Tag Archives: glulam posts

Wouldn’t Field Laminated Posts be Stronger and Possibly More Economical?

Wouldn’t Field Laminated Posts be Stronger and Possibly More Economical?

Reader CHRIS in AIRVILLE writes:

“Wouldn’t field laminated posts be stronger and possibly more economical? I have searched your previous blogs and found some information regarding this but they all seemed to refer to the laminated posts being ordered and pre-built. I would think that it would be, easier, stronger, and produce a better product if customers where shipped a load of 2×6 or 2×8 boards that they then laminated themselves. I say this based off, by your own articles, a laminated board is stronger than a sawn post. In addition, you would most likely be able to have a straighter post in that you could oppose the crowns as you laminate the post and the resultant nail-lam would/should be almost perfectly straight. I knew somebody years ago that did this by laminating treated boards to create posts that came out of the ground about 3-4 feet and then splicing non-treated posts on top after the bottom posts were set. This was considerably easier for setting the posts because he didn’t have 20 or so feet of post to wrestle above the hole while he was trying to set and plumb them. But I believe I saw a previous blog post where you mentioned that the splices may deplete the strength significantly so this may not be a great option. Does it come down to an engineer signing off on the strength of a field laminated post? I have done a lot of work in the USAR field and we utilize a manual from the US Army Corps of Engineers for the shoring or unstable buildings. In that manual they detail the use of field laminated posts utilizing defined nail patterns to attain shoring members that can support quite heavy loads. I would imagine that by utilizing a defined nail pattern, as welling as gluing the boards together, a customer could create a post that could be rated for the design loads of these buildings. And they may even be cheaper than sawn posts?”

Probably not stronger, maybe less expensive if you discount your time to free.

Here are your challenges…..

In order to properly glue it takes a product stronger than construction adhesives.

Resorcinol waterproof glue is a great (although expensive) product. It is a high performance, two component adhesive designed to provide 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).

This glue is made from resorcinol, sometimes called resorcin, 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 workspace is properly ventilated. Those handling glue may find face masks necessary due to pungent odors (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.

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 lumber it is being used to bond! This is why a finger-jointed piece of resorcinol glued lumber, when tested to failure, will have lumber break, before finger-joint.

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

In order for glue to properly bond, surfaces being glued must be planed and glue applied within 24 hours (otherwise wood surfaces will ‘self-heal’ resulting in a poor bond).

So, how about throwing out glue and just nailing?

Assuming three pieces being nailed together, unless one is using 4-1/2″ long nails, any shorter length nail results in more length of nail shanks being placed into center ply. When laboratory tested to failure, this center member breaks first every time.

Without glue, regardless of nailing, these three boards act as independent members and are each prone to their natural desires to warp, cup and twist. While performing relatively well in strong axis bending (loads applied to narrow faces of individual plies), they are very poor in weak axis bending and may require additional bracing, especially in areas of partially or fully open walls.

Strength – commercially manufactured glu-laminated columns usually have a Fb (fiberstress in bending) value of 1900 psi. When you go visit your local lumber dealer and buy a 2×6 #2 Southern Pine, it has an Fb of 1100 psi. Cr (repetitive member factor when three or more members are in contact) of 1.15 makes your resulting Fb of a combination 1265. You would need to laminate five lumber yard 2×6 in order to have bending strength of a 3 ply 2×6 glu-lam.

Dr. Frank Woeste’s “Nail Laminated Wall Columns from Dimensional Lumber” (see TRANSACTIONS of ASAE Volume 27, Number 4, pp. 1127-1130, 1984) compared strength of nail-laminated posts, with internal non-reinforced butt end splices.

In Woeste’s testing three-ply 2×6 #2 Dense SYP nail laminated posts, were compared in strength to 6×6 #2 SYP solid sawn columns. Moment resisting ability of a wood member is calculated from Fb X CD (duration of load = 1.6 for wind) X CM ( = 0.85 wet service factor for dimensional lumber) X Cr (repetitive member factor for 3 members joined together) X Sm. As testing was done on lumber not been subjected to moisture CM will be disregarded for comparisons.

For 2×6 #2 Dense SYP (based upon 1985 values) 1450 X 1.6 X 1.15 X 3 members X 7.5625 = 60,530 in-lbs. For 6×6 #2 SYP 850 X 1.6 X 27.73 = 37,712 in-lbs. Therefore, the 3 2×6 (no splices) would be 60% stronger than the solid sawn 6×6.

In this study, using butt spliced columns, 3 2×6 #2 Dense turned out to be only 64% as strong as a 6×6!

Using results of this scientific study, it would appear non-reinforced butt spliced columns should probably be used at a value of somewhere around 40% of non-spliced column strength.

In summation – looking for a column stronger than solid sawn? Then a true glu-laminated column is probably your best design solution.

Why Not Use 6×6 or 8×8 Posts Up North?

Reader DARRELL in LUCEVILLE asked this question and included photo below.

While this photo is not of a Hansen Pole Building, I can comment upon it. Featured in this building photo are glulaminated columns – they are a great product, high strength to weight ratio, straight, highly resistant to warp and twist. They are strong because they are most generally manufactured from high strength materials, most three ply 2×6 columns have a Fb rating (Fiberstress in bending) of roughly 1900 psi. Your local lumber dealer or big box store will gladly sell you a 2×6 #2 with a Fb rating of anywhere from 1000 to 1170 (depending upon lumber species, with SYP lowest and Douglas Fir highest), so a glulam’s three members start off being about equal to five every day individual 2×6.

What about strength comparisons to solid timbers?

To determine bending strength of a member, multiply Fb X Sm (Section Modulus). A three ply 2×6 glulam would be 1900 X 19.86 = 37,738 in-lb. A 6×6 #2 SYP would be 850 X 27.73 = 23,570 in-lb. A 6×6 #2 Hem-Fir (treated species of choice in Western U.S.) has a base Fb of 575 with a reduction for incising of 20% (X .80). 575 X .80 X 27.73 = 12,755 in-lb.

Clearly, when picking for strength, glulam columns are going to be a better choice.
When it comes to practicality on a jobsite, would you prefer to carry a 20 foot long glulam weighing roughly 100 pounds, or hefting a same length 6×6 tipping your scale at 180 to 300 pounds? Not much to think about there!

Glulams columns are more prevalent in northern states due to locations where they are manufactured – primarily Pennsylvania, Ohio, Wisconsin and South Dakota. We do offer them as an option on any Hansen Pole Building. Give a call to a Building Designer today at 1(866)200-9657 for your post frame building design solution.

Dear Pole Barn Guru: What Size Glulam Should I Use?

Welcome to Ask the Pole Barn Guru – where you can ask questions about building topics, with answers posted on Mondays.  With many questions to answer, please be patient to watch for yours to come up on a future Monday segment.  If you want a quick answer, please be sure to answer with a “reply-able” email address.

Email all questions to: PoleBarnGuru@HansenPoleBuildings.com

DEAR POLE BARN GURU: I’m building a 32’x40′ pole barn using 6×6 treated posts on 8′ centers and would like to use a glue-lam beam across the 40′ length, but am not sure how to calculate the size needed to support the roof or if I need to increase the support post size.

This will be the ridge beam. I live in a sparsely populated area of Alaska, but plan on a trip to town soon to look at other similar sized buildings. There are no building regs out here, but I have looked at some large metal buildings blown down by 90 mph winds we had two years ago and another built out of rough cut spruce logs (ridge beam type) that looked pretty simple to build. I planned to use posts sunk 6′ and set in concrete. I always like to err on the safe side, so overkill is OK. MUSHING

DEAR MUSHING: Even in the remote areas of Alaska, there are probably much safer and practical methods to design a pole building rather than trying to utilize a ridge beam 40 feet long. I’d seriously recommend rethinking your design and using prefabricated ganged (two ply or greater) wood roof trusses placed at each sidewall support. This will be much more efficient than the use of a huge beam.

In any case, you need to determine the design load for your site. Here is one possible source: https://www.groundsnowbyzip.com/

The International Building Code also provides a table of ground snow loads for Alaskan locations: https://publicecodes.cyberregs.com/icod/ibc/2012/icod_ibc_2012_16_sec008.htm

You might want to consider getting an engineered pole building kit package, which could be easily shipped out of the Port of Seattle or Tacoma. This would take away your guessing at how to construct it right.

Back to your question….assuming a relatively low roof live load of 40 psf (pounds per square foot), your beam has to be able to support somewhere in the area of 30,000 pounds of weight (this will depend upon the dead loads – what is being used for roofing, etc.).

Assuming the snow will remain on the roof for an extended period of time, a Duration of Load of 1, is probably realistic. This means you will need a 2400f rated glulam with a Section Modulus of around 800 (for information on Bending Moments and Section Modulus read more at: https://www.hansenpolebuildings.com/blog/2012/09/bending-moment/).

In the above scenario, you would be looking at a 6-3/4” x 27” deep glulam beam!! Not only will this be amazingly expensive, but it will also result in the need to hire a crane to set it in place.


DEAR NICK: Thank you for your continued interest in a new Hansen Pole Building. Among the thousands of building kit packages we have provided are hundreds in New York (as well as every other state in the U.S.A.). We are VERY protective of the personal information of all of our clients, just like we will be of yours. Most people feel very uncomfortable with having “strangers” visit their homes and buildings. It is a security and safety issue, as it would be all too easy for an unscrupulous person to use this method as a way to case things out for “less than helpful” activity.  Please click on the Free Product Guide and we will be happy to mail you a very nice 32 page “showroom” of our buildings.

Here is what a few of our clients have to say: https://www.hansenpolebuildings.com/testimonials.htm

DEAR POLE BARN GURU: You have provided a tremendous amount of information and have given us a lot of questions that need answering – Thank you.

One of the major questions we have, what is code to make a living space (studio) type apartment inside one of these structures?  The second floor load being 40 psf, can this be increased for living space?

Do you have contractors that can assemble this on our site?  What kind of cost would be associated with assembly?

We are in the process of obtaining a VA construction loan with our local credit union and the above questions may be answered through that process.

I’ll take your questionnaire to our building department next Friday to get all those questions answered.

Thanks for your time and patience as we are just starting down this unfamiliar road.


DEAR WANTING:  You are very welcome, we try to assist our clients to be as educated as the want to become, so as to make certain the choices they make in the end, are the right ones.

A 40 psf second floor live load would be Code loading for a residential living space. You will need to meet the Washington State Energy Code for level of insulation in relationship to the number and area of openings (doors and windows) in the conditioned space. Whoever designs your HVAC (heating, ventilation and air conditioning) systems can assist you with the proper recommendations to meet the requirements.

While we are not contractors, we do deal with builders who may be able to assist you with your project: https://www.hansenpolebuildings.com/find-a-builder.php

Fair market value for assembly varies greatly depending upon geographical location and the costs of doing business in any particular state. In my mind, a competitive labor quote should be around 50% of the cost of the materials being installed. As it begins to creep upwards from there, I think about strapping on my old nail belt and doing the work myself.

Please do not hesitate to contact us at any time we can assist you.