1/2" Sheetrock on 24" OC Truss

[hansen1]

I will be installing my ceiling in the next month. The trusses are 19.2" OC. Would I be safe with 1/2" or should I go with 5/8"?

This new stuff is not available in my area.

 

[WVBrady]

One thing to keep in mind is what kind of insulation you are going to put on top of it (if any). Some place, I found a chart that showed how much fiberglass or cellulose (cellulose is heavier) you could put on 1/2" or 5/8" drywall. I have 5/8", with 5 1/2" of fiberglass ontop of it and when all of the lights are off except in the hallway, you can see the shadows caused by the sag. Otherwise, it is not noticeable.

 

[Kevin54]

Houses are built everyday with 1/2" drywall screwed to 24" on center trusses. Just make sure you run the drywall length across the trusses and not with the trusses and stagger the end joints by 4'. If you run it with the truss it will sag between. Guaranteed.

 

[moparman451]

I strapped my ceiling with 1"x3"s perpendicular to the trusses 16" on center, this is common practice and allows for 1/2" drywall without a problem, also gives channels to run wiring in between the strapping, it is against code to run electrical wires over the trusses around here.

 

[southernfriedcj]

I love the house builders that use 1/2 on the ceiling with no problems.

Here's what a real expert has to say at about the 3:40 mark. This is the guy who wrote the book on drywall.

Take it whatever way you want. He is the expert for sure. When I hear you "may" want to do something that means I should do it. It's not worth it for me to have a job that cost hundreds or thousands in labor to accomplish turn out like **** because somebody wanted to save a few dollars on sheetrock. Then it gets torn out and a f'ing diasaster results. So much of homebuilding these days is penny wise and pound foolish. The builders cheap out on the dumbest stuff to save a nickle here and there and deliver a **** product that doesn't rear it's ugly head until years down the road. Most are not anywhere savy enough to know any better. I see it all the time around here and it's sickening. I see houses that builders don't even put plywood on to save a few bucks. Then they stucco over the studs and the shear wall (where the plywood does go) and have a bump out. I see ridiculous stuff all the time. I don't believe I've EVER seen a window or door installed correctly.

Condesending little pissant ain't ya.

 

[hansen1]

One thing to keep in mind is what kind of insulation you are going to put on top of it (if any). Some place, I found a chart that showed how much fiberglass or cellulose (cellulose is heavier) you could put on 1/2" or 5/8" drywall. I have 5/8", with 5 1/2" of fiberglass ontop of it and when all of the lights are off except in the hallway, you can see the shadows caused by the sag. Otherwise, it is not noticeable.

I will be putting R60 worth of blown in cellulose which I think is around 18" deep. The trusses are 2x10 which shouldn't matter one way or another. I will try and find the chart you mentioned to see what 18" of cellulose weighs.

 

[DuluthMN]

I guess I left out some important information. This will be going in a detached garage with 24" OC trusses, 18 to 20" of blown cellulose and it will not be heated all the time. So the garage will easily reach -10 and -20 degrees. I spoke with a local builder in Duluth and he said go with 1/2 osb on the ceiling. He said sheetrock no matter what size will sag if it is not kept heated.

Thanks everyone.

 

[Justanoldguy]

He said sheetrock no matter what size will sag if it is not kept heated.QUOTE]

Yes, but what degree of sag is acceptible.
1/2 will definitely be noticable where as you would be hard pressed to see the sag in 5/8. A no brainer choice I would think.

 

[DuluthMN]

No sag is what I am after. I have decided on 1/2" OSB and I am going to paint it bright ultra white...

 

[Justanoldguy]

No sag is what I am after. I have decided on 1/2" OSB and I am going to paint it bright ultra white...

One sure way to emulate the pacific ocean ..

 

[iowaowb]

This topic caught my eye since I do this for a living. We do residential and commercial work. The things I read through this topic a lot of people had some parts right and some parts wrong. Basically for your application of course always check on your local codes before you do anything. The thing that stuck out in your comments was that you were not going to heat the area full time. That part of the requirements rule out any type of finish beyond a level 1 (other wise it will crack at the joints without special board assembly techniques and material, control joints etc and be a waste of time). Another thing on top of that is to consider that without a controlled atmosphere in the building any time condensation or high moisture you can cause any gypsum board panel to sag, All the manufactures state that you have to have a controlled environment for your common assemblies. A good example is that to do arches or any radius all we have to do is apply moisture to the assembly and once it drys it is there for good. The concern I would have with osb is the combustible characteristics that again depends on what your use of this space will be. I hope that I did not repeat someone else, I did not read every post. Good luck and hope this helps.

 

[jvitez]

This topic caught my eye since I do this for a living. We do residential and commercial work. The things I read through this topic a lot of people had some parts right and some parts wrong. Basically for your application of course always check on your local codes before you do anything. The thing that stuck out in your comments was that you were not going to heat the area full time. That part of the requirements rule out any type of finish beyond a level 1 (other wise it will crack at the joints without special board assembly techniques and material, control joints etc and be a waste of time). Another thing on top of that is to consider that without a controlled atmosphere in the building any time condensation or high moisture you can cause any gypsum board panel to sag, All the manufactures state that you have to have a controlled environment for your common assemblies. A good example is that to do arches or any radius all we have to do is apply moisture to the assembly and once it drys it is there for good. The concern I would have with osb is the combustible characteristics that again depends on what your use of this space will be. I hope that I did not repeat someone else, I did not read every post. Good luck and hope this helps.

Excellent info. Thanks! I'm in the same boat, planning to drywall my attached garage but only heat intermittently. Won't painted OSB look lumpy and decrease the reflectance, thereby reducing the brightness of any paint? And doesn't OSB swell if it absorbs water and then delaminate and/or sag in a horizontal application?

 

[southernfriedcj]

OSB will bow.
I have never seen 1/2" drywall on 24" centers sag. I have put it in 600-700 homes & many unheated garages.
All were in humid Georgia.

 

[nate379]

R60 should be something close to 2ft.

I will be putting R60 worth of blown in cellulose which I think is around 18" deep. The trusses are 2x10 which shouldn't matter one way or another. I will try and find the chart you mentioned to see what 18" of cellulose weighs.