Pole barns and attic trusses

[FredWurlitzer]

After a thorough search on here, I haven't really found the answer to what I'm looking for in regards to attic, or storage space, above a pole barn. Is it not common practice to place attic trusses on top of pole/post frame construction?

What is needed in terms of a header along the sidewalls (length of the structure, or eave ends) to support attic trusses, in addition to a snow load? A double 2"x8"? A double 2"x10"? If so, how are they applied to the poles? Is conventional stick framing the only option in this scenario?

Pictures of examples would be great if anyone has done attic trusses with a pole barn. I've considered reaching out to pole/post frame barn builders to get their thoughts on this topic, but figured I would do a preliminary check on here first to get a semi non-biased opinion.

 

[Chuckster in NJ]

Trusses must be engineered for the specific application. A sealed engineered set of truss plans is a must and the truss company will build the trusses from there. Some building departments require these sealed plans prior to issuing permits.

 

[Bigblockyeti]

How wide are you going and what size attic are you looking for? I haven't even poured my concrete for my 16'x22' shed and I'm already thinking about a 36'x50' shop up the road at my property. I like the look of a traditional barn but I also like the initial cost of a pole building. Gambrel attic trusses give me the look, the free span and a pretty big attic area but placing them on a pair of 2x12's with an 8"x8" every 8' around the perimeter sure as heck isn't going to work. I know at some point you can find a heavy enough LVL to support just about anything for any scenario but it's not going to be cost effective vs. traditional stick framed walls with very much overhead weight.

If you're looking at a pole building company, I'm guessing someone could point you in the right direction. When you get it figured out, please share.

 

[FredWurlitzer]

How wide are you going and what size attic are you looking for? I haven't even poured my concrete for my 16'x22' shed and I'm already thinking about a 36'x50' shop up the road at my property. I like the look of a traditional barn but I also like the initial cost of a pole building. Gambrel attic trusses give me the look, the free span and a pretty big attic area but placing them on a pair of 2x12's with an 8"x8" every 8' around the perimeter sure as heck isn't going to work. I know at some point you can find a heavy enough LVL to support just about anything for any scenario but it's not going to be cost effective vs. traditional stick framed walls with very much overhead weight.

If you're looking at a pole building company, I'm guessing someone could point you in the right direction. When you get it figured out, please share.

Lets say a 28'-32' span, 7/12 roof pitch and 8' pole/post spacing. The attic space will be unfinished, unheated and used strictly for storage.

 

[FredWurlitzer]

Trusses must be engineered for the specific application. A sealed engineered set of truss plans is a must and thruse truss company will build the trusses from there. Some building departments require these sealed plans prior to issuing permits.

Understood, but my question is... what is the general requirement for pole/post framing to support those trusses? Also, whether it is 2', 4' or 8' truss spacing.

 

[like2wheel]

Lets say a 28'-32' span, 7/12 roof pitch and 8' pole/post spacing. The attic space will be unfinished, unheated and used strictly for storage.

I have attic trusses in the front part of my barn, 24' wide, 12' pole spacing 6/12 pitch. They sit on 2) 2x12 carriers each side.

I do wish I asked for 8' pole spacing, but so far it's been solid. I have a 24 x 9 room & it's pretty full with a center isle.
Builder told me 40lb/sf.

Hope this helps.

 

[rburke65]

I don’t understand why anyone would go to 12’ spacing.what would the cost be to add a po#t in between ? What great fortune could you possibly be saving with a 12’ span.

 

[RTBS]

Understood, but my question is... what is the general requirement for pole/post framing to support those trusses? Also, whether it is 2', 4' or 8' truss spacing.

The truss spacing depends on the design of the trusses. Often times in pole barns there is a double truss at the poles and purlins (2x8's or something like that depending on the span and load) in between the trusses. With attic trusses you probably wouldn't be able to place them just at the posts, again depends on a few factors like span, loading, etc. The post size depends on spacing and load. The posts are typically sized to resist lateral (wind and seismic) loads as the controlling those typically control the design over gravity loads. I would recommend that you have your structure designed by an engineer either from a pole barn company or independently. So you can account for all of the above. Theres more to it than just selecting lumber. Pole barns are more complex than most small to mid-size homes. Not sure where your located but your local building department may require it to be desogned and stamped by a professional engineer. They do in my area unless its purely agricultural. The trusses should be designed by a truss engineer that is also a professional engineer. Best of luck with your project.

Sent from my SM-G975U using Tapatalk

 

[rayra]

typically the trusses sit atop your poles/posts and the poles/posts are spaced 4' apart. Then your roof purlins are typically 12'-14' and staggered to each tie three trusses to each other.

That's my understanding from researching various designs in planning my own future barndo.

but the OP says 'attic trusses' rather than a more usual 'roof trusses', so I infer he might literally mean attic trusses, which are a bit different and imply carrying much more weight than just a roof / snow load. And that's a steeper roof pitch and greater loading which might necessitate closer truss spacing. And then the question of what the top sill framing will be, to support the additional trusses between the poles. And that's all engineering.

 

[finn]

When I built my 32x54 a number of years ago, I was working with three different builders when setting up specs. The consensus among the three was that if I wanted attic trusses, I should go with conventional stick construction rather than post construction.

Two of the three are large contractors. The third was a small operation.

The reason given was that conventional construction resists racking better in high wind and heavy snow loads, and attic storage loads 13+ above the ground hurt building stability.

Don’t know that’s true, but it’s more than a coincidence that all three had the same recommendation.

 

[James-W]

When I built my 32x54 a number of years ago, I was working with three different builders when setting up specs. The consensus among the three was that if I wanted attic trusses, I should go with conventional stick construction rather than post construction.

Two of the three are large contractors. The third was a small operation.

The reason given was that conventional construction resists racking better in high wind and heavy snow loads, and attic storage loads 13+ above the ground hurt building stability.

Don’t know that’s true, but it’s more than a coincidence that all three had the same recommendation.

I am not an engineer so my opinion on this matter is pretty much worthless. But my opinion, worthless as it may be, is that what they said is most likely correct, at least it certainly sounds correct to me.

 

[bighouse01]

Hi, I just built what you are talking about. I’m in southeastern NY. My building is 28x
40. The attic trusses are 30’ long for a 1’ overhang. Attic trusses are spaced every 24” my barn is sheathed in OSB, 5/8 on the roof, 1/2 on the walls - shingled and sided. The poles are every 8’. Except where the garage doors are, they are spaced accordingly. Stair case up the gable end. On the gable ends are the same attic trusses with girts filling in the attic space is so it can be sheathed or a window installed. The stair case is installed on the gable end against the wall. Where the attic space begins, there is a doubled up truss.

The truss carriers are 2x12 one is installed on the outside of the poles. The one on the inside is the one that is CRITICAL. This inside 2x12 sits where the pole is notched 1-1/2” so the 2x12 sits directly on the pole.

I’ll see if I can post up a pic later.

Between the truss carriers there is a 2x4 sticking up where they nailed the truss to, so it is not only toe-nailed.

 

[bighouse01]

Also a pole barn shouldn’t rack with poles that are 4 feet it the ground and then locked in with concrete.

Farmers are building these 60’ wide and 100 or so feet long and larger. Go ahead and try to do that stick built with a foundation. You’ll go broke!!

 

[wbclassics]

When I quoted out my barn (36x72) with attic truss over the front section (36x32), no one had issues putting the 7/12 attic truss on a pole barn setup, and that included Finger Lakes Construction who has their own in-house engineering department... and I actually believe they spec'd the pole spacing at 9', which is their preference for some reason; FLC tends to work in 3' increments. I did not end up using FLC, not because I had any technical reason to, but rather they just didn't seem interested in residential pole barns at the time... sales staff was hard to get a hold of, took a while to get quotes and relevant info, etc.

So my construction is actually with poles on 8' centers. The trusses are engineered, but what I found out about most pole barn builders is that the rest of the structural specs are based on their intuition or what other builders do. Basically outside of the trusses, pole barn structures in their entirety from independent builders don't get much engineering attention. So I once I had a set basic plans, I ended up doing a lot of calculations myself to insure that parts of the structure were adequate and satisfactory to me. For instance increased the pole size from 3ply 2x6 to 3ply 2x8, and increased the poured pad size for the columns form 18" & 24" to 30" & 36"... because a soil bearing capacity test was lots of money ($3500), so it was just easier to take the lowest bearing capacity and size the pad for that.

Headers on 2x12 SYP #1 on the outside and inside of every column. The outside header is integrated into a truss style panel, where the inside header covers the span between columns without helpers. These outside truss panels did carry engineer stamps on each panel but I'm really skeptical of whether my builder actually conveyed to the truss panel engineers what the panel headers were actually carrying and thus whether the loads used for calculating them were accurate.

So my best piece of advice, and one I wish I would have followed myself, is use a builder or pole barn construction firm that has their own complete in-house engineering department or at least engineer, to insure that the entire building structure is adequate for all loads being imposed on all structural members... not just the trusses. Engineer stamp on the trusses is pointless if walls/columns/footing pads can't handle the maximum loads that the trusses are designed for.

Pic of my truss style wall panel, this is one of the ones that supports the attic trusses. Panels get screwed to the columns using 3.75" long Headlok structural panel screws.

 

[Natty Bumppo]

I am in year 3 of building a 25x35 pole barn with attic trusses. My poles are about 8' apart on average. I used double 2x12 headers notched into the posts. The trusses are 12:12 and spaced 2' OC. I used a metal roof and thus have almost no snow load.

You can see my full build thread here:

https://www.garagejournal.com/forum/showthread.php?t=437779

 

[finn]

I am in year 3 of building a 25x35 pole barn with attic trusses. My poles are about 8' apart on average. I used double 2x12 headers notched into the posts. The trusses are 12:12 and spaced 2' OC. I used a metal roof and thus have almost no snow load.

You can see my full build thread here:

https://www.garagejournal.com/forum/showthread.php?t=437779

Looks pretty sturdy.

The other part of the equation was that at, best, the cost was a wash between pole and floating slab with stick walls foe my size building (32x54) if I wanted to insulate and finish the building interior eventually.

I ended up with stick construction wit attic trusses, which in my case, were a waste of money.

I, for some weird reason, still like the interior look of an unfinished pole building.

 

[FredWurlitzer]

but the OP says 'attic trusses' rather than a more usual 'roof trusses', so I infer he might literally mean attic trusses, which are a bit different and imply carrying much more weight than just a roof / snow load. And that's a steeper roof pitch and greater loading which might necessitate closer truss spacing. And then the question of what the top sill framing will be, to support the additional trusses between the poles. And that's all engineering.

Yes, this is exactly the information I'm looking for. In particular, how robust must the pole framing be to support attic trusses. If we could narrow it down to "X number of feet between trusses with pole spacing being X feet", that would be even better.

 

[FredWurlitzer]

When I built my 32x54 a number of years ago, I was working with three different builders when setting up specs. The consensus among the three was that if I wanted attic trusses, I should go with conventional stick construction rather than post construction.

Two of the three are large contractors. The third was a small operation.

The reason given was that conventional construction resists racking better in high wind and heavy snow loads, and attic storage loads 13+ above the ground hurt building stability.

Don’t know that’s true, but it’s more than a coincidence that all three had the same recommendation.

I have/had a feeling that this may be the suggestion from some builders.. which is to go stick framing if I want attic trusses.

I'm not totally buying into that notion though. I don't see why you couldn't use these trusses if your pole framing was stout enough to handle them. Especially if you used OSB sheathing on the exterior.

 

[FredWurlitzer]

Hi, I just built what you are talking about. I’m in southeastern NY. My building is 28x
40. The attic trusses are 30’ long for a 1’ overhang. Attic trusses are spaced every 24” my barn is sheathed in OSB, 5/8 on the roof, 1/2 on the walls - shingled and sided. The poles are every 8’. Except where the garage doors are, they are spaced accordingly. Stair case up the gable end. On the gable ends are the same attic trusses with girts filling in the attic space is so it can be sheathed or a window installed. The stair case is installed on the gable end against the wall. Where the attic space begins, there is a doubled up truss.

The truss carriers are 2x12 one is installed on the outside of the poles. The one on the inside is the one that is CRITICAL. This inside 2x12 sits where the pole is notched 1-1/2” so the 2x12 sits directly on the pole.

I’ll see if I can post up a pic later.

Between the truss carriers there is a 2x4 sticking up where they nailed the truss to, so it is not only toe-nailed.

Great! I may be reaching out to you regarding your build.

What size poles did you use? Did you notch them? What did you do at the corners in regards to the truss carriers? Are your beams solid sewn beams or laminated? Roof pitch?

 

[FredWurlitzer]

When I quoted out my barn (36x72) with attic truss over the front section (36x32), no one had issues putting the 7/12 attic truss on a pole barn setup, and that included Finger Lakes Construction who has their own in-house engineering department... and I actually believe they spec'd the pole spacing at 9', which is their preference for some reason; FLC tends to work in 3' increments. I did not end up using FLC, not because I had any technical reason to, but rather they just didn't seem interested in residential pole barns at the time... sales staff was hard to get a hold of, took a while to get quotes and relevant info, etc.

So my construction is actually with poles on 8' centers. The trusses are engineered, but what I found out about most pole barn builders is that the rest of the structural specs are based on their intuition or what other builders do. Basically outside of the trusses, pole barn structures in their entirety from independent builders don't get much engineering attention. So I once I had a set basic plans, I ended up doing a lot of calculations myself to insure that parts of the structure were adequate and satisfactory to me. For instance increased the pole size from 3ply 2x6 to 3ply 2x8, and increased the poured pad size for the columns form 18" & 24" to 30" & 36"... because a soil bearing capacity test was lots of money ($3500), so it was just easier to take the lowest bearing capacity and size the pad for that.

Headers on 2x12 SYP #1 on the outside and inside of every column. The outside header is integrated into a truss style panel, where the inside header covers the span between columns without helpers. These outside truss panels did carry engineer stamps on each panel but I'm really skeptical of whether my builder actually conveyed to the truss panel engineers what the panel headers were actually carrying and thus whether the loads used for calculating them were accurate.

So my best piece of advice, and one I wish I would have followed myself, is use a builder or pole barn construction firm that has their own complete in-house engineering department or at least engineer, to insure that the entire building structure is adequate for all loads being imposed on all structural members... not just the trusses. Engineer stamp on the trusses is pointless if walls/columns/footing pads can't handle the maximum loads that the trusses are designed for.

Pic of my truss style wall panel, this is one of the ones that supports the attic trusses. Panels get screwed to the columns using 3.75" long Headlok structural panel screws.

Your laminated poles, are they in the ground or do they rest on a "perma-column" type post/bracket?

Also, if you have any pictures of how the truss panels were applied that would be great.

 

[wbclassics]

Your laminated poles, are they in the ground or do they rest on a "perma-column" type post/bracket?

Also, if you have any pictures of how the truss panels were applied that would be great.

I used PostProtector HDPE sleeves on my glulam posts. They're OK, but if I were to do it over, I would use PermaColumns or pour a proper stem wall foundation.

All wall panels were attached to the posts using 3.75" long Headlok structural panel screws. Likewise on the roof, 3.75" long Headloks were used to fasten roof panels into the trusses, and then at the corner of each roof panel, 6" Headloks were used to fasten the roof panels to one-another. I think we went through about $1500 in Headloks on this project (about 20 bins), and i had some left over.

The attached photo of the installed wall panels is from Day #1 of the walls panels being installed. They put half the number of Headloks in at this point, just to get the panel in position and secure the header of the panel so they could get the trusses on. Then at some point when there was some less involved labor for the crew, one of the crew would go around and finish off the each of the panels with additional Headloks. Roughly 30 Headloks per the 12' panel, and on the taller 17' panels at the rear of my barn about 50 Headloks per panel.

Despite the crew being familiar with this system, driving that many Headloks takes a ton of time. I suspect that was part of the reason they would install the panels with an initial number of Headloks in a few places on each panel, then move to the next panel. And then whenever was convenient down the road one of them would go around the building and finish off a panel with the remaining Headloks required.

 

[FredWurlitzer]

Few more questions to piggyback off of my initial questions:

-What is the technical term for what the trusses rest on? Headers, truss carriers or are the two terms interchangeable?

-Is there any data to show whether or not the double 2x12s are better off laminated together and notched to the exterior portion of the poles? How about one notched into the exterior side and the other notched into the interior?

-I see the general consensus is that laminated poles are stronger than solid sawn. Can you notch laminated poles to fit the truss carriers like people do with solid sawn?

-When "bookshelf" girts are used, are exterior girts necessary? Or can you rely just on the bookshelf girts for framing between the poles?

If you can't already tell, I'm wondering if I can use laminated poles notched at the top for a header/truss carrier. And then follow up with bookshelf girts.

 

[like2wheel]

No need to notch laminated posts; you just leave the inner & outer lams short by the dimension of the truss carrier.
I have bookshelf girts without exterior girts.

 

[FredWurlitzer]

No need to notch laminated posts; you just leave the inner & outer lams short by the dimension of the truss carrier.
I have bookshelf girts without exterior girts.

I see what you're saying.. so how would you attach your truss carrier to the poles?

 

[like2wheel]

You would nail them to the center board, they would bear on the outer boards.
The pole is built from 2x6's

 

[FredWurlitzer]

You would nail them to the center board, they would bear on the outer boards.
The pole is built from 2x6's

Ahh, I think I know what you're talking about now..

So you're turning the laminated pole sideways? I was under the assumption that the laminated poles need to be oriented with the 2x6's running parallel to the trusses. Can laminated poles be oriented in either way without compromising strength?

 

[aluminumwelder]

Hi, I just built what you are talking about. I’m in southeastern NY. My building is 28x
40. The attic trusses are 30’ long for a 1’ overhang. Attic trusses are spaced every 24” my barn is sheathed in OSB, 5/8 on the roof, 1/2 on the walls - shingled and sided. The poles are every 8’. Except where the garage doors are, they are spaced accordingly. Stair case up the gable end. On the gable ends are the same attic trusses with girts filling in the attic space is so it can be sheathed or a window installed. The stair case is installed on the gable end against the wall. Where the attic space begins, there is a doubled up truss.

The truss carriers are 2x12 one is installed on the outside of the poles. The one on the inside is the one that is CRITICAL. This inside 2x12 sits where the pole is notched 1-1/2” so the 2x12 sits directly on the pole.

I’ll see if I can post up a pic later.

Between the truss carriers there is a 2x4 sticking up where they nailed the truss to, so it is not only toe-nailed.

can you tell me who did the drawings/engineering for your structure? i'd like to hire them for my own similar building? or maybe you can send me your drawings for a fee please?

 

[firebirdparts]

After a thorough search on here, I haven't really found the answer to what I'm looking for in regards to attic, or storage space, above a pole barn. Is it not common practice to place attic trusses on top of pole/post frame construction?

It's not reasonable to expect to get the weight of an attic back to the posts. Two incompatible ideas.

 

[billconner]

One proposal I had for 28 x 32 had posts 8' on center and roof trusses 4', with 4 - 2x12 headers to carry truss. 60psf snow load. No idea what it would have been with another 40 psf for attic trusses.

Every post frame company I talked to said don't do attic, build more on grade. (I can't - zoning set backs.) I plan to stick frame it all with rough sawn and full attic, at the cost of a column in the center, and savings more than half.

 

[aluminumwelder]

One proposal I had for 28 x 32 had posts 8' on center and roof trusses 4', with 4 - 2x12 headers to carry truss. 60psf snow load. No idea what it would have been with another 40 psf for attic trusses.

Every post frame company I talked to said don't do attic, build more on grade. (I can't - zoning set backs.) I plan to stick frame it all with rough sawn and full attic, at the cost of a column in the center, and savings more than half.

what will you be using for the floor joists? 2x12" can span about 16' on 24" centers I've read which means maximum span would be about 32'. if one wants a wider building I guess expensive 14" i joists are the next step up? Just trying to figgure out how you are savign more than half? is that because attic trusses are super expensive? I've yet to get a quote on them.

 

[aluminumwelder]

pole barns with attic trusses are shown on facebook groups all the time. https://www.facebook.com/groups/polebarnsandgarages/

 

[billconner]

what will you be using for the floor joists? 2x12" can span about 16' on 24" centers I've read which means maximum span would be about 32'. if one wants a wider building I guess expensive 14" i joists are the next step up? Just trying to figgure out how you are savign more than half? is that because attic trusses are super expensive? I've yet to get a quote on them.

I have a beam on center so under 14' span, ceiling joists with attic loading, so 2x10s on 16" centers. Center beam is 4 - 2x12. In addition all rough sawn locally - around $0.50/bd ft versus $2.00. Not near my plans but iirc around 6000 bd ft - frame, sheathing, siding. 17 plain trusses alone would have cost more than entire lumber package.

This is storage only - cars, canoes, small trailer, and yard stuff. Not sure what's stored in attic.

I really like having attic floor to frame roof. Ridge is about 8' above deck.

 

[bighouse01]

Attic trusses on a pole barn. I can check but I think it’s 40 lbs sq/ft. By far the best decision I made. Extra money but the added space is phenomenal. The attic room is 13’ wide and 7’-8” At the top

 

[Firebrick43]

what is up with all the zombie threads coming alive here in the past couple of days?

 

[billconner]

I think when discussing attics and their desirability, age is important. We moved 1000 miles recently and despite selling and giving away a lot, also filled 3 - 20 yd dumpsters. And we be still have a lot of stuff. We need to be work harder at deacquisition, not storing more.

Just saying, think about what and how soon you are doing to your kids or whomever will have to clean out your attic.

 

[Hawkerpilot05]

I built my pole barn this way. It is 30'×35.5'. I used storage truss' to span across. Unfortunately I live in the suburbs of MSP and I was required to have it signed off by a structural engineer. The top beam that the truss' rest on had to be a structural engineered beam for load. Attached is a couple of pictures..

 

[aluminumwelder]

I built my pole barn this way. It is 30'×35.5'. I used storage truss' to span across. Unfortunately I live in the suburbs of MSP and I was required to have it signed off by a structural engineer. The top beam that the truss' rest on had to be a structural engineered beam for load. Attached is a copy of my palns.

are you sure you attached copy of your plans? I dont' see them or a way to download???

 

[Hawkerpilot05]

Sorry about that. I meant a picture. I will see if I can find my plans.

 

[billconner]

Just curious if the lvls were proud of posts so they lined up with girts?

Looks good! Thanks for sharing.

 

[FredWurlitzer]

I didn’t realize this thread was brought back to life 2 years later!

I still have yet to build my garage.. but the process is under way. Next is gravel and grading for the pad.

In regards to the attic trusses.. I still plan to go with them. Although I have toyed around with the idea of taller side walls, scissor trusses and a mezzanine. Cost effectiveness, I’m not sure how they compare.

18 attic trusses 2’ OC VS. just 7 scissor trusses plus lumber for mezzanine.