Siding a Timber Frame

We bought a 20 year old Timber Frame last year. We're looking at replacing the clapboard siding. When we had an experienced contractor over he was stumped. It isn't too clear what the existing siding is nailed to - if anything!! No wonder why it's cupping and in such bad shape. We popped up a couple of clapboards and all we find is sheet insulation, no sheathing, nothing.

Our next step is to remove a section of siding to get a better look at what's underneath. We're also contacting local Timber Frame companies to get their input, but from what I've heard they have 2 year waiting lists for houses and I can't imagine they'll be too interested in a siding job...

Does anybody here have input on what we could expect to find under the siding? If there in fact is nothing there, what are the ramifications of installing a plywood sheathing? What else could be done?

Thanks for any input you might have.

It sounds like whoever sided your house didn't use nails long enough to reach any sheathing. Hopefully when you remove this sheet insulation you'll find some. There should be some 'nailers' there somewhere. If not then these are what maybe needed to attach your new siding to. Good luck, and let us know what you find and how you solve it. You could ask these companies you've been talking to, to refer you to a siding company who has experience in siding timber frames. Jim