Can siding be used as sheathing?

I know this sounds like a strange question, but hear me out. There is an area of my house that is getting new siding, either hardi board or cedar bevel, and it currently has plywood panel siding on it. Can I treat this plywood siding as the sheathing and put the new stuff over top, or do I need to take it down and put up "real" sheathing. Isn't it basically the same thing? I would love to hear some opinions on this one

Thanks
Chris

chris, if it`s plywood and in good shape as in no rot, and you don`t mind adding extention jambs to the doors and windows then sure...go for it. tod

I think it would be fine. Just keep in mind, the nail spacing for sheathing is a lot more rigorous then most people think. It is rigorous, or in other words, nailed something like every 8 to 12 inches because that is what gives your framed structure rigidity. You should check your local building codes however. I might go ahead and plunk some more nails in it, or at least make sure it is nailed very well, then go ahead and toss up your siding.

It is interesting to note that my Uncle built one of his many houses using log siding. He did not both using any sheathing behind that home, instead using the rather thick siding as sheathing and siding both. Myself I would not do that. In your case though, I think that would be fine.