Tag Archives: prefabricated roof trusses

Can You Provide Just Trusses for My New Pole Barn?

Back in my owning a roof truss manufacturing plant days, we sold trusses to a building contractor, who was uninsured, and new building owner neglected to insure building. When it collapsed due to builder error (building also was not engineered), our insurance company ended up paying for a replacement building as it was ruled we were 0.5% to blame, just because we provided trusses! 1/200th of fault was ours, yet we got billed!! Think trusses are expensive? Blame it on scenarios like this, causing insurance premiums to skyrocket.

To add insult to injury – builder’s check he wrote to us for these trusses, bounced and we never got paid for them!

Reader CORY in EXPORT writes:

“Hello.

Is it possible to just get the trusses or a design on the truss construction. Placement on posts. Thanks!”

Mike the Pole Barn Guru writes:

Thank you for your interest in a new Hansen Pole Building. Our goal is to provide you with a complete, third-party engineered post frame (pole) building including complete plans, assembly instructions and materials delivered to your site.

We do not provide just trusses, as this lends itself to people believing they have an “engineered building” just because they have trusses built from engineer sealed drawings. In event of a collapse due to the balance of the structure not being designed by a RDP (Registered Design Professional – architect or engineer) fingers start to be pointed towards whoever provided the trusses.

As for a “design on truss construction” you truly do not want to tackle building your own trusses at your site. Even if you were to have a prefabricated roof truss drawing to work from – it is impossible to buy most specified lumber grades from a drawing. You also have no way to acquire steel connector plates for the truss assembly and if you could somehow obtain them, you lack an ability to properly press them in. You might possibly be able to come across a substitution of plywood gussets for steel plates, however these plywood gussets would be significant in size and are usually required to be glued with a resorcinol glue (for further reading upon this subject: https://www.hansenpolebuildings.com/2012/10/roof-trusses/).

When it comes to placement (attachment) of trusses to columns, this will be best left to an expert third-party engineer who will seal your building plans. He or she will have the needed education, experience and expertise to properly design all of your building connections to adequately support imposed climactic loads.

If you believe you can somehow save money by piecemealing together your own building, then this will be a must read: https://www.hansenpolebuildings.com/2014/03/diy-pole-building/.

Your Hansen Pole Buildings’ Designer will be in contact with you soon, to assist in your journey to a new post frame building.

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.

 

Post Frame Scissor Trusses

Post Frame Scissor Trusses

I’d spent summers working for my dad and uncles framing buildings and being low man when it came to a totem pole of laborers, I did my fair share of strong back, weak mind work – such as setting trusses. As a teenager, I had not given much thought to complexities involved in engineering trusses. I just knew they could do things we could not possibly stick frame. They made jobsite building assembly go quicker, as long as trusses were correct (a gamble from some manufacturers then).

When I was newly introduced to prefabricated roof trusses as a sawyer back before many of you readers were born (1977), my eyes were opened to an entire world of structural possibilities. My truss buddy Bret Hansen and I were so obsessed with being best truss builders ever, so we spent our own time nights and weekends going to view our trusses upon buildings under construction. We saw slightly sloped commercial trusses, steep sloped trusses, hips, valleys and scissor trusses.

I’ve written about scissor trusses before, with https://www.hansenpolebuildings.com/2016/10/scissors-trusses-post-frame-buildings/ being one of my favorites.

Reader JIM in GRAND RAPIDS triggered today’s musings when he wrote: “Can a pole barn have a vaulted/cathedral ceiling? I have been told NO by one pole barn builder only to see references to using scissor trusses in pole buildings on the Internet. Thank you, GURU, for clearing this up.”

Mike the Pole Barn Guru responds:

Reality check – over half of all builders did not graduate from high school. In this we are talking about a big pool of builders, where those making up a pie piece segment known as pole barn builders may (from personal experience) be even less educated. The builder who told you no, frankly just doesn’t know. Chances are fairly good, if it can be done it wood, it can be incorporated into a post frame (pole barn) building.

25 years ago I had built for myself a rather unique post frame building. Located upon the back portion of our steeply sloped Newman Lake, Washington lot, it’s a one of a kind structure.. Interested readers can find out just a bit more about this building here:  https://www.hansenpolebuildings.com/2012/02/grade-change/.

When my younger brother Mark and I were but tykes, we were introduced to a noble game, ping pong (aka table tennis) by our mother’s dad – Grandpa Boyd. We’d play for hours in their duplex basement, where a low ceiling caused many shots to be caromed off.

In designing my new building, I wanted to make provision for an upper level to be able to be a general purpose rec room, where my then young (now all grown and gone) children could play ping pong without challenges posed by our grandparents’ low ceiling. A solution was as simple as scissor trusses.

In order to match existing house and detached garage rooflines, a 7/12 roof slope was utilized. This lent nicely to being able to have a 4/12 interior scissor truss slope. With a width of 30 feet, room center height approaches 13 feet – plenty enough to do some lobbing with a ping pong ball!

So yes, Jim, you certainly can have a vaulted/cathedral ceiling!

 

Prefabricated Roof Trusses Part One

Prefabricated Roof Trusses – They can Make You or Break You

This article (written by yours truly) was published in the May 2016 Rural Builder magazine (https://media2.fwpublications.com.s3.amazonaws.com/CNM/RB_20160501e.pdf and begins on Page 26). Although the article is written towards post frame (pole) building contractors, it gives a perspective as to the challenges of ordering something as apparently simple as a set of prefabricated roof trusses:

I worked for, managed or owned roof truss manufacturing facilities from 1977 until 1999 – so we only ever had to operate under the pre-International Building Codes, which made our lives easy. Regardless of roof slope, exposure to wind, roofing material, whether a building was heated or unheated, the top chord live load (or roof snow load) was the same within any localized geographic region, with the exception of differences in snow load caused primarily by elevation changes.

When a client brought in a set of plans, we took on the responsibility to insure the quantity of trusses, roof and ceiling profiles, etc., were correct. We looked upon ourselves as being the experts – rather than the builder or building owner who was purchasing the trusses.

Walk in the door of a truss company today with a set of plans for a truss quote and the expectation is the purchaser has to be “in the know”, which I personally find counter intuitive, but it is the current reality.

As a broad generalization, today’s truss manufacturers are looking out for one entity, and it is not the person writing the check to pay for their product.

I am going to share some secrets which should both increase your bottom line as well as allow you to sleep soundly at night.

First – do not assume the truss company is going to do it right. It is better to take the more realistic position of, they will do it wrong. Wrong can result in an increase in the probability of a catastrophic failure, having to pay more than one should, or both.

Secondly – if you are shopping various vendors, the best price on the truss order might not be the best buy for your building.

A little sharing into how to make sure the trusses you order actually meet the required load conditions.

I am going to put in a plug here for Registered Design Professionals or RDPs. If you are constructing post frame buildings, or providing post frame building kit packages, and are not using originally RDP sealed plans, which are specific to the address where the building is being erected, you are seeing the light at the end of the tunnel and the light is a speeding train.

Maybe you have built or provided hundreds or even thousands of buildings and never had a failure. Trust me, the failure is going to come, and may have nothing to do with how the building was designed, but if an RDP did not design it you are placing yourself and your business at a tremendous risk.

On to important stuff, the Building Codes.

The IRC (International Residential Code) is a prescriptive code for stick frame buildings within limited parameters of snow and wind loads. It does not address post frame construction therefore all post frame buildings should be designed using the IBC (International Building Code).

The International Building Code (IBC) identifies the appropriate Ground Snow Load (Pg) to use on a building based upon its location. When jurisdictions adopt the IBC, they should also be designating the Pg value or values within their area of coverage. Some Building Officials are still rooted in the 1900’s and (contrary to the current Code) designate a Roof Snow Load, which often defies the Laws of Physics.

A case in point, not too many years ago, we provided the post frame building kit package for the Nature Center at the Cheyenne Mountain Zoo in Colorado Springs, Colorado. The Building Department gave the ground snow load as 27 psf (pounds per square foot), yet wanted 40 psf as the roof snow load. When our engineer called the Building Department to discuss this, the explanation given was, “The snow is just different here!”

Hmmm, ‘the snow is just different here’. Sounds pretty scientific. How about I give you some guidance as to what to really pay attention to, so your building is not only designed correctly to stay up but also how to save you some money. Sound good? Well, come back tomorrow to read Part II and get those answers… and a whole lot more.

Dear Guru: Altering Roof Trusses

DEAR POLE BARN GURU:Currently constructing building and the roof trusses are not built according to engineered plans. Plans call for 2*10 and these trusses are 2*6. Builder has purchased additional materials to reinforce the trusses.

Now the steel is going up today and found that the 2 11’10” clay endwall pieces are missing. Builder also informed me that there are not any gutter endcaps. SPINY IN SOUTH DAKOTA

DEAR SPINY: Thank you very much for investing in a new Hansen Pole Building kit package last year.

Roof trusses on building plans are typically just an approximation of what the trusses may look like, as the draftsperson does not have the drawings from the roof truss manufacturer when plans are produced. In reviewing the engineer sealed truss drawings from the truss company, indeed 2×6 trusses will carry the loads appropriate for your building.

Either you, or your builder, really should have been in contact with us prior to your trusses being altered. Even though “reinforcing” the trusses may have seemed like a good idea at the time, it is very possible their ability to properly carry the loads has been compromised. A prefabricated truss should never be altered, without the approval of the manufacturer and their engineer.

Weird things do happen from time-to-time, and your steel order happens to be one of those. Our Material Takeoff (which was provided to you last year so you could do inventory) does happen to show the 11’10” pieces, as does our order to the steel company. For whatever reason, the steel company did not process these two pieces and they do not appear on the return paperwork from the manufacturer.

We do provide explicit instructions as to inventorying all materials as they are received by you. You are given 48 hours after receipt to notify us of shortages – for many reasons. Suppliers are paid by us, based upon the Purchase Orders we place, so we have had to pay for the two panels which you did not receive. We also want to prevent construction delays. If we had known these panels were not received by you 10 months ago, with the rest of your order, it could easily have been rectified then.

Even though the missing panels were not reported as expected, we will be providing them to you at no charge.

On the gutter endcaps – we did not provide your gutters, you may want to contact whomever you contacted to provide the gutters

Roof Truss Quality Control

Roof Trusses are structural frameworks, generally two-dimensional, whose members are almost always assembled to form a series of inter-connected triangles, Perimeter members of the assembly are called truss chords and interior members are called truss webs.

Metal plate connected wood trusses (MPCWT) are composed of wood members joined with metal connector plates (also known as truss plates). These metal connector pates are light-gauge, toothed steel plates.

MPCWT are an integral part of most pole buildings. Their use allows for wide cost-effective clearspans and greatly speeds jobsite construction.

Hansen Pole Buildings, like most providers of pole building kit packages, does not fabricate our own trusses. Outsourcing allows us to provide economical solutions which are relatively local to each building site, by holding delivery costs to reasonable levels.

One of our clients recently had some concerns regarding the quality of the trusses received at his site. Each of our clients is provided with a secure individual log-in to their portion of our website, which allows them to quickly and easily upload photos. Using this system, the client provided some interesting photos. Among them were some where the client could fully place his finger between some of the wooden members of the trusses.

Roof TrussesIn a not too distant past life, I owned two truss plants for 17 years. In sum total, I owned, managed or worked in one capacity of another in truss manufacturing companies for over two decades. Truss manufacturers are not only responsible for in plant quality control, they are also subjected to random third-party inspections quarterly. The process is rigorous – no manufacturer ever wants to fail an inspection.

The Truss Plate Institute has a lengthy document governing the entire truss process – including quality control. For those of you who like to read, or have issues falling asleep at night, the ANSI/TPI 1-2007 standard can be read online for free at: https://design.medeek.com/resources/truss/documents/ANSI_TPI1-2007_Standard_and_Commentary-Appendices.pdf

The relevant portions of the document regarding Wood Member-To-Wood Member Gaps is found at 3.7.6.1 of the document:

“Except as indicated in Section 3.7.6.2 or as otherwise specified on the Truss Design Drawing, maximum gaps in all joints except floor Truss chord splices shall not exceed 1/8 in. (3 mm), where the gap is measured at each edge of the Metal Connector Plate for joints in which the plate edge is within the scarf, and measured at the end of the scarf for joints in which the plate edge is outside the scarf. Scarf is the portion of the joint in which it is intended that there be wood-to-wood contact between two Wood Members. The maximum gap for floor Truss chord splices shall not exceed 1/16 in (1.5 mm) across the entire scarf. For joints designed with single points of contact between adjacent members as shown on the Truss Design Drawing, the maximum gap between all contact points shall not exceed 1/8 in. (3 mm).”

Pretty tough requirements!

In the case of these particular trusses in question, the photographs were forwarded to the manufacturer, and their engineer provided sealed documentation of their adequacy. The manufacturer also had a representative make a personal visit to the client to examine the trusses and verify they met with the engineer’s expectations.

Roof Trusses Built with Glue…Really?

My life with roof trusses began in Spokane in the spring of 1977. I spent the first two plus years of my career in Spokane and later Coeur d’Alene, Idaho, before being hired to manage a roof truss plant in Salem, Oregon.

Having never been exposed to anything different, my assumption was all prefabricated roof trusses were assembled using pressed in steel connector plates. My world view, at the time, was fairly narrow – as I found out the largest competitors of my new employer, were building roof trusses which were held together with plywood gussets which were glued onto the truss lumber with Resorcinol glue!

Wood GlueResorcinol waterproof glue is a great (although expensive) product. It is a high performance, two component adhesive which is designed to provide the strongest, most durable bonds in severe service applications. After curing, Resorcinol is unaffected by either salt or fresh water, and other typically corrosive aquatic conditions, as well as outdoor exposure and temperatures ranging from tropical to subzero.

Most often, at least in a form most people are familiar with, it is designed to laminate structural wood beams (glu-lams).

The glue is made from resorcinol, sometimes called resorcin, which is produced when a large amount of resin is softened and combined with potassium hydroxide. Resorcinol in glue form is regarded as highly sturdy and dependable.

When using resorcinol glue, extra care should be taken to ensure the workspace is properly ventilated. Those handling the glue may find face masks necessary due to the pungent odor (alcohol and formaldehyde).

Resorcinol glue will cure at room temperatures (70 to 95 degrees Fahrenheit) and will cure faster at higher temperatures. Poor bonds result from use below 70 degrees – which leaves me now wondering about the long term quality and performance of my then competitors trusses, which were built in unheated buildings year around!

The ideal moisture content of wood being glued with Resorcinol is between 8% and 12%, and bonds on wood with moisture contents above 15% are usually inadequate. As “dry” lumber only has to have a moisture content of 19%, or less, further drying may be required, prior to being manufactured into glu-laminated columns.

Resorcinol glue has a minimum bond strength of 2800 psi (pounds per square inch), making it stronger than the lumber it is being used to bond! This is why a finger-jointed piece of resorcinol glued lumber, when tested to failure, will have the lumber break, before the finger-joint.

Due to glue costs, the need for a controlled temperature environment and strict lumber moisture control may cause manufacturers to produce lessor quality products, which end users and the general public may not realize as being inferior.

Just a sidebar – boating enthusiasts find great benefit in using waterproof resorcinol glue. Whether used in the building of a new boat or the repair of an old one, this type of adhesive is considered to be the best glue on the market. It is so popular and well-respected it is the glue used by the United States Navy on their ships.