# Glulams vs. Solid Sawn Columns

A Hansen Pole Buildings client recently called his Building Designer Rick. The client was concerned as three ply glulams were provided for his pole building kit package, instead of the 4×6 and 6×6 solid sawn columns which were on his plans.  He is concerned his inspector will give him trouble about this and would like an e-mail stating all is good.

Always happy to oblige Rick and help out a client, this is what I wrote:

“At no extra cost to you, your building columns have been upgraded from solid sawn columns, to glulam columns.

The strength of any member which resists bending, is primarily determined by its fiberstress in bending (known as Fb) multiplied by the section modulus (Sm) of the member.

For information on the solid sawn columns, this makes for good reading: https://www.hansenpolebuildings.com/blog/2014/08/lumber-bending/

The design specifications for the Titan Timbers provided are here: https://www.timber-technologies.com/webfiles/fnitools/documents/column_specs.pdf

With a Fb rating of 1900 psi and a Sm of 19.9, the product of the two is 37,854 in-lb. Compare this to the values of solid sawn timbers and you (or anyone who might question them) can see the huge difference in strength provided by the glulams.”

In a not too distant past life, Dale (one of the owners of Timber Technologies, which manufactures the glu-laminated Titan Timbers) and I worked together for another glu-laminated column fabricator.

Both of us learned plenty from the experience.

In my case, I learned the values of glu-laminated columns other than just the strength (in many cases a three-ply 2×6 glulam will even replace a 6×8 timber!).

They are light weight. I’ve stood 24 foot long 6×6 columns in holes before. Weighing in at well over 200 pounds – it is a task! A triple 2×6 glulam – about ½ the weight!!

Properly fabricated, a glulam columns is going to also be perfectly straight, as well as prone to resist the bane of anyone constructing a pole building – warp and twist!

All-in-all this particular Hansen Pole Building customer got what is known as, “A pretty sweet deal”.

# Poles for Pole Barns

Some days it seems there are nearly as many possible design solutions for pole barn “poles” as there are pole barns!

Here is a brief overview of the organic (think coming from trees) ones. For the sake of brevity, I will limit this article to only applications where the columns are embedded in the ground.

Old utility poles – not a good choice for many reasons:

https://www.hansenpolebuildings.com/blog/2012/11/utility-poles/

https://www.hansenpolebuildings.com/blog/2012/11/used-utility-poles/

Solid sawn pressure preservative treated dimensional lumber or timbers.

Be wary of trying to recycle old treated wood if it has been treated with an oil based preservative:

https://www.hansenpolebuildings.com/blog/2012/11/pcp/

Structural joists and planks are lumber which is two to four inches thick and five inches and wider. These would include 2×6, 2×8, etc., as well as 4×6, 4×8, etc. Structural joists and planks are graded under a more stringent set of grading rules than either “Posts and Timbers” or “Beams and Stringers”.

Beams and Stringers are five inches and thicker, rectangular with a width more than two inches greater than their thickness. These would include dimensions such as 6×10 and 6×12.

Posts and Timbers are 5×5 and larger, where the width is not more than two inches greater than the thickness. Besides 5×5, it includes 6×6, 6×8, 8×8 and similar.

So isn’t a #2 grade a #2 grade regardless of size? Well, sort of…..larger pieces of lumber are given a #2 grade, with more defects (like larger knots). Correspondingly, the strength values are not the same. Using the measure of Fb (fiberstress in bending) and arbitrarily picking Hem-Fir as a species, a #2 6×6 has a value of 575, 6×10 is 675 and a 4×6 1105!

Regardless of the dimension of the lumber or species, proper pressure preservative treating is essential:

https://www.hansenpolebuildings.com/blog/2012/10/pressure-treated-posts-2/

Putting together individual pieces.

Multiple joists and planks can be joined to form a column, either spliced or unspliced.

In an unspliced scenario, building heights are normally limited to 16 feet, as generally it is difficult, if not impossible to purchase pressure preservative treated 2×6 or 2×8 in lengths longer than 20 foot.

I’ve discussed nail-laminated columns previously:

https://www.hansenpolebuildings.com/blog/2013/08/nail-laminated-posts/

Glu-laminated columns.