# Sheathing over existing sheathing question



## AtlanticWBConst. (May 12, 2006)

Sunseek said:


> Hello,
> 
> First of all thank you to anyone who is taking time to read this.
> 
> ...


Very uncommon practice. Standard procedure is to remove damaged sheathing and replace it, especially if it is moist and damaged/rotted.

Would I do it on my own home: no.

Can it be done that way: yes.

Is there some other reason that he may be doing it this way: Possibly, we do not know all the details about the age and construction of your home and your roof. There could be other factors that are involved that he may feel that this is the method to go at...

Other posters may have some further input....


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## Sunseek (Apr 18, 2007)

AtlanticWBConst,

Thank you for your input. He's got about 1/4 of the roof double sheathed with felt paper down.

I'm not sure what to do at this juncture. Either I plant my feet and make him start over or live with it. 

What confuses me is he knows I'm particular and will be calling him after the fact if something doesn't look right. Of all the things I tried to learn to make me an educated buyer this was not one of the topics.


James


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## Ed the Roofer (Jan 27, 2007)

I do not usually jump down another contractors neck, but that is totally wrong.....unless that is what was stated in the written contract details.

Were they explicitly detailed? Is this what you and the contractor agreed to?

Or, was the issue of potential decking replacement/recoverment never addressed, or very vague in the details?

In 29 years of roofing, I have only run into this scenario 3-4 times.

Each time it cost the homeowner a significant amount of additional money to then do a tear-off of an extra layer of decking.

Why? What happens and is this wrong? 

Yes, it is absolutely wrong, because how do they ensure that the nail pattern is properly hitting and sinking deep enough into the rafters or trusses?

They can not see where they are located, so they are possibly closely following the old nail pattern on the delaminated soft existing deck sheathing. How do they know if they miss? They don't!

What, specifically was in the contract?

Would you install a brand new carpet over the old rotting carpet if this were the situation.

Stop! Do the job the Right Way. You only have one chance to do the job right the first time. Any time after that it is just a repair of a defective system.

Call up the APA, American Plywood Association, and see what there advise is.

Call up Certainteed Corporation or which ever brand of shingles you are having installed, and see what there answer is. 

Will roofing over multiple deck sheathings, with the underneath base deck sheathing already deteriorating qualify for the manufacturers warranty specifications?

Ed


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## Sunseek (Apr 18, 2007)

Ed,

Thank you for your candor. In the quote it was stated that any damaged parts of the existing plywood would be replaced. At that time he did not suspect that the damage was going to require more than a sheet or two for the entire roof.

After he started tearing off shingles he told me the problems and explained the sheathing over existing sheathing and how I have no down side to this approach. The price jumped $1500 but I understand that if he's doing it right. (Now I know what right is)

He will be installing Elk shingles. Elk will be my first phone call. 

I enjoy learning and watching people who are skilled in their trade and take pride in a job well done. Experiences like this detract from that.

I have his quote but he has nothing signed from me. He also has just over $3,600 of my money.

Before this is all over I may need just a bit more input. I sincerely appreciate the help.

James


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## roofboy (Jan 18, 2007)

Hello,

When we replace bad sheeting he have to make sure you "kill" the rot or it will continue. If they did not use a rot killer then the problem will not go away. I do not remember what we use but we spread it on the damaged areas after cutting all the rot out.
I know that you didn't say anything about rot and I am not trying to scare you but if the plywood is indeed moist or rotten as AtlanticWBConst. stated then the rot will continue.

Keith


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## AtlanticWBConst. (May 12, 2006)

Ed the Roofer said:


> I do not usually jump down another contractors neck, but that is totally wrong.....unless that is what was stated in the written contract details......
> In 29 years of roofing, I have only run into this scenario 3-4 times......
> Yes, it is absolutely wrong, because how do they ensure that the nail pattern is properly hitting and sinking deep enough into the rafters or trusses?
> Ed


That was my 'initial' reaction too.....


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## handy man88 (Jan 23, 2007)

How can you get a nice smooth flat roof if you're putting OSB over existing material?


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## Ed the Roofer (Jan 27, 2007)

Sunseek said:


> In the quote it was stated that any damaged parts of the existing plywood would be replaced. At that time he did not suspect that the damage was going to require more than a sheet or two for the entire roof.
> James


 
That phrase, if entirely accurate states that damaged plywood would be *replaced!* Not layed over the top.

In the Chicago area, we replace rotted decking at $ 2.00 per square foot, (Home Depot is at $ 3.00 per square foot, btw), which translates to $ 64.00 per full sheet replaced. Prices in a heavily non-union area of Wisconsin will probably be much cheaper.

We never, ever use OSB board, but that point is up to debate amongst many contractors still. But, the good contractors do not try to cut corners by using an inferior product!

I was just in the Dells 3 weeks ago and my parents live in Green Lake.
What part of Packer-Land are you from?

If the contract stated he would replace decking using "Plywood", then he should be using plywood, not oriented strand board, (OSB).

Ed


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## Ron6519 (Mar 28, 2007)

This is an ill advised practice with questionable materials. Personnally, I don't ever use OSB. This is just my preference. But the covering up of marginal material is stupid and lazy and an unnecessary expense.
Not quite as bad as putting homesote board over a slate roof and then installing a 3 tab asphalt roof. But still...
Now, that was a Kodak moment.
Ron


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## Ed the Roofer (Jan 27, 2007)

Check out this link. It is a California building department code, but it seems to be very precise.

http://64.233.167.104/search?q=cach...plywood+roof+decking&hl=en&ct=clnk&cd=3&gl=us

Ed


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## Ron6519 (Mar 28, 2007)

I've seen roof sheathing 3/8" and 1/2" thick on various , developement roofs. In that case I would add another layer of sheathing to the roof. I would not add it over bad sheathing. The bad stuff would need to be removed first.
I read the link on the California building code. I do not understand the thought process involved with those guidelines. I think it's stupid to throw a layer of sheathing over any roofing material. Around here, if they come accross cedar shingles, they remove them and put sheathing over the spaced boards. 
I will add that I am not a roofer. I'm a remodeling contractor.
Ron


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## Sunseek (Apr 18, 2007)

Ed,

Well what a day. I was hoping Elk was going to make things easy for me, but they didn't. The Field Support tech did not have any problems with my situation. It was early in the day and I had other battles to fight so I left it at that with Elk.

Long story short they ripped up the new OSB and old plywood. I spent my day on the roof having the contractor point out to me that the existing plywood had just been baked, not wet or showing signs of rot.

The hard part is after that was done I felt as if I should remain on the roof and make sure they weren't making me pay for having this done the right way. Not that I have much of a clue but I try. Bought the guys pizza and soda to try and at least get the workers to like me again and put some effort into my roof.

All in all I must say I have new respect for all of you in this business. One 12 hour day on my roof and I'm ready to take a vacation. The weather was only 65F, I can't imagine high humidity and 95F.

I have several other thoughts to pass on but I'm going to save those for tomorrow. I'm going to bed.

Thank you everyone!

I'm in Green Bay Ed, where in IL are you? My family business is custom interior / exterior doors and most of our work is the north shore. I owe you a beer next time I'm down.

James




Ed the Roofer said:


> That phrase, if entirely accurate states that damaged plywood would be *replaced!* Not layed over the top.
> 
> In the Chicago area, we replace rotted decking at $ 2.00 per square foot, (Home Depot is at $ 3.00 per square foot, btw), which translates to $ 64.00 per full sheet replaced. Prices in a heavily non-union area of Wisconsin will probably be much cheaper.
> 
> ...


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## AtlanticWBConst. (May 12, 2006)

Sunseek,

I'm glad that things all worked out for you.


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## Ed the Roofer (Jan 27, 2007)

The reason for the lack of response from Elk, according to what I just read elsewhere, is that they just laid off all of their manufacturers representatives via teleconference call.

Elk was just merged/bought out by GAF Roofing Corporation for your information.

I've been to Lambeau for 3-4 Bears/Packers games. The infamous "Instant Replay" game was one when Majewski (sp), was the quarter-back. I am North West suburbs of Chicago, near Elgin IL.

If you ever need a flat roof done, talk to Don Warner of Badger Land Roofing right in your town. He used to be a quality control inspector for Duro-Last single ply rooing membrane installations and was a nice and knowledgeable guy, as I remember from about 20 years ago.

Ed


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## parkerfairfield (Apr 28, 2007)

Ed the Roofer said:


> Check out this link. It is a California building department code, but it seems to be very precise.
> 
> http://64.233.167.104/search?q=cach...plywood+roof+decking&hl=en&ct=clnk&cd=3&gl=us
> 
> Ed


I love this line in that document:
Dry *tot*, broken, or termite damaged roof sheathing and framing members shall be removed and 
replaced.


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## troubleseeker (Sep 25, 2006)

I don't understand why he just doesn't remove/replace the few bad sheets. After seeing your climate loaction, I would be concerned about creating a moisture trap between the layers, as the glue in the existing plywood creates a vapor barrier technically. If you have warm air leakage into the attic, and it reaches the cold sheeting, there is going to be the potential for condensation. IMO this does not sound like something I would want.


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