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

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

you’re joking right?

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

You supplied the answer. Now you question it?

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?

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…

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.


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.

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.

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.

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. :slight_smile:

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.

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

I’ve been seeing some pretty ‘dumb-arse’ engineer’s lately. It may be structurally ok, but I still wouldn’t “hang my hat on it”!

How about shingles on a steel roof And tar on the chimney

Steel roof new shingles and asphalt.jpg


The roofer has agreed with my ‘recommendation’ to take it all off, down to the rafters, and re-do it. :slight_smile:

As an HI or an AHJ?