New roof decking over old questions


Hi all, I’m not a roofer but have construction experience. I’m having a re-roof done on a circa 1960’s house built with trusses on 24" centers. The original decking was 3/8 plywood and is ok in most places but of course a bit spongy between supports. The roofers replaced any bad plywood and then re-decked it with 1/2" osb on top of the 3/8. They ran felt yesterday and I got up in the attic this AM to check… as I was afraid of, they missed the trusses in a lot of places including many of the end seams. I’ve stopped any further work for now but am wondering what the best fix is for this. The roofer is first saying that this is fine, they do it all the time and when I’m not accepting that he’s suggesting they can fold the nails over or put screws in as well or put a 2x4 under the seams and re-nail it to that. All of these solutions seem questionable to me and I would expect to raise a red flag with a home inspector even if they were to work on a practical level.
These guys do have a permit (just says “reroof”) but I haven’t called the building inspector yet. Hoping to arm myself with more information first…
What are the experts opinions on this situation? What would you do?


We’ve hashed this problem, many times here. First off, you made a mistake putting sheathing over sheathing. That 3/8, though rated for 24" centers, sags. I bet it has a 1/2"dip in some places, between the trusses. Now you put 7/16 OSB on it and it planes outsmooth, but that 1/2" dip is there. When the shingles go on, all those areas that have an air space, the nail will push the 3/8 down and keep tension on the nail. Mark the date. In as little as 3 months, you will have fish mouths,(backed out nails) all over the roof.
As far as the decking nails missing, that’s another issue with not seeing the truss.
I’ve given you my opinion. Your into this thing already, so you’ll have to decide. Sorry it happened to you, but on this one, my opinions are fact.


:frowning: Well you’re right, I’m into it now and as long as what they’re doing passes code, I don’t see how I will change it. Apparently the building dept will allow it (even with the vertical seams not landing on the trusses) if they go back and put 2x4 blocking at the seams and re-nail through that. It’s not my choice of how it gets done but I really can’t argue it. If what they’re doing passes code it meets the terms of our agreement.


If they support the floating seams it’ll be ok, not a fan of plywood over plywood but it’s done all the time.


Rooferama is right about what happens when nailing new sheeting over 3/8s.
Especially noticeable with 3-tabs roofing.
Id like to add that i have gone back and knocked down the roofing nails that poked back up
And didnt have further problems.
One roof, i had to go back twice.


How did you hear that it is up to code. I would think you need an engineer sign off for that to be true. Who’s idea was the 2nd layer?


The right job would be to remove everything and install 5/8 plywood to bring it up to code. And protect your investment.

I Would personally never I install plywood over plywood, but at this point you pretty much just have to have them fix it.

A 2x4 running parallel to the rafters will not cut it where the seams don’t land on rafters. They will need to install solid blocking perpendicular to the rafters under each break that is not on a rather. I would recommend 16" on center but 24 would probably meet code.

I would also have them run a row of 1 5/8 screws from top to bottom every 12" centered bewtween the rafters to suck the two sheets together. With 7/8 of plywood you need to make sure they are using 1 1/2" minimum nails to install the shingles to make sure they fully penetrate both layors of plywood, I personally would use 1 3/4.


RooferOhio, you’re right. They are now getting a revised permit because their original permit was only for a simple re-roof. Since they were also extending the eaves, they also need a survey to show that there’s no encroachment on the setbacks. Of course there is no survey available so the job is turning into a bigger boondoggle. I talked with the building inspector today and he hasn’t ok’d the 2x4 blocking under the vertical seams as the roofer said he did… he tells me they have to come in to get their revised permit and then they can discuss how it’s going to be done. It seems that they might need an engineer’s stamp on the whole thing too. I hope these guys don’t go broke trying to do this job and leave me hanging.


I would give them a chance to make things right. In the meantime time I would have a contingency plan in place in case things go south.

To over analyze: Did they say the building department would be ok with the 2x4 fix, or did they outright lie and say the building department okayed the 2x4 fix?


I don’t have a choice right now other than to give them a chance to make things right but that’s what I’d do anyway. I like these guys and we’re not at each other’s throats (yet) so I’d like to see it resolved with them. The biggest problem I have with the situation right now is the timeline. It looks like we now have to get a survey and go through a plan review probably with an engineer’s stamp. I’m thinking we lose at least another week there. That can’t be helped at this point.

We’re both talking to the same plan reviewer, a guy named Ben. I thought the roofer said that Ben said the single 2x4 would be acceptable but I acknowledge that maybe I misconstrued that point. Today Ben didn’t seem to think he had said that. Also possible that the roofer thought Ben said that. I’m not ready to call someone a liar just yet.


He puts new decking on and extends the eves for you because you asked which is not in his official scope of work.
Then you call the building department and run your mouth…
Nice… real nice.
Now the roofers have packed up and are now working on someone else’s roof…
Oh well, hope it doesnt rain in the next month or two.


Did the cover your roof with underlayment at least? I avoid jobs like this just for that reason. Roofs open too long, to many headaches


There is felt down on the roof.

Roof_lover, you have no idea of the details and shouldn’t jump to conclusions. These guys do other work than roofing… the eave extensions and redecking the roof are well within their scope of work. I had several conversations with them before calling the building inspector and let them know that I wanted to do that to clear up what passes code, etc. They OK’d my making that call ahead of time.
Maybe next time you should learn the facts before you “run your mouth”.

I appreciate everyone else’s input.


They pulled a permit.
Let them handle the inspector for their work.
You shouldnt have called the building department running your mouth.
That is why your job is abandoned with no real time frame in sight of completion.
A week you think?