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I’ve heard that greenboard should not be used on the bathroom ceiling, but I don’t know
i why.
Anybody?
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That was a rule invented by a cheap contractor. The entire bathroom can be done in green board. Some contractors only do the shower area and some do it all.
Gabe
*Manufacturer says it is not made for ceiling installation because of it's weakness in holding a fastener. When mounted on the wall, the weight is pushing the sheet toward the floor, not outward toward the room. When mounted on the ceiling, the weight is pushing outward (actually DOWNWARD)toward the room. All of the weight is held by the screw head only. I see it on the ceiling all the time, and it has never fallen as far as I know. Enough screws will hold it, as well as a little adhesive to help secure it. Every manufacturer makes a drywall for ceiling applications. Most areas require fire code, so you gotta use 5/8" type X (fire resistant) on the ceilings anyway. James DuHamel
*Manufacturer okays greenboard for ceilings at 12" oc. If you're worried, just toss up some furring strips to reduce the spacing and screw away. I've not used it but I supose you could run a bead of adhesive, too.Additives to the core that help make it MR reduce some of the rigidity of the board, supposedly increasing the tendency to sag.The only gray board that should be in baths is the gray stuff made out of cement. Everything else should be green. Cement in wet areas, green everywhere else.
*James,Don't forget that the drywall is installed on the ceiling first and then the drywall on the walls are tight to the underside of the edge, making it almost impossible to "fall" down.The weight is a little more but it's probably a regional thing more than anything else.I do it because the bathroom ceiling is exposed to more humidity than the walls, especially over the tub and around the exhaust fan.It's anyones call. (follow manufacturer's recommendations?:))Gabe
*I used greenboard in the entire room of each of my bathrooms and on every bathroom job I have ever done. I use extra screws and space them a bit closer and have never had any problem.I think your risk of having problems with the drywall breaking down due to moisture is higher than the risk of the board coming apart due to its usage on a ceilibng YET I have read the disclaimers from several manufactures that say you shouldn't use it on the ceiling unless the joisttruss spacing is 16" o.c. or closer.Go figure.Mike
*Gabe,Let me rephrase what I was saying. It's hard to concentrate with a toothache (jaw is killing me).USG (makers of Sheetrock brand) say that drywall on the ceiling is a special drywall. It has additives that make it more resistant to sagging. Other than that, I have seen wr drywall on ceilings, and have done it myself a lot. Never had a problem, and have never seen a problem. As you said, the edges of the wall mounted drywall are holding up the ceiling panels at the edge, and giving extra support. I still like to use a little adhesive to help too. Manufacturer also says that wr drywall should not be used around a tub/shower enclosure. This includes the ceiling. The amount of steam/water vapor in this area is greater than the rest of the bathroom. Again, I have seen it used here, and have installed it on the ceiling here myself. Never had a problem.One more thing - code here for major remodels and new construction says that 5/8" type X (fire resistant) must be used on ALL ceilings. This includes bathroom ceilings. Because most of my work is considered repairs, I can get by with using greenboard on ceilings, and 1/2" or 5/8" standard drywall. I am usually matching rest of ceiling, so I get by with it. Here is a link to USG's site for a littel info on wr drywall, and where to use it. I could have found more detailed info, but I got tired of looking. Maybe someone else can look and find the fine details they need. Drywall AnswersJust a thought...James DuHamel
*Thanks for the replies, guys. It seems to make sense to use it on the ceiling, 'cause like Gabe says, that's where the moisture goes. I've only seen 5/8" fire-rated required for attached garages. But there sure are a lot of differences in various parts of the country (continent?).
*James,I'm not familiar with your code requirements for extra fire ratings on the ceiling.Is this right across the board, or for multi levels, multi tenants etc?Is this national or city?Gabe
*As a followup...They now make 1/2" regular drywall that is enhanced structurally for ceiling applications. It says ceiling board right on the panel.I haven't checked with the local drywall supplier but I wonder if the make MR (greenboard) with the same specs for ceilings now?They might as they seem to have about 200 varieties of drywall already!Mike
*Gabe,It is required by the SBBC (Southern Building Code). This is the code I have to go by. My area is pretty spread out, but all the cities in my region go by the SBBC. It is required for ALL buildings, whether single family dwellings, multi-family units, or commercial. I do not know about high rise applications, or situations where electrical/mechanicals are located in the roof/ceiling. All I see in these applications is false drop ceilings. For attached garages, additions, and most commercial work, there must be a solid fire stop between the roofs/walls. I once had to run 5/8" type X drywall all the way up and attach it to the inside of the rafter (just touching the plywood roof decking in the attic area) on a garage I built for a client. It was a gable roof, and tied in directly with the existing roof line. The former exterior wall had a gable vent in it, so the inspector made me run the type X drywall all the way up to cover it and make a closed wall. I could've just as easily framed in the vent, and put some ply over it. He wouldn't let me cause he said code required the firestop. The inspector actually asked me to install some type of bracing on the new drywall to keep the client from cutting an access or vent in it. Sometimes, they get pretty pushy, but this inspector was pretty cool. I did not have to install the bracing. I once took a covered porch, and framed it in for a new room. The ceiling was OSB, primed and painted. Inspector made me take it out and install type X drywall instead. I wasn't allowed to put the drywall over the OSB. It had to come out, and drywall used in its place. Go figure.James DuHamel
*Thanks James,Helps to know the other fellows shoes.Gabe
*National Gypsum makes a 5/8" MR board. The NG rep at my local supplier showed me the documents that state (I'm paraphrasing) that the silicon treatment of the core allows the particles to "slide" around each other and sag. While I accept that answer, and it makes sense, I don't hesitate to use it on ceilings with 16" centers. If I were really concerned about warranty and sagging/falling, most bathrooms aren't so big that it would break the budget to install 2x joists between the 16" center members so that you're sure.Nathan Meredith