Tag Archives: truss carriers

Truss Spacing for Shingled Roofs

Roof truss spacing seems to be a topic with no consensus. Most Americans live in traditional stick framed houses, apartments or condominiums, where roof trusses (if they were utilized, rather than using dimensional lumber rafters) are most typically spaced every two feet.

Reader CHARLIE writes:

“Dear Hansen Pole Buildings, May I ask how far apart was the Truss placement in your “Re-roofing with Shingles” article? 

https://www.hansenpolebuildings.com/2012/01/re-roofing-with-shingles/

I’m considering a 24’x 36’ pole barn for a recording studio build but would need asphalt shingle type roof. I’m concerned that a suitable design would need additional rafters to meet the 7 lb/sq ft load requirement.

Most designs I have seen are showing the trusses 4’ OC. 

Respectfully, Charlie”

Mike the Pole Barn Guru writes:
In this particular article roof trusses were actually spaced with a pair every 12 feet – directly aligned with sidewall columns. This style of post frame construction affords several advantages:

Fewer holes to dig. There is nothing more deflating than getting down to digging one or two last column (pole) holes and hitting a rock larger than a Volkswagon Beetle! Minimization of holes to be dug reduces chances of underground surprises.

No need for truss carriers (structural headers) between columns in order to support trusses. Structural failures are almost always due to connection issues. Truss carriers rarely have adequate fasteners from header to columns and trusses themselves are rarely anchored sufficiently to them.

By far my most read article of all time has been on pole barn truss spacing: https://www.hansenpolebuildings.com/2011/06/pole-barn-truss-spacing/.

Asphalt shingles need to be installed over asphalt impregnated paper (felt) or ice and snow shield, most usually over OSB (Oriented Strand Board) or plywood. Weak link of this system is spanning ability of this underlying sheathing.

In order to be within spanning capabilities of common sheathing, dimensional lumber roof purlins, on edge, were joist hung between truss pairs, every two feet.

When you order a post frame (pole barn) kit from Hansen Pole Buildings with asphalt shingles, we automatically have our engineers design for this added load, as well as reducing deflection criteria so you end up with a nice, smooth roof. We also take into consideration Building Code requirements to account for a future overlaid reroof (even “lifetime” shingles will not last anywhere near a lifetime).


Considering a shingled roof due to how long they are warranted? You might want to read this article first: https://www.hansenpolebuildings.com/2015/03/shingle-warranties/.

Overhead Door Header Problems

Overhead Door Header Problems (and More)


Reader MITCH in NASHVILLE writes:

“I recently purchased a property that the previous owner had just built a 30×50 pole barn on. It has foil faced double bubble on the roof and walls. I need to heat and possibly cool the space. What are the options for insulating the ceiling? The ridge is vented. There is no soffit and thus no vent there. The trusses are 5ft apart. Your all-seeing wisdom is appreciated.”

There are times I wish I was not what Mitch feels is “all-seeing”, because I find lots of problems in photos building owners are unaware of. 

Back in my post frame building contractor days I would go visit some of our newly constructed buildings, as time and logistics allowed. I generally had very, very good crews and we had an extremely high satisfaction rate from our clients. I would find things wrong (in my eyes anyhow) and send crews out to make repairs. More than once I would field phone calls from clients asking what was going on. They were perfectly happy with their buildings. I would explain to them they might be satisfied, but I was not!

Mitch’s photo shows a frequent challenge posed with post frame buildings where headers (in this case more appropriately known as truss carriers), support trusses between columns. I am not a gambler, but would place money on this not having been an engineered building. Just guessing, this builder used the same size truss carrier for all locations. Usually these truss carriers would be sized to support a single truss centered between two columns. Here, due to door location and width, this carrier supports two trusses, or double what it should have been carrying. 

Look back at this photo – there is a noticeable sag across overhead door top! This same sag will be evident along sidewall eave line outside.

Before any thoughts of insulating are considered, a competent professional engineer should be engaged to design an appropriate repair for this header. Engineer should be advised this header will also need to be capable of handling the weight of a ceiling without undue deflection occurring.

Moving forward, contact the roof truss manufacturer to get a truss repair to upgrade trusses to support at least a five psf (pounds per square foot) bottom chord dead load, with 10 psf being even better. Each truss should be stamped with information of who fabricated them.

Once header and truss repairs have been completed, use white duct tape to seal all gaps present in your roof’s radiant reflective barrier. Without these being sealed, there is a potential for warm moist air to get between barrier and roof steel and condensing.

Place ceiling joists on hangers between roof truss bottom chords every two feet. Your previously engaged engineer can verify if 2×4 Standard ceiling joists will be adequate.

Install vents in each gable end. Placed in the top half of each gable, a net free venting area of 360 square inches or more will be required for each endwall.

Hang 5/8” Type X gypsum wallboard on bottom of ceiling joists, leaving an attic access somewhere towards building center. Have a spray foam insulation installer apply closed cell foam along a two foot strip closest to each sidewall. Blow in fiberglass, cellulose or rock wool insulation across remainder of ceiling surface.

An Oops from a Competitor’s Architect Part Two- Lateral Load

As the Architect Turns

In our previous episode, we left Dan tied to railroad tracks in front of a speeding train….

Well close, we left Dan with a post frame building designed by an architect, with some serious structural connection problems.  Now I am a guy who watches Science Channel’s “Engineering Catastrophes”. I would just as soon we do not view Dan’s barndominium as one of them.

Moving forward from our last article:

It will shred LVL and/or column – wood is your weak link

You need to calculate the area being carried by one beam end beam – on an 8′ beam with 18′ joists you would have 8’/2 X 18’/2 = 36 sft (square feet).

Minimum floor live load (other than for bedrooms) is 40 psf (pounds per square foot) live load and you should figure 10 psf dead load for a total of 50 psf.

36 sft X 50 psf = 1800 pounds at each end of 8′ in this example.

Dan writes:

So I have the table you referenced and I get the load calcs but what I am trying to figure out is how you got to the 7 ledgerlocks per post figure. What is the math to get from that table and the 3600 lbs per eight foot section to the amount of ledgerloks?

And since we have gone down this rabbit hole, should I start to get paranoid that one of my 3 truss carriers is affixed with 60d nails and that I need to do a lateral load calc on that in order to make sure it is properly connected?  My guess is that this design was based on shear as well…

Ugh  this is what goes on in the mind of a DIY builder who is a data analyst by day.”

Mike the Pole Barn Guru responds:

Let’s do a run-down of information from ESR-1078 for 5″ Ledgerlock Fasteners (for those playing along at home Google ESR-1078).

Table 1C specifies an overall length of 5″ and 3″ of thread length. Allowable fastener shear is 1235# which by Footnote 4, “Allowable shear strength values apply only to shearing in the unthreaded shank portion of the fastener”. This would be fastener failure itself. This however is not our limiting value.

Table 2 references withdrawal design values – LVL is not likely to be sucked away from column by wind, so not applicable.

Table 3 is head pull-through design values – these values limit numbers derived from Table 2, again not applicable.

Table 4 is for Lateral Design Values in single shear. It lists a 5″ ledgerlock with a minimum of 1-1/2″ side member thickness and 3-1/2″ minimum main member thickness. As your LVL is 1-3/4″ thick, lateral design values will need to be adjusted downward by X 0.929 to account for a lesser length into column. Most glu-laminated post frame building columns are Southern Yellow Pine (SYP).  SYP has a specific gravity of 0.55, so a RDP could possibly calculate out values approximately 10% greater.

In your case, load is perpendicular to side member, parallel to column grain. Using Z perpendicular to grain and Sg of 0.5, adjusted for lesser depth into main member would give a value of 280# X 0.929 or 260.12#. Assuming an RDP could gain 10% for greater Specific Gravity, value per Ledgerlock would still be only 286.13#

With an 1800# load / 286.13# = 6.29 fasteners.

You might want to invest in having a qualified engineer review your plans for adequacy. Yes, there will be a price however you may have recourse against original provider and/or their architect in the event of significant structural deficiencies.

Had our Building Designer not given Dan bad advice, all of this could have easily been avoided. Hansen Pole Buildings, in conjunction with our third-party engineers has developed a sophisticated proprietary software program called Instant Pricing™. Not only will this system provide required investment for a myriad of design parameters in real time, it also does a complete structural analysis of every component and connection – assuring situations such as Dan has, will not arise.

Addition to House, Stone Floor Moisture Barrier

Today the Pole Barn Guru discusses a post frame addition to a house, whether or not one should use a plastic barrier under the stone floor in a steel building, and the ability of a truss carrier to handle imposed loads.

About Hansen BuildingsDEAR POLE BARN GURU: Hi! We are considering a sizeable addition to our 600 sq ft bungalow style home, somewhere in the neighborhood of 30×40 ft addition. Wondering if it’s possible to do pole barn construction for this addition, and what kind of considerations would need to be made? The current home does have an existing basement with block foundation. I’ve read information regarding attaching a pole barn build to an existing house for use as a garage, but wondering how this scenario changes things? We would work with a licensed designer to draw up plans, and a licensed contractor for the build, but are just in the brainstorming phase at this point. KARI in WILLMAR

DEAR KARI: There are actually no real considerations for post frame not applicable to a stick frame building. You should work with a Hansen Pole Buildings designer for your building shell and we can provide engineer sealed plans for structural portions of the addition. You can work with an independent designer (FYI – there isn’t a category of licensing for designer) or create an interior layout of your own.

DEAR POLE BARN GURU: Should I put plastic down under the stone floor in a steel building? BOB in WYALUSING

DEAR BOB: It certainly would not harm anything and will help to minimize condensation issues. Look at a 15ml thickness. For more information on vapor barriers see: https://www.hansenpolebuildings.com/2017/11/vapor-barriers-slabs-grades/

 

DEAR POLE BARN GURU: Really wondering if a 2×12 SYP MSR 2400 will hold my 32ft trusses 2ft oc poles 6×6 8 oc. 1 2×12 on outside and 1 on inside. Is the 2×12 SYP MSR 2400 strong enough to hold the weight? CHRISTOPHER in CHESTERFIELD

CHRISTOPHER: In answer to your question – maybe. It will depend upon a myriad of factors including (but not limited to) Ps (roof snow load adjusted for slope), Dead loads from roofing, any roof sheathing, truss weight, any ceiling or insulation.

If you are so inclined, you can try this calculation yourself:

complex formulaLOAD (in psf – pounds per square foot) X (½ building width plus sidewall overhang in feet X 12”) X Distance spanned by beam squared (in feet)

Divide this by 8 X 2400 X 2 (for two members) X 31.6406 (Section Modulus of a 2×12) X 1.15 (Duration of Load for snow).

If your resulting answer is less than 1 then your beams will probably work.

Caveats – LOAD is Ps + all dead loads. For steel roofing over purlins 5 psf would be my recommendation. If a ceiling is to be installed a minimum of 5 psf should be added (10 psf being better).

Some important factors other than just strength include deflection (especially if trusses support a gypsum wallboard ceiling), minimum required bearing area and shear force at edge of bearing.

Frequently overlooked is connection of beams to columns. Notching in would be preferred to each face of columns.

Ultimately, RDP (Registered Design Professional – architect or engineer) who provided your sealed plans should be making a determination as to adequacy as well as providing appropriate connections.

 

Prefab Wood Trusses are Sexy

Prefab Wood Roof Trusses Are Sexy Though

In 1952, in Pompano Beach, Florida, an inventor named Carroll Sanford had been experimenting with building prefabricated roof trusses using plywood gusset plates and varying concoctions and combinations of glue, staples, nails and screws. Eventually he conceived of light gauge steel plates with punched teeth to connect wooden members.

If this wasn’t a sexy use of technology, then I don’t know what would be.

A burgeoning pole barn (post frame) building industry was largely aided by this new ability to economically clearspan relatively large distances.

What Hansen Buildings does now and since 2002:

FEATURE: Prefabricated face-to-face doubled roof trusses.

BENEFIT: Provides an engineered solution with clearspan widths of 80 feet and (in some instances) more. Endwall trusses make for quick and easy installation, while maintaining roof slopes.

True double trusses provide increased reliability due to their load sharing capabilities: https://www.hansenpolebuildings.com/2018/09/true-double-trusses/.

EXTENDED READING ABOUT THIS SUBJECT:

My all-time most read article: https://www.hansenpolebuildings.com/2011/06/pole-barn-truss-spacing/

Why most people should not order trusses: https://www.hansenpolebuildings.com/2018/10/why-most-people-should-not-order-trusses/

WHAT OTHERS DO: Another feature with a myriad of possible outcomes. I will defer “how” trusses are attached to columns for a later article.

Theories of roof truss spacing become most generally divided up geographically. These geographic nuances do bleed over from one area to next, so are not cast in stone.

Eastern U.S. places single trusses upon two or four foot centers attached to tops of truss “carriers” – headers spanning from sidewall column to sidewall column. Here are a few words about truss carriers: https://www.hansenpolebuildings.com/2018/10/what-size-truss-carriers/.

Midwest most often opts for a single truss aligned with sidewall columns. Spacing might be as little as 7’6” and as great as 10’.

Going West – expect a single truss each side of sidewall columns with paddle blocks to attach roof purlins. Learn about paddle blocks here: https://www.hansenpolebuildings.com/2012/05/paddle-blocks/.

While Eastern and Midwest post frame buildings generally feature trusses at each end. As one heads west, dimensional lumber rafters are often seen – relying upon building erectors to achieve proper alignment with interior trusses.

WHAT WE DID IN 1980: Back in green lumber land – Lucas Plywood & Lumber fabricated trusses out of green lumber. As spans (and dimensions of top and bottom chords) increased they became phenomenally heavy.For building ends, 2×12 #3 rafters were provided.

 

Correct Pole Size, The Better Building Size, and Drip Edge Placement

The Pole Barn Guru assists with questions about pole size, the “right” sized building, and a picture is worth a thousand words.

DEAR POLE BARN GURU: I have a question on a pole barn.  I’m thinking of 50 by 60 and about 14ft high or so.  On the 4/4 poles, how far apart should they be.  Also on the headers, that are at the top and go all the way around, are they usually 2 by 8?  Thanks, JOE in BOWLING GREEN

DEAR JOE: Hopefully you trust me enough to believe I will steer you in a correct direction, because you are heading in a wrong one. Only one right way exists to get answers you seek, to order yourself a post frame building kit package with plans sealed by a registered design professional (RDP – engineer or architect) specifically for your building (not a generic photo copy). Done right – there will be no need to have headers all around your building, as double trusses should be placed directly to bear upon columns, insuring best possible structural connections. As to columns, they will need to be much larger than 4×4, regardless of how far apart they are spaced.

DEAR POLE BARN GURU: I am trying to design a small hard apple cider production building. It does not need to have a retail portion; that is elsewhere at our farm; just a convenient 20×30 work room that can accommodate lots of washing/spraying down of equipment, temperature control, allow vehicle entry for loading/unloading, and some viewing windows for customers to see the process. Do you have some plans/designs/kit for such a building?

Thanks and kind regards, TOM in ROSE HILL

Hansen VisionDEAR TOM: You’ll want to make certain your proposed 20′ x 30′ area will be adequate for all of your needs. You may find increasing building footprint to say 24′ x 36′ to not be significantly more expensive of an investment, whilst providing 44% more space. With every building we provide being a custom design to best fit client needs, we can certainly provide exactly what you are looking for. A Hansen Pole Buildings’ Designer will be in contact with you shortly.

 

DEAR POLE BARN GURU: 14 foot side wall panels with 2×8 skirt, what is my measurement on the skirt either from top of skirt or bottom to install my rat guard, I will have a 12 inch overhang (eaveside) using fj channel. CARL in NEWAYGOl

DEAR CARL:

 

 

 

 

Engineering Your Pole Building for Free

Please Let Me Engineer Your Post Frame Building For Free

Pole Barn Guru BlogBecause I am not a Registered Design Professional, I can’t engineer your new post frame building for you. And, if I was, I most certainly would not be doing it for free. Typically an engineer should be compensated somewhere in the area of 8 to 12% of the value of the project, depending upon how involved they have to be with it, as well as if a visit (or visits) to the site are included.

Reader TERRY in FORT WAYNE had written and had his original request fly off into cyberspace, so he tried again:

“Mike, Thanks for getting back to me. That doesn’t surprise me!! Questions: 1) My barn will be 44’x32′ x15′ wall height with the trusses running the 44′ way. What size of holes do I need to bore for my post anchors? I’m not barring my post, pouring concrete to the top with 18″ tall “U” brackets made from 1/4″ plate and (4) jay hooks 18″ long on the bottom of brackets that will be in the concrete 18″s. Also what size header do I need on the truss support side if I install trusses every 24″ with plywood and shingles with A 16′ oh door opening .( Wanted to match my existing garage roof.) I will be tying the new barn to the existing garage on one end. If not a good idea what header to use with trusses at 8′ and wood purlin and metal roof? Let me know if you need any more info. Thanks for your help. Dirt is clay and figured at 3-4K in my area.

If you have any questions please call.

Thanks.”

Mike the Pole Barn Guru replies:
You are asking questions of me which should be directed to the RDP (Registered Design Professional – architect or engineer) who designed your building and provided the plans. These will include the foundation design as well as any truss carriers.

Some commentary – there are wet set brackets made specifically for post frame buildings. I would recommend you invest in them rather than trying to fabricate (or have fabricated) your own, unless they were designed by your RDP and inspected by him or her after production. For Clay soils, the Building Code allows a value of only 1500 psf – any greater values should be used only if an onsite soils test has been done by a registered engineer, else you are at risk of settling issues. See Table 1806.2 https://codes.iccsafe.org/public/document/IBC2015/chapter-18-soils-and-foundations.

If you are not too deep into your project and do not have an RDP involved, I would strongly encourage you to deal with a post frame building kit supplier who can provide engineer sealed plans and calculations for your building, along with the materials to assemble it and complete instructions.


 

 

Calling for the Wall Steel Stretcher

Calling For The Wall Steel Stretcher

In our last episode, the dilemma of how to get a smooth roof plane was solved, to the apparent joy of all involved.

However up cropped a new challenge, contributed to by us however pretty much on the builder and this is why.

You may recall the eave height of the building was to be 16 foot and five inches.

Long time readers will recall eave height appears to be a challenge for some of the most experienced readers, so much so as it is indicated no less than five times on every set of Hansen Pole Buildings plans, as well as 51 times in the Hansen Pole Buildings Construction Manual.

For more insights into eave height please read: https://www.hansenpolebuildings.com/2015/02/eave-height-2/.

Our aforementioned Building Wizard decided to ignore the eave height markings found on multiple pages of the engineer sealed plans, and perhaps didn’t open the cover of the Construction Manual. Instead, one of our draftspersons had errantly placed a dimension on the plans for a height to the bottom of an LVL across an overhead door opening – and instead of questioning why this one single dimension did not add up to the multitude of places on the plans which had the correct dimension, he proceeded to construct the building 3 and ½ inches TOO TALL!!

Then he wondered why it was the wall steel was going to be too short!

Well, in order to prevent a major panic and cost, we came up with a solution to increase the height of the fascia by the needed difference. Here is when I got to personally fall into the trap of blunder – as I drew the correct trim on the “fix” drawing and put an incorrect part number with it. This resulted in the wrong trims being delivered to the jobsite and sending the builder off to Rantville.

And the “soffit nailer”? On the plans it is only described as the distance it is located down from the eave height – which is now 3-1/2 inches higher than the plans show. No, the distance from grade did not change, however it did move this distance down from the eave height, in order to make all of the wall steel work.

The fascia trim issue was solved by the client having some custom trims made locally, in exchange for us providing three extra sheets of roof steel to make up for the ones the builder bungled.

In the end, client gets a beautiful new building, builder gets to maintain his ego trip and happiness is maintained in post frame building land.

All’s well that ends well.

Sharing the Pole Barn Blame

Sharing the Blame

Welcome to 2017!

As you may recall, 2016 ended with me sharing an email from a builder who is constructing a new Hansen Pole Building and may possibly be a legend in his own mind.

Our company policy, when a challenge arrives, has always been to begin by looking to see what, if anything did we do wrong. In this particular case, we (and yours truly) share in some of the blame.

For you, gentle reader, I will paint a picture of the building in question, so you may get a better feel for the entire process.

The building is a 40 foot clearspan in width, 100 feet long with an eave height of 16 feet and five inches. It is designed under the 8th edition of the Massachusetts State Building Code, with a 90 mph (mile per hour) design wind speed and a 50 psf (pounds per square foot) design flat roof snow load.

It features 12 inch enclosed overhangs on all four sides, as well as three 14 foot wide by 14 foot tall overhead doors on one sidewall.

The most practical design solution actually (which is a rare case) turned out to be based upon the traditional “East coast” style of post frame construction, with a single truss spaced every four feet on top of “truss carriers” (beams) spanning sidewall columns generally every eight feet (other than at the overhead door locations).

This building happens to be narrow in width in relationship to length (1 to 2.5 ratio) and is fairly tall. As such, the wind load was great enough to exceed the shear resisting capacity of the steel roofing in the eight feet closest to each endwall.

In order to carry the load, the building was designed so the trusses in the affected areas would have a traditional ¼ inch butt cut (educate yourself on what a butt cut is here: https://www.hansenpolebuildings.com/2015/05/truss-butt-cuts/), while the balance of the trusses would have 11/16 inch butt cuts. This would allow for the top of all truss carriers to be placed at the same height, and 7/16” OSB (Oriented Strand Board – https://www.hansenpolebuildings.com/2013/10/osb-versus-plywood/) to be installed on top of the lower heel height trusses.

Pretty darn skippy sounding ……. Until we get to tomorrow!!

Yep – yet another cliff hanger!!

Not a building Under Construction

No This is NOT a Building Under Construction

Here is the story from the building owner…..

“When we pulled up here, about a quarter to 12 last night, is when I noticed I could see some insulation and then I got out and took a walk around and that’s when I saw that we had no roof,” Joel Hildebrandt said.

Hildebrandt is the co-owner of CJ’s Pet Center in Hawley, Minnesota. During the storm, one of his employees was inside when the damage happened.

“A year’s worth of hard work, not just dollars, and the time,” Hildebrandt said.

Hildebrandt says he’s thankful that no one was hurt.

“Everybody was wet, guests included, but everybody was safe,” Hildebrandt said.

The employee was able to survive the damage by hiding in the bathroom, away from windows.

Something everyone should do when the weather turns ugly.

not-under-construction

This building style is what I refer to as a four and eight building – it has columns along the eave sides spaced every eight foot on center, with trusses every four feet supported upon headers (also known as truss carriers).

This is also not a post frame building designed and provided by Hansen Pole Buildings. Our preference is to use a frame system where all of the trusses are doubled and attached directly to the columns. Purlins are attached to trusses with engineered steel hangers manufactured by Simpson Strong Tie (https://www.hansenpolebuildings.com/2013/08/simpson/). We’ve solved the weakest links.

I had addressed a similar structural challenge, in regards to post frame building failures, back in April of 2014: https://www.hansenpolebuildings.com/2014/04/nationwide-2/.

In the case pictured the purlin to truss uplift forces are one-half as much as would this be if trusses were every eight feet.

Still, I have always believed the purlins as fastened typically will not resist the applied uplift loads. The photo proves my point. The roof trusses are intact and still connected to the truss carriers, and the roof steel is still attached to the purlins (just no longer on the building).

When I do an analysis of a failure (or potential failure), I look for the weakest link. More often than not, the weakest link is actually human error.

In the pictured building, the weakest link ended up where I most likely would have guessed it would be.