Am i going to be able to add a ceiling?

[heiner921]

I have an old pole barn with a quonset hut like wall i'm using as an automotive shop. Over the next summer i plan to insulate the shop and id like to add a ceiling to the bottom of the trusses. the truss span is 6ft on center. my plan as to use osb as a ceiling and then blow insulation on top of that. my issue is that there is probably going to be a good sag being 6ft on center. and the added weight of the insulation wont help. whats the best way to add this ceiling? and will these trusses hold the weight. there is virtually no snow load (snow doesn't stay on the roof) due to the steep angle of the roof pitch and the curve quonset shape.

or plan B Insulate the inside of the roof and then just use plastic 4 mil sheathing stapled to bottom of trusses to keep the heat to a smaller area?

what should i do fellas?

pic of shop in next post

 

[heiner921]

Pics

 

[lakeroadster]

Those look more like rafters than trusses. And are they overlapped at the peak?

Maybe get a picture a bit farther back and a couple outside shots too.

In regard to other environmental loadings, such as wind, what's your location and what is near the building?

 

[strutaeng]

Install 2x4 flatwise perpendicular to trusses at 24" o.c. with Teks screws.

 

[strutaeng]

Oh, they looked like steel bottom chords, but I guess they are wood?

 

[heiner921]

Located in southern WI. The building is pretty out in the open. Closed other building g is the house which is over 50ft away. Rafter/trusses. Tomato/potato. Here are more pics

 

[rburke65]

I don't think the rafters .....I don't see trusses......are suitable for a ceiling of OSB and insulation. Things king you are going to Ned some light weight foam sheeting for a ceiling.

 

[stm317]

I wouldn't trust that design to hold much weight with 6ft centers. OSB will sag over that kind of span, even thick stuff. And that will add a bunch of weight that's not insulating. As suggested, using rigid foam panels with no other insulation might be the most reasonable option since they'd provide insulation and a ceiling at the same time.

 

[Radix2]

Metal is light and won't sag over that distance, screw it up and insulate.

 

[lakeroadster]

As suggested, using rigid foam panels with no other insulation might be the most reasonable option since they'd provide insulation and a ceiling at the same time.

Nearly every type of foam panel specifies that it be be covered.

heiner921,

What is the span of the lower chord, from the concrete wall support all the way over to the roofing steel on the opposite side?

Armed with that data you can select the proper joist size and material that you would add to your building to support your proposed ceiling.

http://www.southernpine.com/app/uploads/SPtable15_060113.pdf

 

[heiner921]

What is the span of the lower chord, from the concrete wall support all the way over to the roofing steel on the opposite sid

I'll have to double check but sould be 25ft

 

[stm317]

Nearly every type of foam panel specifies that it be be covered.]

So buy foil or fiberglass faced foam panels? Or cover it with vapor barrier? Or coroplast sheets? I agree that none of these is better than properly framing the garage and installing an actual ceiling, but there are options.

 

[73fxe]

Install a drop ceiling and use 1 1/2" foam for ceiling tiles.

 

[rburke65]

OH....that's a great idea! Light weight and structural.

 

[heiner921]

U guys are all confusing me....

 

[heiner921]

Here is what I think I'm going to do... Frame between the rafters on bottom chord with 2x4 or 2x6 2ft O.C. then I'll use 1" foiled faced styrofoam insulation board hanging from the new studded ceiling.
Johns Manville Foil Faced Polyiso Foam Insulation 1" x 4' x 8' R-6 at Menards https://www.menards.com/main/p-1444438920507.htm

Only thing I don't like is the low R-value of the insulation and my local menards only carries up to 1". 2" is special order, twice the price, and have to add special shipping too....

... Think that would do the job? Or too heavy for the rafters?

 

[CraigStu]

I have seen foam sheet that was 2 inches thick. Maybe that would be rigid enough to skip the 2x4s so you don't add weight. But isn't foam going to need some type of fire rated covering?

 

[heiner921]

There is a guy selling 30 4x8 sheets of 2" thick for 300 but it's sitting out in the snow... Safe to say that's junk now?

https://milwaukee.craigslist.org/mat/d/30-4x8x2inch-thick-insulation/6445290658.html

 

[shedfullatools]

There is a guy selling 30 4x8 sheets of 2" thick for 300 but it's sitting out in the snow... Safe to say that's junk now?

https://milwaukee.craigslist.org/mat/d/30-4x8x2inch-thick-insulation/6445290658.html

The weather wont bother it much as long as it didn't see too much sun, one of our local hardware stores kept the white foam sheets outside for ages and people still bought. Those ones don't look like they are very clean though, doesn't take much to make the white foam look filthy.

 

[matt_i]

That building being asymmetrical is an oddity. In my opinion it presents some diffficulties in transferring the load downward on the metal side of the building as there isn't a clear vertical load path.

What's your intended use and heat source? Warm it up for a few hours here or there, or is it something where you work in there quite a bit?

I would let that choice guide my project, the more amount of time it will be heated, the more I'd pay attention to insulation thickness. I think the R-30 attic is not a bad choice but obviously that's going to require more framing.

R6 could work but its not much of an air barrier with butted 4'x8' panels, so you'd either have to put plastic sheeting up beforehand and tape it, or tape all of the flat seams after the fact. Imo you will need some kind of very large fender washer or cut up squares of plywood to be a large washer for whatever kind of screw is used.

You can cost both projects out, the loose fill cellulose is pretty inexpensive compared to the foamboard, but the framing is of course the additional amount.

 

[lakeroadster]

Here is what I think I'm going to do... Frame between the rafters on bottom chord with 2x4 or 2x6 2ft O.C.

... Think that would do the job? Or too heavy for the rafters?

That will be too heavy for the existing ceiling joists. To do this correctly you will need additional ceiling joists.

I'll have to double check but sould be 25ft

U guys are all confusing me....

Again, how wide is the span?

 

[heiner921]

Would like to keep it 40 degrees minimal in the winter. Currently going through a week of -teens weather. I use the shop for automotive repair and all of my tools are freezing along with lubricants are froze. I pIan to use a LP heater (big Maxx) as I already have a 750 gal LP tank for the house.

 

[heiner921]

I'll get measurements when I get home today. Been gone on vacation.

 

[stm317]

You haven't mentioned a specific budget, but the irregular building shape and the lack of support structure for normal insulation makes spray foam on the underside of the roof seem pretty appealing.

 

[850xpeps]

I think spray foam is the option I would be pursuing. It’s gonna cost but it eliminates trying to properly span that wide as you will need end support for the joists as well. Those are rafters....not trusses it’s not a tomato potato thing. Also if those rafters overlap it’s not the best. They should **** in. But usually metal quanzet don’t need extra support anyway. Yours is just a bit butchered.


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[lakeroadster]

Nearly every type of foam panel specifies that it be be covered.

So buy foil or fiberglass faced foam panels? Or cover it with vapor barrier? Or coroplast sheets? I agree that none of these is better than properly framing the garage and installing an actual ceiling, but there are options.

The options you speak of all add weight to a ceiling that needs proper support.

The foam needs an Ignition / thermal barrier.. and a foil faced sheet or a vapor barrier isn't adequate for that purpose.

Or, as the manufacturer of the foil faced sheet states: "Foil-Faced insulation must be covered with an approved thermal barrier and cannot be left exposed."

https://www.jm.com/content/dam/jm/g...al_Installation_Instructions_Crawl_Spaces.pdf

 

[heiner921]

22ft to be exact is the span

 

[lakeroadster]

22ft to be exact is the span

So you if your local lumber yard can get you MSR (2400f - 2.0E) 2x8's that are 22 feet long you could space those at 24" o.c.. These will act as the new ceiling joists.

Or you could use 2x10's made from No. 1 grade material.

If those aren't available (likely they aren't) you could use I-Joists of equivalent capacity instead of the 2x8's. That's probably what will be needed.

I would not use the existing ceiling joists that are spliced, nor would I sister new ceiling joists to what is already there. Just add new and leave the existing materials alone.

You will need to created a header that spans between the existing 6' span wooden building supports on the end opposite the block wall. This header will support the new ceiling joists. It would be prudent to sister vertical 2x8's adjacent to the current building supports straight down to the slab. This takes the ceiling load off the building supports. You could also use the sistered 2x8's as the framing to insulate the side wall also.

Once done the ceiling will be able to handle a live load of 10psf and a dead load of 5psf. And you're not relying on the existing steel and wooden structure for support.

 

[heiner921]

Am I better off just spray foaming to whole thing and not worrying about a ceiling all?

 

[lakeroadster]

Am I better off just spray foaming to whole thing and not worrying about a ceiling all?

You now have the information to get some quotes and determine that.

With spray foam and no ceiling you will be heating about twice as much space... and the heat rises up into the half of that space which is of little use to you.

Do you have any roof leaks? The spray foam will trap the moisture and lead to quicker rust issues.

Sadly there really aren't any slam dunk obvious answers... ya just have to figure out what is best for you.

 

[bczygan]

Am I better off just spray foaming to whole thing and not worrying about a ceiling all?

Yes.

You can also spray foam the outside and solve the potential roof leaks.

I would go suspended ceiling with blow-in insulation.

Bill