We removed a layer of thick textured wallpaper on a wall in the dining room of our 1959 split-level; it came off very easily in large strips. Unfortunately underneath it is a layer of much older (1970s?) and much uglier wallpaper which comes off only with extensive elbow grease, and immediately under that (we've only removed a small area so far) is a layer of flaking leaded paint (verified both by small-squares flaking pattern and with a home lead test kit). To add additional complexity, all of this is on top of some kind of 1/2in composite wallboard; we can only access a very small area of what's behind the wallboard, but it seems to be a plaster wall, also with leaded paint on it.
Our goal here is a flat paintable surface, and (much more importantly) not lead-poisoning our children.
Options we are considering:
1) Hire lead-abatement professionals to strip everything down to the plaster, and then see what we need to do from there. We can't really afford this.
2) Try to pry off the wallboard so we can see more fully the condition of the wall behind it. This is tempting because it removes more cruft from the wall, but it has some downsides: It will certainly result in additional flaking of the lead paint on the wallboard, as the pieces of wallboard separate. Depending how the wallboard is attached, it may be quite difficult to pry off and result in pieces of wallboard still stuck to the wall, which may be quite hard to get off without disturbing even more lead paint. And lastly, we don't know why someone put up the wallboard in the first place, which leaves us concerned about the condition of the wall we might find underneath it. (A third of this wall was an extension on the house at around the same time the wallboard was probably put up, so for the last eight feet we aren't even sure there will be anything at all behind it.)
3) Hang a fresh layer of 1/4in drywall over top of everything.
4) Cover the wall as-is with a layer of Zinsser Gardz to seal everything in and prevent reactivating any wallpaper glue, then skim-coat with thin layers of joint compound (using a roller brush and squeegee trowel), prime, and paint. ("As-is" means mostly covered with the old wallpaper, which is in quite good condition, not peeling or bubbling at all and firmly stuck - also its tough wallpaper with some kind of fabric weave in it. It also has a bit of glue residue on top of it from the wallpaper we already removed.)
Currently we are leaning towards option 4. Is this a crazy idea? What would you do?