Tear off or cover over

[Andrew Kerr]

All,
I have a quad I am updating with a new roof and new siding. What is the preferred method for putting on new vinyl siding? Do you go over the existing siding or tear off the old stuff then start new?

Some of the quotes I got from contractors have an insulation board that is put down over the existing wood style shingle siding, then have the new siding go over top. Then others say it is best to rip off everything and go down to studs/OSB, then put on new OSB where needed, then do a wrap then finish with the new siding.

Any negatives to either way?