Tag Archives: solid sawn lumber

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.

Some interesting glulam reading: https://www.hansenpolebuildings.com/blog/2014/04/titan-timbers/

Glulam PolesThese afford a Building Designer a plethora of structural options which cannot be achieved by the use of other alternatives. With a high strength to weight ratio, and typically being very straight – in markets where they are available, they can be a wonderful alternative, especially for taller buildings, or cases involving high wind and/or snow loads.

With so many options and alternatives, how is a consumer to know what poles are best?

My vote is for the overall design solution which best meets your individual needs for creation of space and access and egress. As long as the design is structurally sound and Code conforming, at the end of the day it does not matter what the individual pieces were used to build it.

LVL: Laminated Veneer Lumber

What is an LVL? LVLLaminated Veneer Lumber (LVL) is an industry standard in framing of new wood frame buildings. LVLs are used to replace solid wood beams and joists. They are made in a process similar to plywood, where rotary peeled wood veneers (usually pine or fir) are dried then laminated together with glue and adhesive resins under heat and high pressure. Why use LVL’s? According to APA (The Engineered Wood Association – formerly the American Plywood Association) LVL is part of a broader family of products called SCL (Structural Composite Lumber). LVL is the most widely used SCL in the family. Laminated beams offer enhanced dimensional stability, along with fewer imperfections and stronger engineering properties than standard lumber. Standard widths (thicknesses) are 1 ¾ inches and 3 ½ inches. Lengths are available up to 60 feet. Standard depths are 9 ¼. 9 ½, 11 ¼. 11 7/8. 14. 16 and 18 inches. How strong is an LVL?  Laminated Veneer Lumber creates structural elements which virtually never fail if used correctly. Its load capacities are precisely calculated for each use. LVL grains all run in the same direction which makes it very stiff and stable. Due to its high tensile strength it has the ability to support a great deal of weight along its length without sagging. This strength also gives the ability to span long distances without the need for posts. LVLs have high design values not only for bending, but also stiffness and shear strength. Where are LVL’s most used?  In framing buildings, LVL is most often used for beams and joists. Its strength makes it good for door and window headers, stair stringers and other beams. Designed for structural applications, the surface finish is of low architectural quality. In heavier construction, they are used for support conditions requiring a high-strength lightweight member. Many companies offer engineered wood  products, each with its own specific engineering properties. Does an LVL shrink or warp?  As a low moisture content, factory produced product, LVLs resist shrinkage, warping, splitting and checking. Many manufacturers use sealants on their LVLs to protect from moisture damage. No special fasteners are required for assembly, LVLs installs just as easily as ordinary lumber. LVLs have no defects to cut out, reducing jobsite waste from downfall. How about saving trees?  Green concerned? As LVLs use veneer rather than whole sawn timber, many trees are saved. LVL production uses wood resources efficiently as the veneers come from trees with wood otherwise considered low in quality.