What's Under The Wood Siding

72chevy4x4

I'm getting ready to get a job on a ranch house covered w/ wood lap siding. Under the siding is styrofoam board...not sure what is under the foam board. The house is around 25-30 years old. I've bid the job with removal of the siding, planning on leaving the foam board-do you 'think' OSB is under the foam board? If OSB/plywood is not under the foam board, would the course of action be to strip the foam board and install OSB? If that were the case, how should I install?

I'm thinking that removing the siding would make for a cleaner install around windows and door b/c the j-channel won't stick out as much. Is that a good practice?

theroofinggod

if the siding is in good condition why take it off,just go over w/3/4"rigid insulation,and build out the window and door casings w/plywood or pine depending on what you neede to achieve,old clapboard can have nothing under it,if you opt to remove use plywood instead of OSB --you`re better off going over in that situation,and the building will end up much better insulated

mdshunk

You're not so far from me. I know in my area, houses of that vintage had the Celotex right on the studs. It was generally only the corners and near large openings where they used plywood, and filled in the field with Celotex. There may well be nothing under that foam board other than the stud bays.

theroofinggod

exactly what I`m saying,clapboard is typically stud nailed for that reason