Walling off a chimney

We have a plaster-covered chimney in the 3rd floor home office. However, over the decades, it appears that the plaster has developed many warts, bumps, and patches so that it looks more like hilly countryside than a flat wall.
We are considering a couple of options: 1. Trying to scrape off the bumps and repatch (probably though a hopeless task) 2. Taking down all the plaster and replastering 3. Walling off the chimney with drywall (either with or without first stripping the plaster)
- Any thoughts on what is best? - What are the code requirements when either plastering over or drywalling off a chimney? Specifically, how much spacing is needed between the chimney and drywall (particuarly if using fire-resistant drywall)? [Note the chimney is now only used to vent our gas hot water heater which goes up through a metal liner]
Thanks
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You sure have a lot of projects going on. I bet your house is a zoo.
Used only a gas vent with a liner you can do about anything you want and be safe. I can't promise "to code" in your area but it will be okay.
New drywall (green board preferred) attached directly to the existing mess with bugle head Tapcon screws is the least messy easy way to go. Use a liberal amount of drywall adhesive and just the minimum amount of screws.
Option 2 is to furr it out and hang drywall in the normal manner.
Plaster is a really hard DYI project. You could use Durobond as a base coat and regular sandable mud for the top coats.
If there is an open hearth or thimble that your failed to mention, brick it up before adding the drywall.
Colbyt
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We recently purchased the house and there is a lot to get done. I have been trying to prioritize and then do some myself and hire professionals for the hardest, most time consuming stuff. Either way, I try to do my research first online so I can bring in the right people, ask the right questions, and make sure that I am not overlooking important factors or alternatives.

Should I be using the Type X (fire resistant) drywall?

Someone else mentioned possibility of using "hat channel" furring mounted with Tapcon screws followed by Type X drywall as a way of ensuring code compliance (though I will need to check with local building inspector for confirmation).

I probably would hire a plasterer here directly. My most pressing question is really whether it is better to just go hire a plasterer or to hang drywall (which I can either do myself or hire for).

No hearth. Won't know about thimbles if or until I remove the current layers of plaster.
BTW, is bricking out thimbles a DIY job or not? Note, I have never done brickwork but other than the fact that I'm sure it will take me longer and won't look as good (which doesn't matter here), I am not "afraid" of doing it.
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<Edited for brevity>

I don't know your local codes. You should follow them.
A double wall gas vent is rated for 1" clearence to combustilbe surfaces. A properly installed single wall liner would have to heat 3+" of brick to 451 degrees or more to even ignite the paper backing on drywall. I would let my grandchild sleep in this room after the drywall was hung. If X is water resistent, and it makes you feel better, use it. IMO, the water resistent factor is more important in this application than the fire protection because I am betting that the minor moisture that created the bumps will return in the future. Old brick was not "hard fired" and wicks a small amount of moisture forever.

If you can put rectangular objects into a round hole using a LOT of mortar and getting a good seal you can do the job. :)))) And like you said, who the h*&% is ever going to see it.
Colbyt
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I wonder if the top part of the chimney needs to be weather proofed. Your description sounds like moisture penetration. Without some weather proofing, that's going to continue behind whatever you use to cover it.
We have used spakle to fill cracks and gouges in our plaster walls. Depending on adjacent construction and the extent of deterioration, that might be easier than matching gyp board to adjacent surfaces.
TB
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snipped-for-privacy@bellsouth.net writes:

House is old (150 years) so damage has certainly occurred over the years. A new rubber membrane roof was installed about 6 years ago in that area (roof there is flat).
Any good way to tell weather issue has been solved or not?
Is it sufficient to dig into a few sample areas after a big rain storm (or snow melt) and see if any of the plaster layers are noticeably moist?

My only concern with this approach is that it seems like there are already multiple layers of spackle upon spackle leaving the surface so bloated and uneven that stripping it all back and/or covering it with drywall may be the better approach.
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like tbasc said, you may want to wait until you can get the exterior of the chimney watertight before doing anything inside. tuckpoint, sealer, condition of cap, etc. If moisture is working down through the brick and you cover it, it will get nasty and maybe moldy under (and through) the drywall. Bill

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