Yesterday my daughter called for help finding a leak that was damaging a wall in her kitchen. After punching a couple holes in her spongy wall we found the leak in the upstairs bathroom that was dripping down the wall cavity (balloon-framed 1924 home). The damage is limited to one stud bay floor-to-ceiling behind the stove.

Will plaster dry out so only spot repairs will be needed or will the entire wall need to be skinned of plaster & wood lath & re-sheeted with drywall?

 

The fact you described the wall as spongy makes me think drying it out will not suffice and more work will be needed.

 

The odds are any drywall that is spongy will need to be replaced. I'd go ahead and remove that drywall so the stud cavity can dry out quicker.

 

Not drywall--it's plaster. I'm not familiar with plaster & don't know if it will dry out OK.

 

I'd still be inclined to tear it out, I don't know a lot about plaster but the wall cavity still needs to get good and dry. What type of lath do you have?

 

A house this age probably has wood lath. That lath was as dry as a dead bone for ninety years. when the lath got wet they swelled and buckled and twisted and broke the keys that held the plaster to the lath. If the plaster does not come loose now it will in time. You can take the plaster off and leave the lath and replaster it as good as new. It can be done by an amateur if you let us @talk you through it. Or you can use drywall but the thickness won't match. The advantage of plaster is it always fits.

 

I would dry it out with some air movement and allow it to set for a few weeks. If it doesn't show signs of cracking or scaling on the surface I would probably just patch in the holes you made and let it be.

Depending on the size of the holes I would use either durabond joint compound or gypsolite base coat plaster if you have large holes. You can skim the gypsolite with durabond or regular joint compound for a finish coat.

I have worked in houses with wood lath and plaster walls that went through several days of flooding. It is interesting to note that many of those walls were still serviceable after the flooding. In most cases we took off the baseboard and plaster and lath (behind the baseboard only) and introduced forced air flow up the wall cavity to assist drying. The faster that happens the better off you will be regarding damage and mold issues.

Remember that plaster of that vintage is primarily composed of gypsum and sand. The sand is not absorbing water, the gypsum will but not enough from the situation you had to do great damage IMO.

The greater damage may occur on the finish coat when water reacts with the lime in the finish to produce a situation that will attack the oils in your original paint to produce a situation that necessitates removal of the finish coat.

I vote to give it a chance unless you can come up with a reason to rip up the place to do something like insulate or upgrade utilities in the wall.

 

Might have to be a combo approach. They're budgeted pretty tight on this first home and I'm pretty sure insurance will deny the claim. The leak that caused the water damage needs to be repaired and that may necessitate skinning one side of the wall and the ceiling under the bath to run new (not steel) pipe. They can still use the kitchen with the ceiling out but I'd like to save the kitchen-side of the wall or they will be without a stove & microwave til repairs are done.

 

I modify my assessment and advice a bit. Since this is behind the stove and maybe there are cabinets above the stove this wall is not subject to a lot of contact. The plaster is probably loose from the lath but will stay until disturbed. Do the cosmetic repair and wait until the remodel, which is sure to happen eventually, then take off the plaster that is loose. Decide then how to deal with the repair.
UNLESS this is an outside wall and there is wet insulation then best take it off, dry it out and repair it. We can tell you how to do this with plaster (or drywall if you insist.)