Pole barn with apartment, ceiling question

[mrpizza]

I am about to start a 40x64 barn that will be 10' 4" to the bottom of the truss. A 25 foot wide section will become a 1000 sqft living area with 40x40 left for my shop.

My question is, with 8 foot truss spacing, what is the best way to add beams in between to attach the ceiling in the living side? There will be a wall that can be load bearing at 13' off the back wall, so i need to span 13' and 27'. Also, how would i attach the beams at the ends where the roof slopes down?

It will have ceiling rated trusses and i want to get my air handler up there too.

 

[GMCGarage]

Im not sure I follow. can you do a drawing? Why are the trusses 8' spacing, why not 24" oc and just do 5/8 dryawall for your ceiling?

 

[Adittmer]

Yeah have the trusses set @ 2ft if you still can. Made this change to our barndominium last minute and I'm sure glad we did! here is a pic before they finished the Sheetrock divide wall from shop to living space!


Sent from my iPhone using Tapatalk

 

[tomroblee]

It's going to be hard to divide 64' into two sections of 40' and 25'.

For hanging a ceiling you should attach some sort of "beam" or "nailing strip" at a 90 degree angle to the bottom cord of the truss. They could be attached to the bottoms of the truss or be "book shelved" between the trusses. Just make sure that your trusses are rated for whatever you intend to do.

 

[larry_g]

I'm with Admitter, change your truss system to allow the ceiling. Design in the features you need before starting to build. In my case I left out a truss set and went with rafters to get what I wanted. I also had two poles in the middle of the building to allow the change.

lg
no neat sig line

 

[theoldwizard1]

Yeah have the trusses set @ 2ft if you still can.

Trusses at 24" O.C. would be the best for hanging a drywall ceiling. You could do 48" O.C., but you would have to add more blocking (16" ?).

 

[mrpizza]

Im not sure I follow. can you do a drawing? Why are the trusses 8' spacing, why not 24" oc and just do 5/8 dryawall for your ceiling?

Because its a pole barn i am going to add the apartment to, and i was trying to think outside the box.

It's going to be hard to divide 64' into two sections of 40' and 25'.

Well it wont be a full 64 inside either when you account for the walls and space the poles take up. I meant to put 39.

 

[mrpizza]

I will be doing 6" tonge and groove wood for the ceiling throughout

 

[James-W]

I would go with the 24 inch on-center trusses. It will cost more initially, but think long term it will be well worth the extra money.

 

[lukedwag]

Do these trusses even have enough capacity to support that much load from the bottom at 8' on center? What are you using for purlins on the roof ?

 

[mrpizza]

Purlins are 2x4 spec. I will ask to have trusses added 24" oc in the living side. I priced lvl beams and it seems like a wash in cost. Admitter's build looks like what I am up to.

The regular 8' oc trusses were ceiling load rated to add a metal ceiling i believe.

 

[mrpizza]

The barn will be 64 wide. 25 of that width will become the living area.

 

[moneypit_k5]

There is no way running truss's at 24" OC is going to be more cost effective then just framing in between between 8' OC truss's with 2x4 or 2x6.

Just frame in between your 8' span with joists. hanger them, or just nail thru the truss.

 

[lakeroadster]

Then why isnt this done all the time?

It is done all the time, for a barn with a free span roof design.

• It provides clear unobstructed space from the floor all the way to the roof purlins.
  
• It allows for clear unobstructed storage area if the trusses are designed for a storage area

______________________________________________________________________________

OP: 8 ft truss spacing is a great design, as discussed above.

You should not simply "add joists and hangers" to span that 8' distance unless the trusses are designed for that type of loading.

It will have ceiling rated trusses and i want to get my air handler up there too.

Look at the truss drawing. The lower chord rating typically will be at least 10 PSF if they are designed for a ceiling... BUT

... since you are going to use tongue and groove wood for the ceiling you need to calculate the weight of the:

• Tongue and groove wood,
• the vapor barrier,
• the insulation,
• and the joists and hangers
• and look where the air handler will go, and spread that weight out to meet the truss specifications.

to determine what the lower chord rating needs to be for your application.

You should also follow the tongue and groove wood manufacturers recommendation for spacing of supports. This will tell you what the joist spacing should be.

 

[moneypit_k5]

True points. However, the lower cord of a truss is often spanning 8' or more unsupported, engineered or no. Spanning 8' with a 2x4 or 2x6 is more than strong enough to hold a ceiling load.

Also depends on what sort of truss the op is using, be it 2x6 cord or 2x4. Double girt, or single.

 

[lakeroadster]

True points. However, the lower cord of a truss is often spanning 8' or more unsupported, engineered or no. Spanning 8' with a 2x4 or 2x6 is more than strong enough to hold a ceiling load.

Also depends on what sort of truss the op is using, be it 2x6 cord or 2x4. Double girt, or single.

The OP has trusses that span 40 ft.

The truss upper chord / lower chord ratings are what drives the design of those 40 ft trusses. Material types and sizes are based on the rating.

The truss spacing is 8 ft. Adding joists that span from one truss to another may overload the truss lower chord.

 

[moneypit_k5]

I was under the inpression the truss's and building was already underway. Perhaps i misunerstood, but i thought the truss already ordered was designed for a bottom cord ceiling load. My opinion comes from many years as a general contractor, framing houses.
Perhaps folks havent priced out a 60' clear span truss, they are not for the faint of heart.

Even simply doubling up every 8' would be preferable to clear spanning every 24" o/c.

 

[GMCGarage]

Purlins are 2x4 spec. I will ask to have trusses added 24" oc in the living side.......

Problem solved. Best solution.

 

[moneypit_k5]

Problem solved. Best solution.

Dont mean to nitpick, i read that comment as well. Perhaps the OP mis spoke, but purlins are the material that spans the trusses. They sit on edge on top, its what the roof screws down to. Purlin is not to be confused with a part of a truss.

 

[GMCGarage]

Dont mean to nitpick, i read that comment as well. Perhaps the OP mis spoke, but purlins are the material that spans the trusses. They sit on edge on top, its what the roof screws down to. Purlin is not to be confused with a part of a truss.

Yes I know, I was pointing out he was going to have trusses spaced at 24" at the location he will be having ceiling. Purlins are usually on the outside for roof support or wall support, obviously a lightly loaded roof! Wind load must not be that much either.

I missed this post too, and went on to try and explain this was the best option.

I deleted all my other posts.

 

[mrpizza]

I am getting the quote changed to reflect extra trusses in that area. Its looking like about $1500 added cost for this, but worth it to know its done correctly.

This is still in planning stages, i am ironing out the last little details like this one. Thank you all for the good information so far!

 

[mrpizza]

The quote says truss 31 psf total and bottom chord 7 psf. 2x4 roof purlins on 20" centers. Spoke to the builder to update quote and he said exactly what moneypit k5 said, just go between the trusses with 2x6 on hangers. Said they do them all that way.

I have calculated the ceiling materials and insulation at 4-5 psf max.

 

[lakeroadster]

I have calculated the ceiling materials and insulation at 4-5 psf max.

You have to add in the weight of the 2x6 joists and hangers also.

 

[GMCGarage]

I am getting the quote changed to reflect extra trusses in that area. Its looking like about $1500 added cost for this, but worth it to know its done correctly.

This is still in planning stages, i am ironing out the last little details like this one. Thank you all for the good information so far!

The quote says truss 31 psf total and bottom chord 7 psf. 2x4 roof purlins on 20" centers. Spoke to the builder to update quote and he said exactly what moneypit k5 said, just go between the trusses with 2x6 on hangers. Said they do them all that way.

I have calculated the ceiling materials and insulation at 4-5 psf max.

1. did the original truss include 40plf (8'-0" x 5psf) for the extra load?
a. If yes, then go to 2.
2. Can your contractor frame in between the trusses for less than the difference to add trusses ($1500)?
a. If yes, then go back to 8'-0" centers.
b. If no, then you are cheaper to add trusses.
3. If the original truss didnt have the bottom chord load (or air handler load) then ask them for a new quote.
Start back at 1 and see what is cheaper.

Now, If you have an 8’-0” truss spacing, and framing in between, do you think its wise to only design that framing for 5 psf? More than likely you will load it up, unless you are not having access. But with a air handler up there, you will have access.

Need to think all this through.

 

[mrpizza]

The only thing up there will be the air handler. I am not adding any decking for storage.

I am also doing the entire build on the inside to include framing between the trusses.

 

[lakeroadster]

...

Now, If you have an 8’-0” truss spacing, and framing in between, do you think its wise to only design that framing for 5 psf? More than likely you will load it up, unless you are not having access. But with a air handler up there, you will have access.

Need to think all this through.

Good point: The capacity of the joists and their attachments that are spanning between the lower truss chords should be equal to or greater than the truss lower chord rating.

 

[theoldwizard1]

The quote says truss 31 psf total and bottom chord 7 psf.
.
.
.
I have calculated the ceiling materials and insulation at 4-5 psf max.

If "total" means the dead load (weight of the truss, roof decking and shingles) plus the live load, you have very little left over, hence the 7 psf on the bottom cord.

If the ceiling (6" tongue and groove wood) and insulation are 5 psf, you have no margin of error or extra for some one to be crawling around up there, running wire or blowing insulation.

I would go 16" o.c. or ask them to design the trusses in that area for more than 31 psf toal.

 

[lakeroadster]

If "total" means the dead load (weight of the truss, roof decking and shingles) plus the live load, you have very little left over, hence the 7 psf on the bottom cord.

If the ceiling (6" tongue and groove wood) and insulation are 5 psf, you have no margin of error or extra for some one to be crawling around up there, running wire or blowing insulation.

I would go 16" o.c. or ask them to design the trusses in that area for more than 31 psf toal.

Going 16" on the joists will not increase the 7 PSF capacity of the truss..

 

[moneypit_k5]

Wizard Your math isnt quite accurate. The weight of the truss has nothing to do with load capacity. It means load capacity. The weight of the truss falls on the walls, or in the case the posts. Load gets tricky when comparing roof load and inside ceiling load. From an engineerin standpoint, when load is applied to the top of the truss, the bottom cord is tightened, giving it more strength. Thats a whole nuther can of worms.

 

[theoldwizard1]

I am not going to argue with you guys. I don't agree, but I won't waste the bandwidth.

I think the OP need to get the engineers to "beef up" (or at least get the pros to validate the capacity) the live load (ceiling and insulation are live loads because they are not part of the truss) carrying capacity of the trusses because his own calculation of tongue and groove pine ceiling plus insulation is 5 psf, which is more than drywall and insulation.

 

[mrpizza]

Drywall, cellulose, joists, hangers adds up to 4 psf and some change, 4.2 is as exact as I can figure.

There arent any engineered plans. Only permit i have to get is for the septic. The builder of the barn is the best in the area. I have seen his work first hand many times, he certainly isnt the cheapest of quotes I got.

 

[moneypit_k5]

Live load vs dead load. Live load refers to dynamic loads - People walking, snow, ice, etc. dead load describes the weight of the roofing and other materials which the truss must carry. Again Nothing to do with the weight of the truss.

 

[GMCGarage]

The only thing up there will be the air handler. I am not adding any decking for storage.

I am also doing the entire build on the inside to include framing between the trusses.

Just for our curiosity, What are the prices for

trusses at 24"?

trusses at 8'-0" and 2x4(or6) infill in your roof?

How much cheaper is one vs the other?

 

[mrpizza]

I know that trusses and infill 8' spacing is cheaper than adding all the trusses at 24". I dont have an exact cost figured. I sent the builder an email requesting costs to increase the rating on the trusses.

 

[mrpizza]

Here are my sketches. First one is the living area. Trusses run long ways across this front to back. One square is 1 foot.

Second picture shows the whole shop/apartment layout.

Air handler will be in the area above the junction between the bathroom and bedrooms

What is the best method to thermal break the slab at the wall between shop and living area? living area will have radiant floor heat but the shop will not.

 

[lakeroadster]

What is the best method to thermal break the slab at the wall between shop and living area? living area will have radiant floor heat but the shop will not.

Put a construction joint in the slab and insulate between the two slabs. This wouldn't even be visible if you place it right under the wall.

For more data on construction joints see post #155 here: http://www.garagejournal.com/forum/showthread.php?t=289293&page=8

 

[Radix2]

I know that trusses and infill 8' spacing is cheaper than adding all the trusses at 24". I dont have an exact cost figured. I sent the builder an email requesting costs to increase the rating on the trusses.

This is surprising to me.

The trusses are built in a plant with mass production, in a jig, with simple labor.

Infilling the ceiling and purlins on the roof takes about the same amount of wood. At 2' trusses will be lighter weight. but there is a ton more work for the framers to replicate all the structure that 2' trusses give...

It is far easier to set trusses then it is to infill and nail purlins - more measurements, working at heights, hangers, joints, cuts, etc.

Any sheathing under roof metal ?
need to upside your wall headers since the load is between the poles ? - factors to consider that will add extra to the truss fix.

Anyway your builder is experienced, it should be simple for him to say which is cheaper...since it is his labor vs. the truss cost.

 

[mrpizza]

Im waiting on cost to add trusses. I know my cost to frame between. I am doing all the framing after the basic barn is up and slab poured.

I base my earlier statement on the fact that he told me trusses are about $350 per and I would need 12 in that area.

2x6 8 foot long are about 5 bucks or less. I would need 57 of them. Hangers are 3 bucks. 114 of them. Seems much cheaper than 3 grand or more in extra trusses.