even build a shed from OSB. I think the cost of plywood over OSB is minimal but the service life advantage it gives is significant.

-Valentine

 

[Jackfre]

I used the radiant barrier osb on the roof of the shop. It was 102* yesterday and I went up in the attic to check it out. With the ridge vent, gable end windows open and the barrier sheeting, it was hot, yes, but tolerable. Otherwise I detest OSB.
I ordered the 1/2" plywood for the ext walls. I then had to travel on business for a week and when I returned the crew had all the sheathing up. It was OSB. The meatheads at the yard had the order for plywood but delivered osb, so it is up. One highly PO'd customer. Corrugated 7/8" Corten siding and the interior walls are plywood.

 

[valentine]

Sorry to har about that Jackfre, I'd be highly pissed off if I were in your shoes. In fact, I don't know if I could ever feel the same way about a project if it wasn't done to my specifications. I'm kind of quirky that way and it would be ruined for me. Hope that you are able to find some favorable resolution and get something you are happy with.

-Valentine

 

[reader2580]

I agree with you that MOST buyers don't really care about details like plywood versus OSB, but I don't understand why you wouldn't pay more for plywood when you agree that it's a better product. Better products typically cost more money because they perform better, last longer, have higher resale, etc.Not always, but usually. Also, i have no idea how

Seriously, how many buyers ever ask what type of roof sheeting or wall sheathing a house has? How many sellers could even answer that question? I bought a house last fall and I really have no idea what type of roof sheeting it has although I suspect plywood due to being built in 1980.

I have Bildrite sheathing on most of my house and on my garage and that stuff *****! It has minimal water resistance and minimal resistance to impact damage. I am re-siding my garage and had to replace eight or nine sheets of the Bildrite due to water damage or large holes.

Part of my house added on in 1986 has foam sheets for the wall sheathing.

 

[DTE]

Well I spent the extra money and went with the 19/32 plywood. I think in the long run it will pay off.

 

[redmondjp]

Well I spent the extra money and went with the 19/32 plywood. I think in the long run it will pay off.

Excellent choice, but I would have gone with the 38/64" myself!