How should I handle old wallpaper over top of lead paint?

Question

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?

Answer 1

Definitely read up on the EPA 'renovation repair and painting' rule.

Option #3, the 1/4" drywall, is likely to produce the best and cleanest results, at the cost of loss of room space and alteration in the look of all your trim. You'll have to extend all outlets also. Of course that sounds suspiciously like what happened last time. Eventually your room will be solid wall covering with no center.

Option #4 sounds attractive if that texture on the wallpaper will really hold the joint compound. I'd run a test with and without the primer/sealer. Remember worst case here it cracks later and you redo it all with #3.

Answer 2

For posterity's sake, in the end after some testing we decided to go with approach #4 (the skim-coat).

We did one layer of Zinsser Gardz sealer over everything, and then we used this skim-coating process, doing multiple coats of thinned-out lightweight joint compound applied with a roller and a rubber-edged 14" wide "Magic Trowel". That process gave us a pretty smooth surface, even without any prior experience skim-coating. We did two coats followed by some touch-up with spackling compound. In between the first and second skimcoats we also taped and mudded the wall and ceiling corners, where previously there had been trim covering over the crack at the edge of the wallboard; we didn't want trim in all those corners.

It's now been a week since we applied that surface, and we've primed and painted it. So far so good - no cracking or any other issues. Looks remarkably good, including the corners; you wouldn't think twice about it unless you inspected it quite carefully. There are a couple spots where, before we painted, you could see a barely-perceptible texture from the wallpaper showing through with the light at just the right angle. I haven't seen that since painting; if we'd been less impatient and done three or four skim-coats instead of two we probably could have gotten rid of it entirely.

Drywall probably would have worked fine, too, although we were concerned about possible waviness with the thin 1/4 stuff (maybe applying with construction adhesive rather than screws would have helped that). In the end I think the skim-coating approach was a bit cheaper, and really no more difficult - probably took a bit longer due to waiting for each coat to dry. The surface is plenty good enough, and we don't have to cut our trim or extend our outlets.

Hope this helps someone in a similar situation!