Question about Bathroom renovation and repainting

[ear3]

So I'm continuing on with the home renovation project I started this summer.  Finished the master bedroom and moving now to the bathroom.

Let me just preface everything by saying that I'm very much a novice when it comes to painting.  With that being said, I have a question about removing existing paint and then applying a new coat.  First some background:

The house is from the 1930s, and has plaster walls.  Other than hairline cracks and some paint flaking in a few spots, the plaster is in good shape -- still keyed to the lathe and all -- so my objective has been to preserve it.  Maybe four or five years ago, before I took over full ownership of the house, there was a plumbing incident in the upstairs bathroom (right above the one I'm working on) when the plumber tore through one of the pipes while snaking it -- don't ask.  Anyway, we had a guy come in and redo the plaster in the section of our bathroom ceiling that had to be torn out to get to the affected pipes.  In the process he repainted the entire bathroom and trim.

He seems to have done a good job with the plaster, as it is still solid.  But within a year of the job being completed the paint started to flake in various spots.  The flaking has only gotten worse, and so I can no longer ignore it and am going to redo the bathroom.  As you can see from the pictures below, this is not the type of flaking you get from the plaster settling, but it's almost as if there wasn't a primer put down over the previous layers of paint (it's hard to believe the contractor would have been that stupid/lazy, but who knows).

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When the room fills up with water vapor from the shower (it's not terribly well-ventilated), some additional bubbling will appear in areas that have become porous, though which have not begun to flake yet.  This bubbling disappears once the vapor has subsided.

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So the question(s): First: what is your best-guess diagnosis of the problem?  No primer?  Inferior paint/primer combo for humid conditions?  Second, the solution: I obviously need to scrape off all the flaking as well as the bubbling sections.  Since there is 80s years of paint buffering the plaster from the existing top coat, I was thinking of just using my ROTEX with some 80 grit Brilliant or Granat, and hooked up to my CT26, sanding enough to get off the first layer, but not so deep where I'm going to be cutting into the underlying layers or the plaster itself.  How much of the top coat should I sand off?  As much as possible, or only those areas where there are visible problems?  [UPDATE: plaster is clean of asbestos, but there is certainly lead paint somewhere among those layers]

After that, I was going to apply an oil-based primer like Kilz, and then an eggshell latex top coat of some kind.  Any recommendations on the type/brand of primer or the top coat, keeping in mind that these are plaster walls with 80 years worth of paint and it's a humid environment?  Thanks in advance for any guidance.

 

[tjbnwi]

With the age of the home there is most probably lead and asbestos in the paint/plaster. Look up RRP guidelines for safe working practices with the lead. Asbestos needs to be handled properly also.

That said, scrape all the loose top coats to determine how much is affected. You may find an entire layer scraps off easily. You must get down to a well bonded surface.

Use Gaurdz instead of Kilz.

Tom

 

[ear3]

Thanks for the advice.

When my father took over the house from my grandfather 25 years ago, we did have asbestos testing done.  It turned up in the pipe insulation in the basement, which necessitated a major removal project, but the plaster came back clean.  Lead paint is obviously a concern, though -- I suited up pretty well and wore a space-age dust mask when I was redoing the master bedroom, even though that was just minor scraping before doing a skim coat.

Are you saying then that I shouldn't sand because of the dangers from lead, and just stick to manual scraping?  Looking over the RRP guidelines it says that sanding is permitted provided it's hooked up to a HEPA vac, which would include the CTs.

Thanks for the rec. on the primer.

 

[tjbnwi]

I pointed to the RRP rules because it was easier to have you read the accepted procedure rather than me type the info.

You are correct, all of the new CT's except the 36 AC are Full HEPA certified and RRP compliant.

I scrap off as much as I can before going to the sanding stage, easier and faster than sanding in most cases. After all the loose material is removed, I fill the low spots then sand. If you have exposed plaster wipe the area with a damp cloth, prime it with Gaurdz then patch. Sand as needed. Watch the patches as you sand, they are softer than the paint easy to remove to much from the patch. At times I will sand, then prime a patched area and refill. Makes it easier to blend.

Tom

 

[ear3]

Thanks so much for the pointers.  I have some houseguests with young kids coming in for Thanksgiving, so I'm going to hold off until after that's over so I don't accidentally poison the little ones with lead.  As everyone's out shopping on Black Friday, though, I'll be scraping paint!

 

[Dan Clark]

Edward,

I remodeled (rebuilt) my master bath.  Depending on the extent of your remodeling, a bathroom remodel can easily be one to two orders of magnitude more difficult than remodeling a bedroom. 

The biggest question is: What did the bathroom look like BEFORE it was repainted?  Did it have those bubbles?  Is this the result of poor ventilation?

And, are you SURE that the plumbing was fixed correctly?  Is the plaster cool to the touch in the spots where the bubbles are occurring?  ("Cool" may equal "damp".)

Regards,

Dan.

 

[ear3]

Dan,

Yeah -- I considered that it might be due to continued leakage when the problem first started.  But here's why I think the problem is due to the misapplication or poor selection of paint by the previous contractor.  There has never been any problem like this in that bathroom over the 25 years I've lived in the house.  Moreover, I've scraped off some of the affected areas already (as in first photo) -- the underlying surface of previous layers of paint is absolutely fine, no coolness or distortion.  Again, I'm not an expert in this stuff, but I did fix a moisture problem a couple of years ago in one of the other rooms, where some water was leaking from the window.  You could tell by the distortion in the underlying layers of the paint that moisture was seeping through.  With the bathroom, it's only the first layer.  Finally, there is no pattern or localization of the flaking/bubbling.  It has popped up on three of the four walls, as well as part of the ceiling, but in a place on the opposite side of the room from where the original leak was.  So I'm pretty confident that if I deal with the top layer, and properly apply the primer and top coats, it should fix the problem.

But I guess time will be the judge if I'm correct or not.  Based on the previous comments, I'm going to do most of the removal through scraping, and sand only when necessary.  Thanks much for the advice.