Re-roof: new OSB deck over wood shake/shingle

[Joe Funderburk, CMI]

Anything to prohibit that or should the shingles/shakes have been removed?

[James F. McKee]

you're joking right?

[Jeffrey R. Jonas]

Wasn't there a discussion here a few weeks ago about this? I could of swore you were part of it.

http://www.nachi.org/forum/f16/more-...al-code-61246/

You supplied the answer. Now you question it?

[Robert Ernst]

Wow, that's pretty bad. Call your local building department and ask them. If a new roof was put on they should have had a permit right?

[Joe Funderburk, CMI]

Originally Posted by jjonas

Wasn't there a discussion here a few weeks ago about this? I could of swore you were part of it.

http://www.nachi.org/forum/f16/more-...al-code-61246/

You supplied the answer. Now you question it?

That post dealt with multiple layers of ashphalt shingles.

My question in this thread is, can you hang your hat on anything that says a new roof decking over wood shingles or shakes is wrong.

[Jeffrey R. Jonas]

Originally Posted by jfunderburk

That post dealt with multiple layers of ashphalt shingles.

My question in this thread is, can you hang your hat on anything that says a new roof decking over wood shingles or shakes is wrong.

Am I reading this wrong? Does this not apply to what you are asking in this thread?

From the other thread...

Code:

"R907.3 Re-covering versus replacement. New roof coverings shall not be installed without first removing existing roof coverings where any of the following conditions occur:

1. Where the existing roof or roof covering is water-soaked or has deteriorated to the point that the existing roof or roof covering is not adequate as a base for additional roofing.
2. Where the existing roof covering is wood shake, slate, clay, cement or asbestos cement tile.
3. Where the existing roof has two or more applications of any type of roof covering.
4. For asphalt shingles, when the building is located in an area subject to moderate or severe hail exposure according to Figure R903.5.

[Joe Funderburk, CMI]

The way I read that code, is that it prohibits the installation of asphalt shingles directly over other types of shingles in certain situations.

My question here is, again, is there anything that absolutely prohibits the installation of OSB sheathing on top of wood shingles or shakes. In that case, the subsequent layer of asphalt shingles would not be a direct installation over the wood shake/shingle.

[Jeffrey R. Jonas]

Originally Posted by jfunderburk

The way I read that code, is that it prohibits the installation of asphalt shingles directly over other types of shingles in certain situations.

My question here is, again, is there anything that absolutely prohibits the installation of OSB sheathing on top of wood shingles or shakes. In that case, the subsequent layer of asphalt shingles would not be a direct installation over the wood shake/shingle.

I believe this is one of many examples where you need to go with the intent of the code, and not be so literal.

I'm done here.

Next!

[James E. Braun, CMI]

The same reason multiple layers of asphalt shingles are not allowed is the same reason sheeting should not be put over shakes. The answer is: The roofing material has to breath.

[Christopher Currins]

Originally Posted by jbraun

The same reason multiple layers of asphalt shingles are not allowed is the same reason sheeting should not be put over shakes. The answer is: The roofing material has to breath.

Also weight and fire issues.

[Brian A. MacNeish]

Originally Posted by jbraun

The same reason multiple layers of asphalt shingles are not allowed is the same reason sheeting should not be put over shakes. The answer is: The roofing material has to breath.

Asphalt has to breathe......where are the lungs???

Usually the problems are attachment of new shingles adequately to the wood sheathing, extra weight on framing, curled/clawing old shingles not providing a flat surface for shingles to lay flat and seal down.

[Joe Funderburk, CMI]

Besides the extra weight, I see the primary issue being that there is no way to ensure that the sheathing fasteners actually hit the structure. The nails might simply have been driven into wood shakes/shingles. How would the guy driving the nails know what he hit? The right kind of wind, and it's all gone.

[Marcel R. Cyr]

I don't need no code book to tell me that installing a roof sheathing on top of wood shakes is wrong or right. It is totally assinine.
How in the world would you maintain a smooth plane on the roof on top of wood shakes. Those are hand split and none are of the same thickness.
Now I know there are idiots out there that would do this type of work, but that is because they do not know anybetter.
And the way the code is written, should cover this type of overlay on an existing roof.
Like Jeff said, the intent of the code is clear to me to prevent this, plus the AHJ would have the last word on this with a permitted work.

[Tim Spargo]

Originally Posted by mcyr

[COLOR=blue]I don't need no code book to tell me that installing a roof sheathing on top of wood shakes is wrong or right. It is totally assinine.

Agreed. If someone told me it was OK, I still wouldn't hang my hat on it. At best... a lumpy, unprofessional mess. At worst, an over loaded, deficient roof installation.

[RUSSELL SHUEY]

If an engineer ok's it, I'm good. But you won't find an engineer dumb enough to ok that.