I own a home that was built in the mid 70's. It has in-ceiling radiant electric heat that is constructed by putting one layer of 5/8" sheetrock on the ceiling, stapling 240v wiring all over the sheetrock, and then covering that wiring with a plaster-like compound that creates a textured ceiling look. I know how this is put together because I had all the sheetrock on my ceiling in my downstairs family room fall down a few years back. Luckily nobody was down there when it happened. I'm assuming that the sagging section I saw finally came down and all the wiring helped pull all the other sheets down. It was a mess. I'm not sure why it fell. There was no evidence of water damage and they used nails and screws to attach the sheetrock. They were all left in the joists after the sheetrock fell. My problem now is that I have an area in the living room upstairs that is sagging pretty bad. It's an area about the size of two sheets of sheetrock. I know that I need to get into the attic to remove any insulation that has gotten between the sheetrock and the ceiling joists and then prop up the sheetrock. With the wires stapled to the sheetrock, though, I can't just start putting screws in. I need to be able to locate the wires and the ceiling joists from below. I have a nice stud finder that seems to be rendered useless by the plaster type material and the wiring. Does anyone have any ideas how I can locate the wires and joists to be able to fix this on a very limited budget?

 

Electricians might have an instrument that can pinpoint the wires. If they do have one find all the wires for you and snap chalk lines for all of them. don't use red chalk. Prop it up and rescrew. Use long enough screws to go through both layers of drywall plus the gap between.

You are not the first person to have this happen. I wonder if there is some inherent problem with the system.

 

Yeah, I'm sure electricians can pinpoint them. I don't really have the money for that though, unfortunately. I'm trying to figure out some way that I can do it on my own. If I can't figure out any cheaper method, I may have to hire an electrician to do that. By the way, there's only one layer of sheetrock. It's 5/8" sheetrock attached to the joists, then the wires are stapled to that sheetrock and then a plaster type coating is applied to cover the wires and make a textured ceiling. I don't know why I'm having trouble with it. I would have guessed that maybe it would be caused by using only nails but when my ceiliing came down downstairs, I could see that they used screws and nails. Maybe they just weren't very good at installing sheetrock and broke the paper with all the nails and screws. Who knows.

 

I've painted quite a few ceilings that were done that way but the thing that amazes me is that your ceiling heat is still working after 35-40 yrs. I think the majority of them quit working after about 20 yrs.

Could you maybe chip off some of the plaster/texture on the sagging area to figure out where you can install the screws?

 

Until the sheetrock ceiling downstairs fell a few years back, all of my ceiling heat worked great. I hate not being able to put anything in the ceiling like a ceiling fan or light but otherwise I like the heat. I don't think chipping away the plaster coating would work. After the ceiling downstairs fell, I could see the plaster type coating is really thick and brittle. I'm afraid that if I chip away at it, big chunks will fall off. I'll add it to my list of things to try though if others don't work. I wonder if one of those non-contact thermometers would help me "see" where the wires are.

 

Time was radiant electric heat was installed over gypsum lath. The lath was 3/8" thick 16" X 48" and then the wires then gypsum plaster about 1/2" thick. The lath was nailed with blue nails. This heat was clean, quiet and at the time cheap because there were special electric rates for electric heat. I have seen plaster exposed to that kind of heat calcine. It must be possible for gypsum to calcine at fairly low heat given enough time. I suppose it could be that the gypsum core of the drywall also calcined and lost its strength. If so more screws or nails might not hold very well either. Add some washers to get more bearing. Use a spade bit to countersink the washer into the plaster, draw up the ceiling then patch the holes where the washers are.

 

I'm missing something here - is the whole ceiling sagging or just between the joists?

 

An area about the size of two sheets of sheetrock is sagging, not just between joists.

 

So the screws and nails have already pulled through the paper on the sheetrock in all likelihood (based on the fasteners staying in the ceiling after the failure in the other room)?

 

That's what I would assume. I haven't been up in the attic yet to try to look at it from the other side. It's a little ways from my attic access and I just haven't found the motivation to crawl all the way over there.

 

You sure want to get this put back up if possible before it comes down. You know the mess of the insulation falling.

Do you have other heat in the house?

I know from experience that the wires are spaced about every 2" - 3" all across the room. They calculated how much wire it takes to heat the room then the electrician just got that much wire in the lid however it could be done. The chances of hitting a wire are pretty good.

I know you are trying to do this low budget. Can you just screw the lid back up and install radiant baseboard heat? Maybe there is something like an electric radiant crown molding or something of that nature.

Or, if the joists will handle the weight can you install the same system right over what you have. Just use long screws.

 

I don't have any other heat and really don't want to switch to baseboard heaters. That's actually what I did downstairs where the ceiling fell a few years back and the baseboard heaters don't heat nearly as efficient as the ceiling radiant heat. I'm also thinking that the extra weight and expense of installing this system right over the top wouldn't be good. I think everything in this house was framed to meet bare minimum requirements like span ratings or maybe less...lol. My kitchen floor is so unlevel it's ridiculous. That may have contributed to the ceiling down below falling. If the floor joists sag, the sheetrock probably absorbs that stress which could have caused problems. Do you think I could locate the wires with a non-contact thermometer?

 

I found a cheap non-contact thermometer at Harbor Freight's site for $15.00 for that price you could try it and see if there is enough temperature differential between the wires and the field of the room to show the actual location of the wires. There are other n-ct's that have a laser spotter. That might be a good idea if the principle is sound. My experience with those wires is that they don't run in perfect patterns but if the thermometer does in fact work you could try a shot each place you intend to put in a screw and see if it is in the clear.

There has to be someone with experience in this kind of thing. All I ever did was plaster. We did always check continuity before the first coat of plaster and immediately after that coat was straightened, but if we had ever knicked a wire I don't know what the plan was for fixing it.

I think you should try the thermometer and do it when the weather is cold. maybe even open a window so the heat is blown off the surface of the ceiling and you know the wire is heating. I suspect that when there is no current in the wire that it becomes the same temperature as the plaster surface pretty quickly.

Maybe an electrician will let you use his instrument to find the wires. If you do everything you can to find the wires and get the ceiling tightened and then you discover you hit a wire you can deal with that then. Just when you think you know the pattern of the loop you will probably find out there is a change.

Please let us know what you do and how it works. There are other people who want to know what you did even if they do not yet know that they want to know.

 

I have been so concerned about your wires that I haven't dealt with the joists. You can probably use the lines in the sagging panels to figure out where a joist is. Once you find the first one you can find the rest. You can figure out which way they run and the spacing by looking in the attic. When you know about where they are then use whatever you end up using to find the wires and try a screw. If it hits the joist you will know it and if not you will know it. Move left or right a little and try again. If you start rather near a wall and find the joists on each end you can snap chalk lines to mark them in the field. Don't use red chalk.