How to drywall a 30'x35' ceiling?

[Leo330]

How to drywall a 30’ x 35’ ceiling?

Perhaps this is not the perfect forum, as technically I’m building a home inside a garage, but I’m building two steel 100x30 buildings. One a garage and one a residence.

I am having a hard time finding joist span tables that address what the LL and DL would be for a non-structural ceiling. No roof loads/snow/ etc.. Just drywall and lights. I want to cover the below area with traditional ceiling drywall. 2x4 walls at each end 9’ height.

So if I turn the joists the short way I need some 30’ lumber. It needs to hold 5/8” drywall, a few lights, and nothing else. I may want to walk across it for repair work, but the space above will be just un-used space, no-storage. Anyone able to give some construction or structural advice on if this is feasible?



Another option I had suggested, by a local hardware store (so I’m not sure they are ideal for structural advise), was to run a LVL (5.5”x16”x30’) across the middle and then use 2x10x18 to span the now split room from the center (horizontal in the above picture). I’m told the purpose of the LVL is to be strong enough to carry all that weight to the ends. Then put some 6x6 under each end. This one LVL is ~$500.

Another idea I had is can I get 30’ i-beams (TJI’s) and span it (vertical in the above picture). Here the tables I find talk about snow load and this will have none of that since it is inside a metal building.

Help? Further questions?

 

[Jking24]

That's a long span to free span with no support. Can you run any cableing from the main structure to help split up the span. Maybe some extremely low pitch trusses are in order. Might be cheaper than the lvl and 2x10's

 

[manwithtools]

TJI's are perfect for this. Call a local full service lumber yard and describe your use case, they will be able to tell you what to use. Might want to consider insulation in the spaces between them - noise reduction from rest of the building if nothing else - speaking from experience in our new office building.

 

[Stuart in MN]

If the building is still under construction, the company supplying the trusses should be able to advise you.

 

[Leo330]

Thanks for the input. I'm not really sure on hanging from the ceiling. I'm a really good mechanic but not a construction engineer. I'm trying to build on a small budget, but also want to feel I have a safe understanding that what I build will do the job. Since it is a steel building there are not trusses per say. I-beams.

I'm very hopefully TJIs will be the correct answer. I'll do some calling on those Monday.

 

[Leo330]

I got some structural input on possible solutions.

1) TJI560's - 3.5"x16"x30' spaced 16" OC. These cost $77.57 ea or about $2,000

2) LVL to split the span and then attached 2x10's. The LVL would be 5.5"x16"x30'. Then 2x10x20' (cut down to 17.5' +/-). The LVL is $498.42 and then 47-2x10's are 289.00 for a total cost of 788.22

I do not fully understand how the LVL can take that kind of load, but I'm told that is what it is designed for. And to put 6x6 under each end to support it. You can see the LVL method is much more cost effective.

Any other thoughts/ input on these two solutions?

 

[manwithtools]

I got some structural input on possible solutions.

1) TJI560's - 3.5"x16"x30' spaced 16" OC. These cost $77.57 ea or about $2,000

2) LVL to split the span and then attached 2x10's. The LVL would be 5.5"x16"x30'. Then 2x10x20' (cut down to 17.5' +/-). The LVL is $498.42 and then 47-2x10's are 289.00 for a total cost of 788.22

I do not fully understand how the LVL can take that kind of load, but I'm told that is what it is designed for. And to put 6x6 under each end to support it. You can see the LVL method is much more cost effective.

Any other thoughts/ input on these two solutions?

I don't think the sizing on the TJI's is correct, if all you are doing is hanging drywall, they are way over size. Also, you don't need them on 16"centers, 24" would work. Going 24" centers saves 9 TJI's and I bet you only need a 12" or 14" tops TJI. The 16" on 16" centers would give you floor loading ratings.

I'd look for ways to make the TJI work, clear span, no center beam hanging down. If you want a clear span using the LVL, don't forget all the joist hangers - and their cost and nailing pain.

 

[manwithtools]

I just went and looked up the Ceiling Joist Span Table for Truss Joists @ 20 PSF (Live) and 10 PSF (Dead) load you would need 11 7/8" 560 TJI 's on 19.2" centers.

Total qty required = 20. Have your supplier price the above TJI and see how that compares.

Link to span table for Ceiling Joist Supporting Attic Load:
https://www.weyerhaeuser.com/woodproducts/document-library/document_library_detail/tb-824/

This table is for TJI® joists supporting “uninhabitable attics with limited storage” as defined in 2018 and 2015 IRC Table R301.5

With 19.2" centers, your drywall would lay perpendicular to the joists with breaks on ever 5th joist (for 96" drywall).

 

[matt_i]

I'm partial to the LVL....but there are two things that take great care. First is cutting it to length, no going back, so measure a few times. The second is raising it safely to height where it can be supported and then the columns braced.

The joist hangers are a thing but Simpson makes a set of specialized screws tailor-made for their joist hangers that can go in with an impact driver that are much easier than ramming a bunch of nails into a rock-hard LVL.

I like the 2x10 because you will have a deep cavity to fill with loose fill cellulose if you decide to roll that way.

The trickiest part of the whole thing with an already-built building is figuring out a plan to thread, angle, and finally move to square/parallel/level the various pieces of the puzzle. Without the clear sky above and 24" gaps between trusses, there can be some head scratching moments. It can go smoothly down to the last 1 or 2 joists to fill because the space to move around has shrunk down.

Its also very important to brace the columns. The post, on-end, is inherently unstable. It needs diagonal, cross-bracing, gussetting, moment-bearing brackets, and so forth to be able to carry the vertical load plus any misaligned or side-loading.

 

[manwithtools]

Unless I'm misinterpreting things badly, you are essentially wanting to build a 30' x 35' room inside of a metal building that is 30' x 100'.

I'm assuming your joists will simply rest on a stud wall as your sketch shows (and that you will have plenty of room to install the joists over the top of your stud walls). With that being the case then the TJI's are the better solution - room for more insulation vs the 2 x 10's, far less labor, no posts to secure or joist hangers to fuss with, no LVL to strugle to lift into place - you will need mechanical assistance for a 30' LVL. Add up the cost of the Simpson hangers and screws and I'll bet you decide TJI based on that alone.

Until folks have built with the TJI's, they can't understand how nice they are to work with. One 30' TJI will weigh 120 lbs., two guys can handle it easily. The LVL will be over 700 lbs., ouch!

 

[Leo330]

I just went and looked up the Ceiling Joist Span Table for Truss Joists @ 20 PSF (Live) and 10 PSF (Dead) load you would need 11 7/8" 560 TJI 's on 19.2" centers.

Total qty required = 20. Have your supplier price the above TJI and see how that compares.

Thank you!

I felt like the person I called to get the joist size was too quick in his response, but I was having trouble finding a table that would give dimensions with attic load only.

I plan for this only to supports dry wall. I calculated 5/8" drywall would be a load of about 2.3psf, so even at that the attic load should be plenty generous. The entire building is 'sealed'. With a ERV and mini-splits, installed on the walls so there are no traditional attic loads. But I do like the 20PSF live b/c on occasion I may need to work up there. Two sheets of plywood and move across the attic, very rare need I hope/expect.

 

[Leo330]

Its also very important to brace the columns. The post, on-end, is inherently unstable. It needs diagonal, cross-bracing, gussetting, moment-bearing brackets, and so forth to be able to carry the vertical load plus any misaligned or side-loading.

In the above do you mean the 6x6 posts running verticel need cross-bracing, gussetting, moment-bearing brackets, etc? I'm having trouble picturing this, do you have a picture of what you are talking about?

I appreciate the input on the LVLs and the counter point to TJIs.

What I'm thinking right now is both methods will safely do the job. I'm feeling like with the LVL method I will have to outsource it's setting. While with the TJIs I can DIY.

 

[matt_i]

In the above do you mean the 6x6 posts running verticel need cross-bracing, gussetting, moment-bearing brackets, etc? I'm having trouble picturing this, do you have a picture of what you are talking about?

I appreciate the input on the LVLs and the counter point to TJIs.

What I'm thinking right now is both methods will safely do the job. I'm feeling like with the LVL method I will have to outsource it's setting. While with the TJIs I can DIY.

The columns that hold up the LVL are holding a lot of load up high. They need some extra lateral reinforcement so they don't tip over. One could bury the post end in a concrete footing, one could cast knife plates into a concrete footing and bolt to the post, one could integrate it into an existing stud wall and then X-brace the wall with flat metal strapping. The upper end of the post connecting to LVL also deserves consideration too. Flat metal plates, Y-shaped gussets/braces could be used.