Painting - Painting over wallpaper

I have 80 year old plaster walls. It has been a real pain to strip the painted wallpaper off of them and then repair all of the cracks and repaint. I have one small room that has new unpainted wallpaper on it however. Since the paper was put on well and I can't see any cracks, it would be nice to simply paint over the wallpaper.

Will I regret doing this later? I hate the idea of stripping the paper off only to find a bunch of cracks in the walls I have to fix, which will then show up some once I repaint, but at the same time I want to do this right. And if I do paint over the wallpaper, what is the best primer to use? Many web sites say to use oil based primer since water-based soaks up the water in the glue and screws it up, and I've also seen places that say to use something like Zinnser Gardz.

Basically I'm wondering how common it is to paint over wallpaper and what others here think about it.

Thanks for any help!

Basically I'm wondering how common it is to paint over wallpaper and what others here think about it.

I think it's somewhat common among DIYers, but not Pros
The proper way is to remove the wall covering
It's usually not a good idea to paint over it on many levels

That being said, sometimes we have to make adjustments to the SOP

I don't think I've ever stripped covering over plaster, so I don't want to comment on that
Most plaster around here was replaced long ago, or as part of a remodel, before I paint

Mind if I hang around and see if anyone else has stripped paper off plaster?
:)

Sometimes the wallpaper is what holds old plaster together. The two biggest reasons not paint over wallpaper are

makes it a lot harder to strip if you need to at a later date.

the walls often don't look as good as they would over properly prepared plaster/drywall.

I spent several weeks with a paper scorer, spray stripper, fabric softener in a spray bottle, and a steamer stripping the paper from my stairway. I'm not sure if the plaster hadn't been properly sized or what kind of wall paste was used 70 years ago, but I could not get the original paste off of the walls. The walls were in terrible looking shape but structurally sound. The original wall paper must have been fabric, as the glue had a gauze-like texture to it. I ended up skim coating the entire stairway to cover the gauzey texture. I ended up with a very random texture which after a good coat of primer and 2 coats of quality paint, it looks fabulous. The stairway was a labor of love for me :wall: . Start to finish it took two months of hauling scaffolding in and out, using a steamer in July during a 95 degree week but I am happy with the results :D .

I was tempted to just paint over the paper, it would have been much easier, it probably would have turned out all right, but anything worth doing is worth doing right.

I painted over wallpaper in a large kitchen last year and so far, great! I followed some other people's advice which was: degrease and clean the wallpaper, glue down loose seams, smooth out ruffled seams or tears (used spackling I believe) to get a smooth even finish in damaged areas, thinned down some Kilz and painted a base coat, and then painted with regular latex paint. Looks great - so far.

I took this route because after stripping the wallpaper from the bathrooms (15 years old), my walls were a total wreck which resulted in a huge headache.