Bathroom wall issues

[kursplat]

SHORT STORY: house built in 49'. it's lath and plaster. using drywall to cover hole made to inspect plumbing. do i use mortar to do a wet line at the bottom? or can i put a 2x4 in there to use for a nailer? old stuff looks like mortar. also, behind the tile, where the wall lays up against the edge, i'll need to back fill a bit. use mortar there too or is there something else that would work better for both?


LONG STORY: so i got home from work the other night and found water all over the bathroom floor. traced it to the trap under the sink, had a pin hole in the bottom. we've had a pedestal sink that was here when we bought the house, and i've always hated it, PITA to get to the plumbing, so i decided that's going away and got a small vanity. the galvanized drain line going into the wall had some scaly rust crud in it and i wanted to make sure the T (cast iron) and drain line in the wall were ok, so i opened it up to take a look. looks good. the **** in the pipe cleaned up fine and the pipe's solid. now i need to close the patient.
thanks

 

[Kaizen]

Use whatever wood isthe right thickness to fir out all edges so the new drywall is level with plaster. Use joint compound aka drywall mud. The old stuff is plaster. Yes hard as a rock. Very hard to apply well so stick with drywall.


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[egdede]

Don't use pre-mixed joint compound. Use hot-mud. The kind of joint compound you mix with water yourself. It is a plaster based product that is far superior to boxed joint compounds.

 

[The Tinkering Juggernaut]

Don't use pre-mixed joint compound. Use hot-mud. The kind of joint compound you mix with water yourself. It is a plaster based product that is far superior to boxed joint compounds.

I've never used anything but the premixed stuff. What make the hot-mud better? Just curious so I will know next time I have to do a repair.

 

[Kaizen]

I've never used anything but the premixed stuff. What make the hot-mud better? Just curious so I will know next time I have to do a repair.

Nor have I found the need. If you don’t do it every day is it worth risking mixing it up too thin or thick?
Op has a little area that won’t even need a small bucket of mud. No brainer


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[dogdog]

I've never used anything but the premixed stuff. What make the hot-mud better? Just curious so I will know next time I have to do a repair.

I have only used premix stuff mostly too... not sure either... only case where I think I wanted to use those plaster of paris (hot mud) is when I want it to dry quick on a quick job... premix stuff takes a longer time to dry... which is not an issue if I have a lot of joint to finish... and usually a patch takes 3 layers so... 3 days. not a problem.

 

[u2slow]

I use a product called "concrete fill". You can roughly plug the hole with drywall and this stuff will take care of the rest. High build stuff - can prob do it in one shot.

https://www.usg.com/content/usgcom/...-finishing-compounds/synko-concrete-fill.html

 

[ThomasZ]

I have a kind of the same issue but not concerning bathrooms. My garage is underground and above there is a CAR WASH. And have no idea how to handle that humidity. I can see the bricks near the ceiling changed their color, and the water from that car wash is leaking through. Do you have any ideas? I thought I could place some heaters or dehumidifiers like these Keystones in there, but that's gonna cost me a fortune

 

[kursplat]

thanks everyone, been doing some more reading and am leaning toward green board right to the floor, taping the joints and hot-mud. i'm going to have other areas to patch anyway in other parts of the house. a couple where the skin coat has completely de-laminated from the drywall, so i might as well learn. think i'll also use mortar to fill in behind the tile. ThomasZ, that sounds like a terrible place for a garage. shouldn't the car wash be responsible for sealing their floor? i would think all that water keeping it soaked like that wouyld become a structural issue. maybe call building and safety

 

[kursplat]

well i'm about half way through this and the hot mud is definitely the way to go. got a bag of 90 minute setting to start with and it's so much better than pre mixed

thanks

 

[Git]

I've never used anything but the premixed stuff. What make the hot-mud better? Just curious so I will know next time I have to do a repair.

Hot mud is like concrete - a chemical reaction causes it to harden and it usually doesn't shrink. You can buy it in different work times - 20 minute, 45 minutes, 90 minutes, etc. Note, this is the time it takes to harden, but it usually takes longer to actually dry. (There is usually a color change from grey to white). If you want it to set up faster, use hot water. Once it is dried, its dried - you can't do anything with it


Regular joint compound - dries by evaporation

 

[The Cobbler]

I use tons of 20 & 90 . it's great stuff/ we do a lot of patching & what would take days with premix can be done within a day , except for maybe sanding . and as mentioned, it doesn't shrink & it doesn't have to be dry to go over. (it's cured hard but not dry)
Our jobs are time sensitive, we need to get in & get out ASAP in most cases

 

[kursplat]

so the hot mud worked out great. my skills at laying it on the walls **** but i was getting a little better at the end. it actually sanded pretty well too. i also picked up one of these drywall sanders with a vacuum attachment. it ended up being a bit of a pain so i used the sanding screens that came with it on my old sanding block and let the dust fall to the floor. worked awesome, just took a lot of time.

 

[htmdude57]

I too am an amateur- always used HD bucket mud. My house has hard plaster. But I have some repaired spots where I patched in sheet rock, using 2" paper tape around the edges, bridging from the sheet rock to the hard plaster. In a lot of those places, the paper tape has pulled away from the hard plaster. Does the hot plaster mix hold on tighter to the hard plaster? I have also thought about using a 4-6" fiberglas mesh tape instead of the 2" paper tape. Would that hold tighter to the hard plaster?