Roof structural problem

[Cougar]

Have a 30 x 50 pole building.
Had planned to finish the inside.
Planned to use liner panels on the ceiling and walls.

Wasn't sure about framing on the ceiling for the liner panels.

So I emailed the manufacturer of the building.
Get a reply to call them.
Call and talked to a guy, he get's out my plans from when they built the thing about 10 years ago.
Tells me my roof was built only for snow load, so it won't support a finished ceiling.
I didn't know enough about it when we built it. I'm sure I told them what my plans for the inside were.
He is going to do some calculating to see if maybe I can finish the ceiling, but it doesn't look like it.

What could I do to beef up the trusses.
It's a 30ft span 4/12 pitch, standard truss.

 

[NUTTSGT]

If they tell you they are only built for snow load then you might want to listen to them.


OTOH, I wonder how many building are out there with ceilings put in them and were only made for "snow load" ? If it was mine, it would have a ceiling inside it.

 

[JordonMusser]

Couger,
I structural engineer will be able to to tell you what to beef up to get your ceiling in....

 

[MScott]

What about using aluminum roofing material for the ceiling. Should be a lot lighter than drywall or OSB. I have seen several on here use it.

 

[Cougar]

If they tell you they are only built for snow load then you might want to listen to them.


OTOH, I wonder how many building are out there with ceilings put in them and were only made for "snow load" ? If it was mine, it would have a ceiling inside it.

I'll bet there are a few out there.

Couger,
I structural engineer will be able to to tell you what to beef up to get your ceiling in....

He's getting back to me, we'll see what their engineers have to say.
I asked him about sistering a 2 x 6 to the top chord on each truss, he said that would just be dead weight

What about using aluminum roofing material for the ceiling. Should be a lot lighter than drywall or OSB. I have seen several on here use it.

That's an idea. I have seen a few pics of it done that way, it looked good.

 

[jwith68]

Most trusses that are built for a finished ceiling allow 5 lb/sqft for that finished ceiling. Liner panel won't weigh anywhere near that - less than 1 lb/sqft, barely over that with fiberglass insulation over the top. So on a 30' truss (assuming 2' spacing) that's only an additional ~60 lbs total. Not enough to make me worry much about it.

 

[woodrail]

Just about every structural engineer I've worked with computes in a significant safety factor. Hell, some compute one then double it. It's the old "I can sleep at night" theory.

 

[nehog]

If you have not read this: read it. Then ask the maker for the load specifications for your building. Once you have these you may have enough information to determine how much weight you can hang up there. There are many light-weight ceiling solutions, though sometimes you have to 'think out of the box' to find one that will work with your constraints.

 

[Cougar]

Most trusses that are built for a finished ceiling allow 5 lb/sqft for that finished ceiling. Liner panel won't weigh anywhere near that - less than 1 lb/sqft, barely over that with fiberglass insulation over the top. So on a 30' truss (assuming 2' spacing) that's only an additional ~60 lbs total. Not enough to make me worry much about it.

The posts and trusses are spaced @ 10ft.

 

[kbs2244]

The lightest interior ceiling I know of is the 2x4 “dropped ceiling” panels you see in stores and basements everywhere.

Check it out.
It is cheap, light, and the panels come in dozens of patterns.
(And give you access to the above area if you ever need it.)

Putting up the support grid is a little tricky in keeping it level across long spans.
(They use laser levels.)
You might want to check out having it done.

 

[Playwme]

What about the polycarbonate panel systems? They're pretty lightweight. Bit more expensive than OSB or drywall but they're easy to install and most don't need painting or anything.

 

[Cougar]

The lightest interior ceiling I know of is the 2x4 “dropped ceiling” panels you see in stores and basements everywhere.

Check it out.
It is cheap, light, and the panels come in dozens of patterns.
(And give you access to the above area if you ever need it.)

Putting up the support grid is a little tricky in keeping it level across long spans.
(They use laser levels.)
You might want to check out having it done.

I put up a few drop ceilings, they turned out good.
I have thought of doing that. Wonder if it would look kinda weird in a pole building.

What about the polycarbonate panel systems? They're pretty lightweight. Bit more expensive than OSB or drywall but they're easy to install and most don't need painting or anything.

Pretty sure I priced those, iirc they were expensive.

 

[bczygan]

The problem with pole barns that are NOT designed for extra loads is that they usually have, like you, trusses spaced far apart. The weight of a ceiling, and more importantly, the additional framing needed to support the ceiling, add a lot of weight.

A lightweight ceiling is one option. Another is to add trusses in between the existing ones, to cut the distances between them, and add load support capability.

 

[jwith68]

The posts and trusses are spaced @ 10ft.

That's a much different situation than 2' or even 4'.

The problem with pole barns that are NOT designed for extra loads is that they usually have, like you, trusses spaced far apart. The weight of a ceiling, and more importantly, the additional framing needed to support the ceiling, add a lot of weight.

A lightweight ceiling is one option. Another is to add trusses in between the existing ones, to cut the distances between them, and add load support capability.

Agree, the weight of the extra framing starts to be a significant issue.

 

[Zeke]

The problem with pole barns that are NOT designed for extra loads is that they usually have, like you, trusses spaced far apart. The weight of a ceiling, and more importantly, the additional framing needed to support the ceiling, add a lot of weight.

A lightweight ceiling is one option. Another is to add trusses in between the existing ones, to cut the distances between them, and add load support capability.

That's a much different situation than 2' or even 4'.



Agree, the weight of the extra framing starts to be a significant issue.

The upper girts might not be designed to carry additional trusses. But you could beef them up and then install only what is needed to carry the new ceiling.

With regard to a suspended ceiling, there are many ways to tie them off to the upper structural members and there are many ways to fill in the grid once installed. One is to place 2 x 4 foam sheets 2-3" thick in the grid as the finish ceiling. You will be getting a solid insulated ceiling with all in one shot. Super light weight, too. They can be painted before installation.

Look for suspended ceiling grids at salvage yards. I bet you can do this for a fraction of what some would have you spend.

 

[joe_padavano]

Just about every structural engineer I've worked with computes in a significant safety factor. Hell, some compute one then double it. It's the old "I can sleep at night" theory.

WOW. Written by a non-engineer, apparently.

The safety factor is for unknowns or unquantifiable items, like knots and cracks in the lumber, incorrectly-spaced nails, and non-uniformity in loading. Do you do 100% ultrasound or xray inspection of your framing lumber to guarantee it has completely uniform structural properties? Do you exactly measure the spacing of nails? Can you guarantee that there won't be snow drifts on the roof?

 

[Ray Kelly]

Uhhhhhh....huh? Did he say it was built for a snow load but not for a ceiling? What's the difference? I remember when I first had my metal building but in and we had a snow that piled up about a foot on the roof. I was afraid it would fall in. I called the guy who sold it and he said it was made to hold three feet of snow. So, I can't see why it won't hold some type of ceiling if it isn't too heavy.

 

[nehog]

Uhhhhhh....huh? Did he say it was built for a snow load but not for a ceiling? What's the difference? I remember when I first had my metal building but in and we had a snow that piled up about a foot on the roof. I was afraid it would fall in. I called the guy who sold it and he said it was made to hold three feet of snow. So, I can't see why it won't hold some type of ceiling if it isn't too heavy.

Yep, until it snows the big storm, then all bets are off!!! Or are you proposing he remove the ceiling during the winter?

 

[woodrail]

WOW. Written by a non-engineer, apparently.

The safety factor is for unknowns or unquantifiable items, like knots and cracks in the lumber, incorrectly-spaced nails, and non-uniformity in loading. Do you do 100% ultrasound or xray inspection of your framing lumber to guarantee it has completely uniform structural properties? Do you exactly measure the spacing of nails? Can you guarantee that there won't be snow drifts on the roof?

WOW. Obviously you are the expert on the subject!

I stated my experience, that's all. Do you suppose the truss manufacturer added in a safety factor also? How about the lumber mill? Maybe the plate manufacturer?

Thanks fr the slam. Have a nice day.

 

[JakeKohl]

WOW. Written by a non-engineer, apparently.

The safety factor is for unknowns or unquantifiable items, like knots and cracks in the lumber, incorrectly-spaced nails, and non-uniformity in loading. Do you do 100% ultrasound or xray inspection of your framing lumber to guarantee it has completely uniform structural properties? Do you exactly measure the spacing of nails? Can you guarantee that there won't be snow drifts on the roof?

True, safety factor is in place to help prevent failure from a combination of variables - but it's use is still relatively conservative. I'm an engineer and we constantly design steel structures with safety factors well above the possible combined variables...and it is a safety and comfort knowing that you are well within a defined limit.

It sounds like the OP needs to build a building within the existing building. Build walls and a ceiling structure that will support the loads you need and move on.

 

[Cougar]

Yep, until it snows the big storm, then all bets are off!!! Or are you proposing he remove the ceiling during the winter?

Yeah I was thinking soon as I put up a ceiling we will have record snowfall.
And the roof will cave in.
I could do like we did at the deer hunting cabin. In the winter when we left we would put a post up under the beam in the center of the ceiling in case there was a lot of snow.

True, safety factor is in place to help prevent failure from a combination of variables - but it's use is still relatively conservative. I'm an engineer and we constantly design steel structures with safety factors well above the possible combined variables...and it is a safety and comfort knowing that you are well within a defined limit.

It sounds like the OP needs to build a building within the existing building. Build walls and a ceiling structure that will support the loads you need and move on.

This is going to be a lot of screwing around to finish a ceiling.

 

[Cougar]

Had them come out and take a look at it.
Told them to shoot me a price on them beefing up the structure and finishing the ceiling and walls with liner panel.
They planned to add a couple trusses to hold the ceiling weight.
Was a lot higher than I thought it would be. More than I want to spend.

If I want it finished will have to do it myself.
Have another idea.
What if I construct beams to place in between the trusses to hold the ceiling.
First have to calculate the weight of the material for the ceiling.

Any thoughts?

 

[ozyborn]

One of my good friends just used 4x8 sheets of Styrofoam panels 6 inches thick. Couple screws in each then paint. Very little weight and help heat the shop. Your mileage may vary.

 

[Norcal]

One of my good friends just used 4x8 sheets of Styrofoam panels 6 inches thick. Couple screws in each then paint. Very little weight and help heat the shop. Your mileage may vary.

Styrofoam: Gasoline in a solid form,if that **** catches fire heaven help the poor souls inside.

 

[nehog]

Styrofoam: Gasoline in a solid form,if that **** catches fire heaven help the poor souls inside.

Yep, just remember the Station fire in RI, as an example of what can happen.

My plan is to use rigid foam and cover it with white 'air-frame' fabric. Since the air-frame fabric is designed for making structures, that seems relatively safe considering all other alternatives. It will not be (by any stretch of the imagination) fire resistant, but the only compromises for my building (which like the OP's is not designed for a heavy ceiling) are not really feasible either.