Understanding ceiling dead load

[Chrysis]

I've been searching all over and I'm trying to understand everything I have been reading. Please correct me if I am wrong about anything I say, terminology, etc. It's been known to happen, frequently.

My shop is 30 x 40 x 10. It has what appears to be 30' 4/12 gabled trusses on 48" centers. The top and bottom chords are 2x6 and the webbing is 2x4. From what I read the load rating should be 25-5-0-5. I've attached a picture of what the trusses look like. I'll add some real pictures as soon as I can, if needed.

That being said, will that support a ceiling? From what I've read, I've seen with sheetroock you need at least 24" on center spacing to limit sagging, but would OSB be too heavy?

Honestly, I just want something on which to blow insulation and reflect some of my light back down. I don't plan on doing any sort of storage above.

Also of note, I'm on an extremely limited budget. =) I can afford to sheetrock it, or OSB...barely.

 

[GMCGarage]

Im guessing here, but I think its 25 top chord live load, 5psf top chord dead load, 0 psf bottom chord live load, and 5 psf bottom chord dead load.

That makes sense, the 25 psf would cover snow, and the 0 psf would be because you are not going to be in the attic living, moving around.

The 5 psf bottom chord would be for ceilings. OSB is about 1.5 psf at 1/2" thick.

You have capacity.

 

[chaosracing]

Its not sag in the joist, but sag in the ceiling materials you will have to deal with. To prevent sag in the ceiling material no matter if its OSB or drywall, you really need a minimum 24" spacing. 4' spacing is for metal ceilings with blown insulation. If you want to go the other route(OSB or drywall), you either need to space joists 24" OC or use strapping.
Just FYI
7/16" OSB = 1.4psf
1/2" drywall - 1.6 psf

 

[sberry]

Steel is for 4 ft spans.

 

[theoldwizard1]

Its not sag in the joist, but sag in the ceiling materials you will have to deal with. To prevent sag in the ceiling material no matter if its OSB or drywall, you really need a minimum 24" spacing.

As an experiment, I would buy a couple of 2x6x16 boards and **** joint them together with 3/4" plywood gussets on each side. Temporarily place it on top of the walls. Carefully measure the deflection at the center. The add some weight to the center and measure again. My GUESS is that the deflection would not be too severe and you could still hang drywall and 12" of blown in fiber glass. Worst case, you might have to go up to 2x8.

Blocking will be require to prevent sagging as stated. That blocking should be installed very tight, to the point that nailing is almost not required.

 

[strutaeng]

I've been searching all over and I'm trying to understand everything I have been reading. Please correct me if I am wrong about anything I say, terminology, etc. It's been known to happen, frequently.

My shop is 30 x 40 x 10. It has what appears to be 30' 4/12 gabled trusses on 48" centers. The top and bottom chords are 2x6 and the webbing is 2x4. From what I read the load rating should be 25-5-0-5. I've attached a picture of what the trusses look like. I'll add some real pictures as soon as I can, if needed.

That being said, will that support a ceiling? From what I've read, I've seen with sheetroock you need at least 24" on center spacing to limit sagging, but would OSB be too heavy?

Honestly, I just want something on which to blow insulation and reflect some of my light back down. I don't plan on doing any sort of storage above.

Also of note, I'm on an extremely limited budget. =) I can afford to sheetrock it, or OSB...barely.

Are these trusses from a manufacturer that quoted you? The way it works is you tell him/her what the construction will be, and he designs for that load. Ask him if the design will support your loads. Asking us to "guess" what his and your numbers are is risky.

As for the 48" o.c. spacing, yeah, gypsum board will not span that far. What you can do is install furring strips at 24" o.c. and attach the gypsum board to that. Again, communicate this with your manufacturer.

 

[GMCGarage]

Are these trusses from a manufacturer that quoted you? The way it works is you tell him/her what the construction will be, and he designs for that load. Ask him if the design will support your loads. Asking us to "guess" what his and your numbers are is risky.

As for the 48" o.c. spacing, yeah, gypsum board will not span that far. What you can do is install furring strips at 24" o.c. and attach the gypsum board to that. Again, communicate this with your manufacturer.

I would be afraid even the furring strips would deflect over long time, at 4' spacing almost need a 2x4.

 

[Radix2]

The metal liner should be cheaper and lighter and is better for spanning...

Why do anything else. Faster too, and no finishing...?

 

[ishiboo]

Steel, without question.

 

[DCarr2]

Just out of curiousity, where are you guys getting the steel cheap? From my limited research it seems to me that steel is the expensive way to go. About double that of OSB/drywall. While its installation is a lot easier because its much lighter, the cost of it seems to be quite a bit higher.

 

[forAK]

Just out of curiousity, where are you guys getting the steel cheap? From my limited research it seems to me that steel is the expensive way to go. About double that of OSB/drywall. While its installation is a lot easier because its much lighter, the cost of it seems to be quite a bit higher.

Metal roofing supplier. Factor in all of the material when looking at drywall. Rock/mud/tape/primer/paint. It adds up, especially if looking at quality primer/paint. Metal is a lot cheaper too if hiring the labor out as it can be done in 1 day. I priced out both with myself installing both and metal was $150 more in just materials.

 

[chaosracing]

Metal roof suppliers. There is a manuf that runs specials all the time. Right now there is a guy on craigslist selling white metal real cheap.
Till you factor in the time it takes to install OSB or drywall, finish seams and paint I will go with metal everytime on the ceiling. Figure to paint OSB or drywall 3 times (primer and 2 coats of paint) just to get same reflectivity as metal. Once the metal is up, your done.

 

[Radix2]

Just out of curiousity, where are you guys getting the steel cheap? From my limited research it seems to me that steel is the expensive way to go. About double that of OSB/drywall. While its installation is a lot easier because its much lighter, the cost of it seems to be quite a bit higher.

Price it out at Menards.com to get an idea.

.63 a square foot right now....

 

[Chrysis]

Thanks, everyone. I'll contact the truss vendor. I went through my paperwork and found who made them.

There is a local guy selling galvanized roofs from dismantled chicken coops for 2 bucks a 3' x 10' sheet. I already bought 30 to use as wainscoting for the walls of the shop. If the truss vendor confirms the 5lb dead weight for the bottom chord, I'll likely get some more steel. It's only a little "Rust"ic, and only 2 bucks a sheet.