# Using OSB on exposed areas?



## fosgate3 (Aug 2, 2020)

Hi Building Code Forum. I have a roofing question for you. My mother-in-law's house was recently roofed by a local company. I will try to keep this concise so here goes:

Her house is an early 1950s Craftsman Bungalow style, with exposed overhanging eaves and rafter tails (no soffit). The front porch roof was rebuilt sometime before she had the house and has 1/2" plywood on it while the rest of the house uses 1x6 tongue-and-groove material, typical of the period. A section of the porch roof eave was damaged by a tree and rotten; and had to be replaced. 

The house was roofed last week and after inspecting the job, we have a number of concerns. It was all covered by insurance so we haven't signed off on anything yet. One of the main concerns we have is the use of OSB instead of plywood on a large area of the eave of the porch roof. Instead of going back with 1/2" plywood like what was on the rest of the porch roof, the roofing company went back with 1/2 OSB. When I brought it to their attention, the guy told me that the shingle manufacturer, Atlas, recommends OSB on the roofs. I cannot find that information anywhere and I'm waiting for verification from Atlas (I checked on the shingle package and online). What's more is that this is an exposed area and it doesn't make sense to me why this would be considered "okay to do" by the roofers. I thought it was part of IRC/IBC but I'm not finding anything yet so I am coming here to ask the professionals of this forum if using OSB in an exposed area on a roof such as the eave is against building code. 

I'd include a picture but haven't yet figured out how to upload one. Maybe that will come with time. Thanks in advance for taking the time to read this.


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## fosgate3 (Aug 2, 2020)

Here's a link to a picture of the eave of the roof....I hope this works right. If it does, you will see many of our concerns in this one picture. 

1) The issue with the OSB in an exposed area
2) The flashing for the parapet wall is completely wrong and looks hideous. 
3) The barge rafter looks like sin (not sure why they did it out of two 2x6s instead of one straight 14' 2x6).
4) That 2x4 "support" block for the barge rafter shouldn't be there.
5) The 10,000 nails sticking through the roof material totally ruins the concept behind the architectural style of the home (and yes, it's like that all the way around the house).


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## fosgate3 (Aug 2, 2020)

It doesn't look like it worked so here's a direct link to the image:
https://ibb.co/MRgSFQH


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## cda (Aug 2, 2020)

I asked for my house, and told OSB was fine for decking, because plywood tends to delaminate.

As far as exposed, I cannot answer that question.

As far as exposed nails, kind of nature of the beast.

Give it a few days for better answers


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## north star (Aug 2, 2020)

*= > < =*

Here is the image posted by ***fosgate3***









*Q1):*  What is the applicable Building Code & edition in your area ?
*Q2):*  Did you or the Roofing Contractor obtain a re-roofing permit ?
*Q3):*  Did you sign a contract for the re-roofing ?.................If so,
what does that contract language state that they will do ?

***fosgate***, ...I looked in the `18 IRC for requirements of the
roof decking materials and did not see anything specifying the use
of "regular" plywood vs using OSB.......If the spacing of the roof
rafters is 24" o.c., then Table R803.1 requires a roof decking material
to be 5/8" thick.................The application of the "sidewall flashing"
in your photo appears to be incomplete and incorrect............There
should not be any gap behind the flashing and the framing to
which it is attached.

*= < > = *


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## ICE (Aug 2, 2020)

The flashing is the only code violation that I see.  As to the use of OSB on an overhang...OSB can be used on an overhang if it is rated for the exposure.  The shingle manufacturer did not recommend OSB as opposed to plywood.  Plywood is a superior product for an overhang both from a maintenance standpoint and aesthetically.

The nails protruding through the sheathing is not a code violation.  Short ill-fitting fascia is not a code violation.  Both are lousy workmanship and as a consumer I would reject that.  Since the job is an insurance repair, the contractor would have to get your permission to use OSB.   All of the overhang would be replaced with V-rustic and if I found even one shiner they would do it over again.

Check the contract and see if it says plywood.  Whereas the code allows the substitution of OSB for plywood, if a contract or plans specify plywood substitution is not allowed.

Ask your insurance agent to make a site visit and stand your ground.

Place a link to pictures of the fascia, roofing planes and vents (attic and plumbing)


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## fosgate3 (Aug 2, 2020)

ICE said:


> The flashing is the only code violation that I see.  As to the use of OSB on an overhang...OSB can be used on an overhang if it is rated for the exposure.  The shingle manufacturer did not recommend OSB as opposed to plywood.  Plywood is a superior product for an overhang both from a maintenance standpoint and aesthetically.
> 
> The nails protruding through the sheathing is not a code violation.  Short ill-fitting fascia is not a code violation.  Both are lousy workmanship and as a consumer I would reject that.  Since the job is an insurance repair, the contractor would have to get your permission to use OSB.  All of the overhang would be replaced with V-rustic and if I found even one shiner they would do it over again.
> 
> Ask your insurance agent to make a site visit and stand your ground.



ICE, this is exactly the information I was looking for. I have long since been told that plywood is superior to OSB for the reasons you just gave. When they delivered the materials, I noticed a sheet of OSB there in spite of the house having no OSB at all. I spoke with one of the people in charge and he first said "well, we have to go back with what's on the roof". When I told him that what's on the roof is 1/2" ply over the porch and 1x6 T&G on the rest, and that there's no OSB anywhere in the house, then he said he would make sure they did ply. I was out of town and came back when the job was done but not before anything was signed off. When I spoke to the same guy again, he made the claim that OSB was recommended, like I described in the original post. I don't like the OSB at all because it will stand out even when painted. It's in two places on the house over the eaves and looks like crap. 

Regarding the fascia, we originally told them we didn't want it on there at all. It was not how the house was originally made and was added years later but only in places. We wanted it all taken down and they said they would but then didn't---but then only put new fascia boards up in some places while leaving other places with nothing or old damaged fascia. So either way, it was a bad job done. 

You stated the contractor would have to get our permission to use OSB... is there a source I could cite for this? I am going to be meeting with him again this week and I want my ducks in a row (I'm sure he won't just accept the fact that "ICE, the Building Code Forum Moderator" told me so LOL). And regarding the use of V-rustic, is this something they should have to do now since the underside of the eaves of the house is totally <censored>?


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## cda (Aug 2, 2020)

fosgate3 said:


> ICE, this is exactly the information I was looking for. I have long since been told that plywood is superior to OSB for the reasons you just gave. When they delivered the materials, I noticed a sheet of OSB there in spite of the house having no OSB at all. I spoke with one of the people in charge and he first said "well, we have to go back with what's on the roof". When I told him that what's on the roof is 1/2" ply over the porch and 1x6 T&G on the rest, and that there's no OSB anywhere in the house, then he said he would make sure they did ply. I was out of town and came back when the job was done but not before anything was signed off. When I spoke to the same guy again, he made the claim that OSB was recommended, like I described in the original post. I don't like the OSB at all because it will stand out even when painted. It's in two places on the house over the eaves and looks like crap.
> 
> Regarding the fascia, we originally told them we didn't want it on there at all. It was not how the house was originally made and was added years later but only in places. We wanted it all taken down and they said they would but then didn't---but then only put new fascia boards up in some places while leaving other places with nothing or old damaged fascia. So either way, it was a bad job done.
> 
> You stated the contractor would have to get our permission to use OSB... is there a source I could cite for this? I am going to be meeting with him again this week and I want my ducks in a row (I'm sure he won't just accept the fact that "ICE, the Building Code Forum Moderator" told me so LOL). And regarding the use of V-rustic, is this something they should have to do now since the underside of the eaves of the house is totally <censored>?





Is there a written contract?

If so, any mention of what the decking material will be?


Did they just replace some decking and not the entire deck???   Once again how does the contract read?


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## fosgate3 (Aug 2, 2020)

cda said:


> Is there a written contract?
> 
> If so, any mention of what the decking material will be?


Good point. There was a written contract but I don't know if it states anything about the decking material. I will check on that.


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## ICE (Aug 2, 2020)

V-rustic is a personal choice.  They should have used 1x6 that matches the rest of the house. At this point they should replace all of the overhang sheathing around the entire house.  The wood is splintered and that's the price they pay for being so sloppy. 

You should get the insurance company on board prior to meeting the contractor.  Because the contractor lied I would fire him.  Is there a requirement for a permit?

As to getting your permission to deviate....the contractor doesn't own the house.  He can't make decisions for the owner.  I get questions from contractors and architects about substantial changes they want to make and I always tell them to get permission in writing from the owner.  I suspect that I am unique in that regard.


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## fosgate3 (Aug 2, 2020)

Thank you so very much. I will make arrangements to meet with the insurance adjuster. As for your question about permits, I was told one wasn't needed for re-roofing a house. Now I'm wondering if that's true and I feel a bit foolish for not checking. 

Thanks again.


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## e hilton (Aug 2, 2020)

fosgate3 said:


> As for your question about permits, I was told one wasn't needed for re-roofing a house.


You should call the city permit office, or look on-line, many locations have a list of when permits are required.   However, as noted earlier, there aren’t many code violations in the picture, mostly examples of bad work.  But if a permit was required but not pulled, that’s one more strike against the contract.


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## Robert (Aug 2, 2020)

I don't mind OSB on vertical surfaces but I mind it on horizontal surfaces. It turns to oatmeal when it gets wet. Another strike against it is that peel and stick membrane does not stick to it very good. I believe the deck collapse in Berkeley a few years back had substituted OSB for ply.


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## e hilton (Aug 3, 2020)

Robert ... i think you are confusing osb and mdf when you mention turning to oatmeal when wet.  Osb tolerates moisture about as well as ply.  

With regard to nails poking through ... doesn’t code require a certain length of nail penetration into the decking, and for 1/2” material i think the nails are required to poke through a little.


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## Pcinspector1 (Aug 3, 2020)

Plastic cap nail to hold the flashing on the side wall, now that's a new one...beautiful.

I'd check the staple or nailing patterns on the shingles and verify that the vent pipe flashing's are installed properly while your at it with the insurance guy.


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## Paul Sweet (Aug 3, 2020)

Unfortunately IRC 905.2.5 requires fasteners to penetrate through the sheathing if the sheathing is less than 3/4" thick.

I agree that the rest of the problems are bad workmanship and not code issues.


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## ADAguy (Aug 3, 2020)

fosgate3 said:


> Thank you so very much. I will make arrangements to meet with the insurance adjuster. As for your question about permits, I was told one wasn't needed for re-roofing a house. Now I'm wondering if that's true and I feel a bit foolish for not checking.
> 
> Thanks again.



As usual and in this case, "owner Bewary"


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## my250r11 (Aug 3, 2020)

If the OSB is rated for exposure, which I have never seen a contractor buy and pretty sure none of our lumber stores carry it in stock. OSB is not an approved exterior siding or finish material unless specifically listed for that type of use. It would be most likely be fine if had a soffit.

The wall flashing is SH!T. Not installed correctly. At minimum should have counter flashing. My biggest concern is that is TRANSITE siding which is an ACBM. Driving nails thru it now makes it damaged and classified as friable and now becomes regulated.

Most contractors don't use superior products. They use the bare minimum the code requires.

As stated already, nails have to penetrate the deck if less than 3/4.


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## ICE (Aug 3, 2020)

You guys that want the nails sticking through are not in California and if you are it's the wrong part of California.  There is a short roofing nail made for the overhangs and the nails should not penetrate.  It has been done that way for years on millions of roofs with no problems.


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## MACV (Aug 4, 2020)

OSB and plywood swell when wet but plywood pretty much dries to its original thickness and OSB doesn't unless its treated for exposure.  
Was there no specifications or standards in the contract?  Building codes generally deal with structural and waterproofing issues rather than appearance issues.  If you want something to look good you need to describe what you want.


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## e hilton (Aug 4, 2020)

ICE said:


> and the nails should not penetrate.  It has been done that way for years .


Maybe you have been doing it wrong for years.  “2015 IBC 1507.2.6 Fasteners.  ... a length to penetrate the roofing materials and a minimum of 3/4” into the roof sheathing.  Where the sheathing is less than 3/4”, the nails shall penetrate through the sheathing.“  

From the Owens Corning installation instructions: All fasteners must penetrate at least 3/4” into the wood deck or completely through the deck by a minimum of 1/4”.


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## Pcinspector1 (Aug 4, 2020)

I typically see nails through the OSB on new house construction as "e hilton" has posted. 

I can't say I see staples coming through. kinda hard to see, they tend to blend in with the OSB.


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## ICE (Aug 4, 2020)

Pcinspector1 said:


> I typically see nails through the OSB on new house construction as "e hilton" has posted.
> 
> I can't say I see staples coming through. kinda hard to see, they tend to blend in with the OSB.


We don't allow staples.


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## ICE (Aug 4, 2020)

e hilton said:


> Maybe you have been doing it wrong for years.  “2015 IBC 1507.2.6 Fasteners.  ... a length to penetrate the roofing materials and a minimum of 3/4” into the roof sheathing.  Where the sheathing is less than 3/4”, the nails shall penetrate through the sheathing.“
> 
> From the Owens Corning installation instructions: All fasteners must penetrate at least 3/4” into the wood deck or completely through the deck by a minimum of 1/4”.


There's no "maybe" about it.


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## e hilton (Aug 4, 2020)

ICE said:


> There's no "maybe" about it.


You are a complicated old coot, but i love you just the same.  First you say that they have
been using short nails on millions of roofs with no problems, and then you admit it’s been
wrong all along. At least you have an open mind.
I told my wife I had an open mind and she “yeah and your brains fell out”.


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## fosgate3 (Aug 4, 2020)

I wanted to post a follow up on this. I met with the owner of the roofing company this morning. He was very understanding and apologetic, and is going to redo all the work. He is going to have his crew come back, pull the shingles and nails from over the eaves and redo it all with shorter nails, fix a rotten spot in a roof board they overlooked, and redo the flashing. I found out that the barge rafter was never formally put into the work agreement and he was pretty ticked with his people for not only doing the work without proper documentation but also having someone do such a crappy job. He asked if I knew any contractors who could do it and I told him that I've been doing my own carpentry work for 40 years now---I only allowed this to be built because I was out of town. So he is going to sub it out to me to redo the rafter, which I will and do it correctly. As for the OSB, he assured me it was rated for exterior use so I am going to let it ride and paint with a good thick coat of paint. We all parted ways with a handshake and an agreement. I am glad I'm not in his shoes though... that's going to be a lot of work on their part to correct all of it. 

Thank you everyone for your help. It's been a long time since I've been able to come to a forum, post a question, and actually get usable information.


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## fosgate3 (Aug 4, 2020)

e hilton said:


> You are a complicated old bastard, but i love you just the same.  First you say that they have been using short nails on millions of roofs with no problems, and then you admit it’s been wrong all along. At least you havevan open mind.
> I told my wife i had an open mind and she “yeah and your brains fell out”.



The point you make here reminds me of how we didn't find one nail penetrating through the sheathing in all the Craftsman style houses we could find in our neighborhood. We walked the streets and found 20-something houses with newer roofs...none of them had nails protruding or had any extra material installed under the roof deck to hide nails. I don't know how they are doing it if they aren't using short nails.


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## ICE (Aug 4, 2020)

Every now and then, someone will blast nails through the plywood and it happens with lumber too.  The owner is crestfallen that he hired the guy.  The owner wants me to make it right.  The guy wants a code section.  I make one.  Then a supervisor reverses the correction....but not everyone is smart enough to go to the office.

And by the way, there’s no code that requires the contractor to remove the shingle debris from rain gutters either.  Supervisors don’t bother telling me about those contractor complaints.

You can see the mess in the picture and think that it’s okay? I have had cases where the owner hired another person to cover the underside of the rafter tails. 

Did I mention the long history of using short nails with no problems.  It’s not my fault that the code needs my help.


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## north star (Aug 5, 2020)

*@ ~ @ ~ @*

***fosgate3**,*

We are glad that this Forum could help you with your application.
Now, we would like to request your help !.......For this GREAT
resource to be able to continue takes commitment & resources.
Would you consider becoming a regular member by purchasing
a subscription to this Forum ?......By doing so, you would become
what we call a Sawhorse........If you are interested in doing so,
please send a Private Message to *** jeff546 *** [ < - - - the Forum
owner  ], and discuss payment options........I believe the current
rate is $60.00 for a 2 year subscription.

Thank you for your consideration, and for coming to this Forum.

*P.S.*  Please take pictures of your house after the re-do and
come back and post `em here.   

*@ ~ @ ~ @*


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## e hilton (Aug 5, 2020)

fosgate3 said:


> we didn't find one nail penetrating through the sheathing in all the Craftsman style houses we could find in our neighborhood. .


Maybe the older houses use full dimension decking.


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## Pcinspector1 (Aug 5, 2020)

ICE said:


> We don't allow staples.



Don't allowed by a code amendment, manufacture installment instructions doesn't allow or other reason?




ICE said:


> The owner is *crestfallen* that he hired the guy.



Crestfallen, is now on my board of new words, had to look that one up!


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## ICE (Aug 5, 2020)

Pcinspector1 said:


> Don't allowed by a code amendment, manufacture installment instructions doesn't allow or other reason?



I don’t know.


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## Pcinspector1 (Aug 5, 2020)

I'm not seeing install instructions allowing staples. 

Have the codes changed to disallow staples? 

Seems like the UBC allowed them?


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## ICE (Aug 5, 2020)

Pcinspector1 said:


> I'm not seeing install instructions allowing staples.
> 
> Have the codes changed to disallow staples?
> 
> Seems like the UBC allowed them?



_R905.2.5 Fasteners. Fasteners for asphalt shingles shall be galvanized steel, stainless steel, aluminum or copper *roofing nails*, minimum 12-gage [0.105 inch] shank with a minimum 3/8 -inch-diameter head, complying with ASTM F1667, of a length to penetrate through the roofing materials and not less than 3/4 inch into the roof sheathing. Where the roof sheathing is less than 3/4 inch thick, the fasteners shall penetrate through the sheathing. _

No mention of staples.  In the section for wood shake and wood shingle the staples are mentioned and approved.


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