Tag Archives: diaphragm screws

Thru Screwed Steel Screws – Pull-Over and Pull-Out

Thru Screwed Steel Screws – Pull-Over and Pull-Out

Hi, my name is Mike, and I am addicted to watching engineering disaster videos.

No, there is not yet a 12 step program for this addiction.

I have learned a few things from my addiction. When it comes to construction failures, most of them come down to connections. Connections (at least when wood is involved) take fasteners – screws, bolts, nails, wooden dowels, etc.

Now if one is getting parts manufactured say in China (as an example), there is a high probability they are going to fail under load – due to manufacturing process shortcuts. Biggest shortcut (and impossible to detect by eye) is under strength material.

When it comes to post-frame construction, most buildings are clad with roll formed steel roofing and siding. It is extremely durable, very cost effective and easily installed by use of thru screws.

At Hansen Pole Buildings, we provide only Diaphragm screws manufactured in Canada using North America components. These screws are a #12 diameter and 1-1/2 inches in length.

Now why would an assembly with a thru screw structurally fail (assuming product is manufactured of proper strength steel)?

Screws could pull out of wood. This would be a problem.

Over three decades ago, at an Alumax testing facility east of Los Angeles (Perris Valley), we constructed a full scale roof to test shear strength of steel panels. Our testing resulted in some surprises. Initially we felt our weak link would be framing under roof steel. We were totally in error and surprised at our results. Our assembly was done to match industry standards and included fastening steel to roof purlins using #10 x 1” screws every nine inches. As we placed horizontal loads into this roof, before ripples even appeared in steel roofing, screws started to pull out of framing. This pull out problem was solved by using 1-1/2” long screws.

Our next problem was roof steel began to slot beneath screw grommets. Solution here was to use larger diameter screws in high stress areas (at eave and ridge) and to place screws in this area on each side of each high rib, rather than along one side only. Only after all of these screw issues were solved, were we finally able to test our steel to failure. These results showed some fairly significant values. This test’s results are published in NFBA’s Post Frame Building Design Manual https://bse.wisc.edu/bohnhoff/Publications/Copyrighted/NFBA_Design_Manual.pdf See Table 6.1 (assemblies 13 and 14).

After our test was completed, Alumax’s design engineer, Merle Townsend, designed a screw specifically to solve weaknesses demonstrated by our test. Labeled as a “diaphragm” screw (https://lelandindustries.com/productpdfs/page%2001.pdf) this 1-1/2” part features a larger diameter shank than standard screws. A side benefit of this screw is this larger diameter helps prevent screw heads from twisting off during installation.

I did some looking at what published pull out values are for those #9 x 1” industry standard screws – only value I could find was 542# and it did not specify species of wood being driven into. Our diaphragm screw has minimum pull out values of 910# (Canadian SPF) and 1060# (Douglas Fir). in some instances – nearly double industry standard!

Besides pull out, another source of structural failure is pull-over. This is where screw remains in wood and steel roofing flies away. Besides washer/grommet configuration of screw, this is also going to be a function of steel panel thickness. Graph on Leland’s website displays a 26 gauge pull-over value of roughly 500#. Converting by dividing by 26 gauge minimum thickness (0.0187) and multiplying by 29 gauge minimum thickness (0.0142) provides a pull over value of about 380#. T

herefor pull-over is going to dictate before pull-out.

(Author’s note – having searched extensively, I have yet to be able to find a published pull-over value for #9 screws.)

For steel panels, screws in field (not ends of panels) are placed every nine inches. With screws into every purlin, spaced 24 inches on center, each screw is carrying 1.5 square feet of load. Our pull-over value of 380# divided by area gives a resistance per square foot of 253#.

Highest wind load areas are at perimeters of roof (Zone 3). At 200 mph (miles per hour) and a wind exposure C (fully open to wind in one or more directions), load on components and cladding in Zone 3 is 163.65 psf (pounds per square foot), based upon mean roof height of 15 feet. Even in wind exposure D (fully exposed to winds coming over large bodies of water) and making mean roof height 20 feet, load would be 208 psf.

Hansen Pole Buildings, having now provided well in excess of 25,000,000 diaphragm screws, has yet to have had a single screw fail in pull-out or pull-over.

Yes, these screws are more expensive, however we enjoy sleeping well at night knowing our clients’ steel cladding is not going to fail due to any screw issue.

Roof Leaks, DIY or Hire Builder, and Building Width

This week the Pole Barn Guru answers reader questions about on old roof that leaks due to nails used in attaching steel, a request for builder referrals, and if a Hansen Building is available in a 48′ width– yes, they are.

DEAR POLE BARN GURU: My older metal barn complete with roofing nails, not screws, leaks badly. If I install eve trim would I use gutters also? Now, the building, 96×40 has neither. It leaks under the eves. Replacing the nails has worked some. KAREN in ELMA

DEAR KAREN: Hansen Pole Buildings’ warehouse is a roughly 50 year old post frame building with roof steel attached with nails and it leaked like a sieve. We used two cases of “super whammy” caulking to try to seal around nails, it helped some, but ultimately our only solution was new roof steel. Although it sounds painfully expensive, it really is going to be your only true solution. When you order new steel, make sure it comes with a factory applied integral condensation control and use 1-1/2″ diaphragm screws to attach (they are larger diameter, powder coated and have EPDM washers).

Continuous seamless gutters are always a good investment, provided you add snow breaks on your roof, if you are in snow country.

DEAR POLE BARN GURU: We are looking for a builder to put up a 70’x40′ pole structure for us — do you have any names of contractors/individuals who have put a Hansen building in the area? ESMEE in WENATCHEE

DEAR ESMEE: Your new building kit is designed for the average physically capable person, who can and will read and follow instructions, to successfully construct your own beautiful building shell (and most of our clients do DIY – saving tens of thousands of dollars). We’ve had clients ranging from septuagenarians to fathers bonding with their teenage daughters erect their own buildings, so chances are – you can as well!

Hansen Buildings Construction ManualYour new building investment includes full multi-page 24” x 36” structural blueprints detailing the location and attachment of every piece (as well as suitable for obtaining Building Permits), the industry’s best, fully illustrated, step-by-step installation manual, and unlimited technical support from people who have actually built post frame buildings. Even better – it includes our industry leading Limited Lifetime Structural warranty!

Currently (and for the foreseeable future) there is a nationwide shortage of building erectors. Many high quality erectors are booked out into 2023. We would strongly encourage you to consider erecting your own building shell.

For those without the time or inclination, we have an extensive independent Builder Network covering the contiguous 48 states (https://www.hansenpolebuildings.com/find-a-builder/). We can assist you in getting erection labor pricing as well as introducing you to potential builders.

A CAUTION in regards to ANY erector: If an erector tells you they can begin quickly it is generally either a big red flag, or you are being price gouged. ALWAYS THOROUGHLY VET ANY CONTRACTOR https://www.hansenpolebuildings.com/2018/04/vetting-building-contractor/


DEAR POLE BARN GURU: Do your pole barns come in 48’ width?

About Hansen BuildingsWHITNEY in DANVILLE

DEAR WHITNEY: All Hansen Pole Buildings are 100% custom designed to best meet our client’s wants and needs. You may have any width, length or height you desire – down to even fractions of an inch, without having to pay a premium for some perceived standard.


Screw Penetration, Truss Carrier Requirements, and Roof Insulation

Today’s Pole Barn Guru answers reader questions about screw penetration into decking/substrate, header aka truss carrier requirements, and a proper roof insulation solution.

DEAR POLE BARN GURU: Should the screws for exposed fastener metal panel roofing COMPLETELY penetrate the 1/2″ plywood decking/substrate? STEVE in WARREN

DEAR STEVE: For through screws, they should not only completely penetrate any substrate, but also at least an inch into underlying purlins. Relying upon screws into decking only could prove to be a failure looking for a place to happen in a severe wind situation.


DEAR POLE BARN GURU: On a 14’ x20’ building with 4×6 post 8’ tall what are the requirements for the header beam or beams? Can I use two 2x10s one out and one inside? TIM in STATE ROAD

Ask The Pole Barn GuruDEAR TIM: Header beam (aka truss carrier) requirements can be determined by a Registered Professional Engineer and are based upon this formula:

(Roof live and dead loads) x (1/2 span of truss + any eave overhang in feet) x (column spacing in feet squared)

Divided by

8 x Sm (Section modulus of proposed beam) x Fb (Fiberstress in bending of proposed beam) x Cd (Duration of Load)

If resultant is less than 1, then beam is okay.

Here is an example, based upon assumption your building is in a minimal snow area, steel roofing over purlins, no or light weight ceiling) columns are every 10 feet, one foot overhangs and available lumber is 2×10 SYP #2

(20 psf + 10 psf) x (14’/2 + 1’) x 10’^2 / 8 x 21.3906 (Sm of a 2×10) x 800 x 1.15 = 0.15 <= 1

For sake of this example, a single 2×10 #2 SYP would be adequate in bending. It may not be adequate for meeting required bearing area (can be confirmed with truss manufacturer).

Beams and connections should also be verified for adequacy against uplift forces, as well as deflection.


DEAR POLE BARN GURU: I’m about to build my ‘Miracle Truss’ building which uses steel trusses with lumber purlins/girts. I have a concrete slab with 2″ Styrofoam and radiant heat to provide some warmth in the winter. I’m thinking of using foil/single bubble vapor barrier in between the roof sheeting and wood purlins. In the future I’d like to add bat insulation to the inside of the roof. For the walls I’m not sure if I should use a foil radiant film – non-permeable…or if I should instead use house wrap like ‘Tyvek’. Again, as time and $$ allows I’d like to add bat insulation and maybe OSB half way up the walls. I’d appreciate your professional opinion on how best to ‘wrap’ my building and also ‘future proof’ it in case I happen to win the lottery and can afford to fully insulate it someday. Thank you. RICK in HILLSBORO

DEAR RICK: Code will not allow you to place batt insulation between your purlins unless you have at least an inch of continuous airflow above from eave to ridge. Impossible to do given orientation of roof purlins.

I would use two inches of closed cell spray foam directly to underside of your roof steel. Later, you could fill balance of cavity between purlins with unfaced rock wool, or open cell spray foam. For your walls, use a Weather Resistant Barrier (aka house wrap) and you can add either Kraft faced batts or unfaced batts with a 6mil vapor barrier on the interior at a later date.


Skylights Leaking

Skylights Leaking

Reader DIANA writes,  ”skylights leaking in 40 year old barn. Is it possible to replace the sky lights with metal.”

Skylights in steel roofs are problematic, and not just due to them eventually leaking. You will certainly want to read this article: https://www.hansenpolebuildings.com/2016/01/one-more-reason-to-not-use-skylights-in-steel-roofs/.

Now, considering your entire roof is 40 years old – it would be possible to replace only skylight panels. This would be providing rib configuration of steel can be matched. Over 40 years many patterns have been discontinued.

You asked for my expert opinion and I therefore take upon myself to answer as if it was my very own building. This isn’t about trying to make money (although some readers may become Hansen Pole Buildings’ clients following reading of a few of my articles), it is about people getting a great value for their building dollar. I’d be first to admit to it, if I did not believe our buildings are an example of best value.

If someone actually does happen to have a better value component, let me know and we will try to incorporate it and, if possible, improve upon it.

I’d look to replacing entire roof surface. Paint systems, such as Kynar (https://www.hansenpolebuildings.com/2014/05/kynar/), are available in most U.S. areas. There are also ‘Lifetime’ warrantees available on many SMP (https://www.hansenpolebuildings.com/2014/05/smp/) painted products.

Your existing roofing was probably installed using nails, rather than screws. It was industry standard then (read more here: https://www.hansenpolebuildings.com/2011/12/ring-shank-nails/). Ideally a new roof panel screw layout will be such as with some adjustment all existing nail holes can be missed.

I’d recommend using powder coated Diaphragm screws to attach roofing to underlying purlin framing. You can read why here: https://www.hansenpolebuildings.com/2012/08/this-is-a-test-steel-strength/.

3M VHB Tape

3M™ VHB™ Tape

Reader WILLIAM in DYER writes:

“I’ve been researching pole buildings, and the weak point for putting one up seems to be the screws and washers.  Have you looked into using 3M™ VHB™ tape instead of screws and fasteners for attaching the metal exterior sheeting? What are the pros/cons of tape only? Thanks.”

Personally the only way the screws holding the steel roofing and siding on would be the weak point would be if the wrong product is being used, or the right product is being improperly installed.

Here is the scoop on VHB™ tape straight from 3M™:


  • Fast and easy-to-use permanent bonding method provides high strength and long-term durability
  • Virtually invisible fastening keeps surfaces smooth
  • Can replace mechanical fasteners (rivets, welding, screws) or liquid adhesives
  • Black, 0.045 in (1.1 mm), modified acrylic adhesive and very conformable acrylic foam core bonds to a wide variety of substrates including powder coated paints and irregular surfaces
  • Eliminate drilling, grinding, refinishing, screwing, welding and clean-up
  • Creates a permanent seal against water, moisture and more by offering better gap filling capabilities
  • Pressure sensitive adhesive bonds on contact to provide immediate handling strength
  • Allows the use of thinner, lighter weight and dissimilar materials


Dream, Design, Deliver with our 3M™ VHB™ Tape 5952. It is a black, 0.045 in (1.1 mm) modified acrylic adhesive with a very conformable, foam core. It can replace rivets, welds and screws. The fast and easy to use permanent bonding method provides high strength and long-term durability. It offers design flexibility with its viscoelasticity and powerful ability to bond to a variety of surfaces.

Convenience Meets Extreme Bonding Power 
Our 3M™ VHB™ Tape consists of a durable acrylic adhesive with viscoelastic properties. This provides an extraordinarily strong double sided foam tape that adheres to a broad range of substrates, including aluminum, stainless steel, galvanized steel, composites, plastics, acrylic, polycarbonate, ABS and painted or sealed wood and concrete. Our bonding tapes provide excellent shear strength, conformability, surface adhesion and temperature resistance. They are commonly used in applications across a variety of markets including transportation, appliance, electronics, construction, sign and display and general industrial. Reliably bonds a variety of materials with strength and speed for permanent applications. 

Dream, Design, Deliver with the 5952 Family of 3M™ VHB™ Tapes 
The 5952 family of 3M™ VHB™ Tapes utilizes modified acrylic adhesive on both sides of a very conformable, adhesive foam core. The combination of strength, conformability and adhesion makes this family one of the most capable and well-rounded 3M™ VHB™ Tapes. It is specifically designed for good adhesion to high, medium and lower surface energy plastics and paints, metals and glass. Applications for this tape include bonding and sealing polycarbonate lens over LCD, signage and windows to post-painted control panels. 

An Unconventional Foam Tape 
We invented 3M™ VHB™ Tapes in 1980 as the first of their kind. These unique tapes combine conformability with a strong, permanent bond. The result is a family of extraordinarily strong tapes that adhere to a broad range of substrates. 3M™ VHB™ Tape is a proven alternative to screws, rivets, welds and other forms of mechanical fasteners. Skyscrapers, cell phones, electronic highway signs, refrigerators, architectural windows and more all rely on this specialty bonding tape for one or more steps in the assembly, mounting, fastening and sealing process. This trusted and reliable tape offers a consistent bond, outstanding durability and excellent solvent and moisture resistance. 3M stands by all of its products and is there to provide you with design guidance and technical support when you need it. 

Proven Reliability from 3M™ VHB™ Tapes 
3M™ VHB™ Tape offers a durable bond in a way that mechanical fasteners can’t. This tape enhances the appearance of finished goods by eliminating rivets and screws while providing immediate handling strength. In most cases, fastening with 3M™ VHB™ Tape is a quicker process than drilling, fastening, or using liquid adhesive. Our versatile line of tapes can be used indoors or outdoors in a variety of applications, including window, door and sign assembly, electronics, construction and countless other industrial applications. Chemically resistant as well as UV and temperature stable, 3M™ VHB™ Tape can withstand the heat of Dubai to the cold of Canada. The unique acrylic chemistry is extremely durable and resistant to change over time, making this a long-lasting and powerful tape you can trust. 

Bringing Better Ideas to the Surface through Science and Innovation 
In our 3M Industrial Adhesives and Tapes Division, we apply the science of adhesion to deliver innovative solutions that improve the design and manufacturing processes of companies around the world. In the end, our technologies help customers like you deliver competitive products to the market faster and more efficiently. 

Mike the Pole Barn Guru comments:

Why it might not be the best choice….


In order to utilize it with the steel panels, it would need to be tested for shear strength by an independent engineer. It would preclude the use of Building Wrap (like Tyvek) in walls, as well as radiant reflective barriers or Dripstop/Condenstop in roofs.

While it sounds like an excellent product, the cost along may prove prohibitive, as the lowest price I am seeing is somewhere around 70 cents per lineal foot, making it around 10 times as expensive as the diaphragm screws we provide and even more expensive than the smaller diameter lesser quality fasteners used by most post frame suppliers and builders.


Screw Ridges or Valleys?

Screw Through Ridges or Valleys?

Today’s article is courtesy of the Journal of Light Construction online:

Q: The new corrugated metal roofing on our client’s garage leaks. The installer had driven the fasteners through the valleys and into the 2-by rafters. We’ve since been told that corrugated roofing should always be fastened through the ridges of the corrugation. Which method is correct?

A: Rob Haddock, a metal-roof consultant and director of the Metal Roof Advisory Group, responds: The culture of fastening through the ridge (crest) or through the valley of the metal-roof profile seems to vary in the continental U.S. from one place to the next, from one contractor to the next, and even from one manufacturer to the next. Many years ago (before the advent of weather-sealing washers on fasteners), corrugated roofing was always fastened through the ridges using “lead head” nails. These were galvanized roofing nails with a lead washer under the head. As a nail was driven and its head came in contact with the roofing, the soft lead was supposed to conform to the surface of the roof to provide a seal. But these fasteners were notorious for leaking, which is why they were always driven through the high points of the roofing profile.

Powder Coated ScrewToday the fasteners of choice for corrugated roofing are gasketed hex-head screws with a metal and rubber washer below the head. As the screws are driven, the washer presses against the metal roofing to form a water­proof seal. If the screws are driven correctly, fastening through either the valleys or the ridges of the roofing is considered acceptable in this country. Valid arguments can be made for both preferences. If the fasteners on your roof were all properly driven, it is unlikely that they are the source of your leaks, regardless of whether they were driven through valleys or ridges.

No matter whether your installer prefers to screw ridges or valleys, there are several factors to consider when fastening metal roofing to a building. Be sure to choose the right fastener—the right length as well as the right material—for your particular application. Roofing manufacturers often recommend certain fasteners and fastening schedules for their products according to the structural material of the roof. Each fastener must be driven straight into the metal roofing perpendicular to the plane of the roof to ensure that the washer seals evenly around the fastener hole. Also, fasteners should be driven using a properly adjusted torque-sensitive tool to avoid over-driving. Applying too much torque when fastening through the ridges could crush or distort the profile of the roofing, and applying too much torque in the valleys could distort the washer to the point where it no would longer create an effective seal.

Getting Screwed: The Powder Coated Screws Saga

Getting Screwed, a Powder Coated Screw Story

Thank you to our Guest Blogger today-from our Boss –   Eric Graff  – owner of Hansen Buildings

Hansen Buildings is very proud that we are one of very few pole building kit suppliers offering our customers powder coated screws. There is nothing more unsightly to me than a new pole building that has just completed construction and a large portion of the paint is missing from the screw heads. I know what most of you are thinking, how different can our screws be from our competitors fasteners? Extremely different actually, some competitors don’t even use screws to fasten their steel, they use nails! As someone who works daily out of another manufacturers building that has the steel siding and roofing nailed, never consider this option.

Pole building screws vary in every way possible. You will see many different paint systems, different lengths, diameters, head sizes and designs, screw designs, washers and coatings that it will make your head spin. Keep in mind that although screws are a small part of an entire structure they are one of the most important pieces in the buildings’ overall design.

This summer I happened to visit one of our clients’ buildings who also happens to be a friend. He needed a couple of wainscot panels replaced that were scratched. I brought with me the three panels I was going to replace for him and a handful of screws. While removing the existing panels I noticed some flaking off the heads of the screws. This confused me as our powder coated screws should show very little or no signs of paint coming off during installation. In fact our supplier offers a warranty against this when you use their approved lobular drive bits:


I finished replacing the panels and took the problem screws back with me.

Paint Chipping Off ScrewAs soon as I got back to our warehouse I grabbed a different color of screw and a couple different stitch screws for fastening trims to see how they fared. Unfortunately it was the same results regardless of type of screw or color. My first thought was, “where are all the customer complaints on this”? To me this was a major malfunction. I called our supplier and explained what I was seeing and sent photos to go along with our experience. They confirmed after some back and forth that there was indeed something very wrong with the paint on these particular screws.

I then thought back to a visit to the NFBA (National Frame Builders Association) Expo that we attended in St. Louis, MO in the spring of 2012. I remember visiting one booth in particular that was trying to sell us on their screws. I stood there and listened attentively with the Pole Barn Guru standing next to me who I could see was ready to ask some very pointed questions. The first question to leave his lips was, “Do you powder coat your screws”? The answer was a clear NO and a look of… “why does that even matter?”. After further discussion this supplier tried to explain to us that standard paint is just as good. When asked if all the paint will stay on after installation we were told, “Industry standard requires that a maximum of 25% of the paint can come off during installation to meet grade”. I could tell Mike The Pole Barn Guru was saying to himself, “Are you kidding me? 25% of the paint coming off new screws on our building would look hideous”. This confirmed to me why powder coated screws, when working as promised, are a much better product and worth the added cost.

Getting back to my screw situation required months of testing with the supplier before the issue was found. The cause ended up being the zinc plating on the steel below the paint that was not allowing the paint to properly adhere to the screw. We have since gone to a new plating to resolve all issues.

I learned a few things on this screw journey. Our screw supplier tests each run of screws in a laboratory controlled setting. The drills that test each screw run only at one speed, one pressure, at a perfectly straight angle by running a screw through 29g steel into a framing member. Yes I know, this is a far cry from the actual end user who uses these with a variety of drills and within many different environments.

Screw Rules:

  • Always use a drill that has a variable clutch feature so that you can adjust the level of torque before it stops driving the screw.
  • Do not over drive the screws. They should seat firmly without squishing the washer out like a muffin top.
  • Under drive the screw and you will have building leaks.
  • Keep the angle of your drill as close to perpendicular to whatever you are driving into as possible so as not to slip and cause bloody knuckles or scratches on your panels.
  • Never use a pneumatic drill.
  • You will have an easier time driving and avoiding mistakes by pre-drilling your steel.
  • Drive speed matters. The faster you drive the screw through steel the less impact it will have on the face of the screw.
  • If using our screws, purchase the lobular bits as they must be used to maintain the warranty.
  • Make sure to use the right screw in the right location. Hansen Buildings provides stitch (for installing trims only) and diaphragm screws (for installing roof and siding panels).

Stick to these rules and you are well on your way to constructing the best building possible. Screws are one of the most important parts to the complete design of your building. Hansen Buildings takes great care to provide the best possible building along with a keen eye for any product defects. We could be just another building kit supplier, but we chose long ago not to be. Every component in our building has been chosen with quality and experience in mind to provide the best value building kit on the market.