Got a unique problem here. In a 1950's home, ceiling has radiant heat in it. Ceiling's have cracking threw out house and patching with the usual suspects has not worked. I am looking for the best solution for fixing these cracks. Ceiling is 3 coat plaster over metal lathe.Thanks
Last edited by beetlej; 01-18-2009 at 06:00 PM.
Reason: more info
Yer hosed. The metal lathe will expand and contract with the heating/ cooling cycle. You have to do the whole thing in 3 coat, and do it right, because no drywall product will work. You might price out T+G ceiling. If its electric, I would either remove it or walk away. They have a high fire risk, and if you do something to it, and then there is a fire-
Is the radiant heat hot water or electric? I have never seen electric radiant heat in a metal lath ceiling. Are you sure it is not gypsum lath?
Is the heat still working?
I know a thing or two about heat and plaster. I don't know at what temperature gypsum calcines but I have seen plaster that was calcined behind hot water radiators so I think in time low heat will still cause plaster to soften.
When I was younger I thought electric radiant heat in plaster ceilings over gypsum lath was the greatest thing in the world. Now after fifty years or so I am thinking it isn't.
I think you have a couple viable options:
Abandon the radiant heat and put new rock over the existing lid.
Abandon the radiant heat and install new light weight metal lath over the lid and replaster. The reason I say abandon the radiant is because I don't know how you can either lath or rock without hitting a wire someplace in that ceiling then it is out of order and abandoned anyway.
Keep the radiant heat and embed some fiberglass mesh in new setting compound and then give it another coat or two of setting compound and maybe a topping or all purpose and texture if desired or make it smooth and paint. I haven't tried this but I offer it for consideration. I mean cover the whole lid with mesh not merely cracks.
Another question? Is the plaster soft and chalky?
What part of the country are you in?
Last edited by John McElwee; 01-19-2009 at 04:58 PM.
I think John's idea of the mesh and hard setting compound would be worth the try. We have done this several times and although it has not been over radiant heat, it has yet to re-crack. We mix fine sand into the first coat. Maybe do two coats with sand then a final skim with ready-mix. You can get the mesh at "Mesh-Depot".
Hi Folks thanks for the posts. The house is a two story and is in metro Boston, Ma area. It is hot water radiant heat and it is still in use.They say it provides great heat. The H.O.'s just want to address the cracking, if they wanted to do more I would redo all the ceilings. The plaster is calcining and that is only part of the problem. Plaster is soft and chaulky where the cracks appear. I will take pics and post tomorrow. Thanks Beet
I think it's risky to try to put anything over the plaster if it is soft and chalky. You might try this. It's only a guess but it might work. If the plaster is calcining then replacing the water might cause it to set again. messy but mix up some alum in solution with water enough that you can taste the alum then spray it down until the plaster is pretty well soaked. Maybe, just maybe that will set that soft plaster and then you can do something with it like put mesh embedded in setting compound.