McArthurs Guide To Fence Post
Make a wise investment
When constructing a fencing project whether on a farm, residential property, or through
contract work, it is important to consider the quality of product in which you invest money
and time. The following is a guide of questions, answers and definitions written for fencing
buyers who need to be pointed in the right direction, or who need a little assurance that the
purchase they make will result in years of strong, reliable fencing.
Buy posts that meet or exceed
AWPA standards and SAVE.
What is “AWPA”?
The quality of your fence posts begins and ends with AWPA.
The American Wood Protection Association or AWPA, was founded in 1904 to create and maintain safe usage standards for wood products. AWPA standards are developed by technical committees in an open, consensus-based process involving individuals from many aspects of wood preservation. These guidelines are universally specified for wood preservation in the USA and are recognized worldwide. Reputable companies adopt these standards to ensure customers receive the highest-quality and best performance possible from a product. The AWPA Book of Standards is an in-depth manual of over 600 pages that covers topics from safety procedures to chemical breakdowns of preservatives. Many companies fail to follow, or do not attempt to follow, AWPA guidelines due to the rigorous and high standards of operation required. The AWPA is here to set and uphold high product standards and give customers the best possible value. For more information, visit www.awpa.com
Do the posts meet or exceed AWPA standards?
This needs to be your first question. It is the most important question.
If AWPA guidelines are not followed, choose a company that follows AWPA; companies that
do not follow AWPA guidelines cannot produce high-quality, long-lasting wood products.
Where did this wood come from?
Many companies do not know where, or how its loggers harvest wood. Only a fresh cut tree
can be properly preserved and protected in pressure treatment.
Fallen timbers that are picked from the ground have already started to decay. Using decaying
wood means buying a decaying fence post. Pressure treating does not cure current
decay, it prevents future decay. AWPA standards dictate that all wood must be free from
defects before treatment.
How long were the posts dried before treatment?
According to the AWPA, posts must be air-dried between 2 and 5 months before pressure
treatment. Kiln drying can accelerate this process, but adds significant costs. The posts
should be kept in an open yard to allow proper air circulation; stacked and spaced according to AWPA standards. Air drying is the most cost-effective way to dry wood.
Were posts tested by a moisture meter prior to treatment?
Testing wood post moisture levels with a special instrument known as a moisture meter is vital to the
pressure treatment process. Wood should have a maximum moisture level of 30 percent before pressure
treatment.
If treated while wet at a moisture level above 30 percent, preservatives used in the pressure treatment process become diluted and will only stain the outside of a post instead of soaking into the wood. While a post treated wet might look protected at first glance, any crack the post incurs will be an open invitation for environmental moisture, leading to fungal decay and insect infestations.
In other words; if the post is treated while wet, just like a soaked sponge, it will not be able
to absorb more liquid.
What is the “penetration level” of preservatives?
Penetration refers to the depth at which preservatives extend into the wood. When it comes
to penetration levels, companies should fall back on AWPA’s “2 inches or 85 percent rule.”
This means if 2 inches of sapwood is available, 2 inches should be penetrated with preservatives.
If 2 inches of sapwood does not exist, then 85 percent of existing sapwood should be penetrated with preservatives.
If this rule is not followed during pressure treatment the resulting posts will not perform properly.
What preservatives are used during pressure treatment?
The heavy metal chemical compound CCA is the predominant preservative chemical used to pressure treat farm fence posts in the Midwest.
Why are heavy metals used to preserve a post?
Because nothing eats metal, including insects! Other common preservatives used include CA-C, ACQ, and Creosote; specifics on these preservatives can be found in the AWPA Book of Standards.
From what species of tree is the post made?
The best posts are made from DENSE Southern Yellow Pines, the wood with the highest strength and longevity. These high-density pines are tougher and thicker than other pine species, resulting in overall longer lifespans. Low-density Southern Yellow Pines out of Texas, while still usable, are weaker. These low-density pine incur cracking more easily due to softness and thinness of the wood structure.
The weakest pine species with the shortest lifespans when used in outdoor wood products are Red Pines and Lodge Pole Pines, rendering them less desirable than low-density Southern Yellow Pines.
Ask About The Treating Process When You Buy Your Fence Posts.
Here Is Way Too Much Information On Ours:
Pressure Treatment Process
This process (when done according to AWPA guidelines) is what keeps fence posts standing through mother nature’s worst! Pressure treatment is a process that infuses preservative chemicals with wood to protect it from environmental decay, fungus and insects.
After wood is properly stripped of bark, it is bundled and placed in a large cylinder. Here, vacuum opens the cell structure of the wood and 150 pounds of pressure is applied to move chemical preservatives deep into posts. This creates a high enough preservative strength
to protect the posts’ heart wood. For a better explanation, and to see this process in action visit our facebook page www.facebook.com/Mcarthurpost.
Retention Levels
Retention is the amount of preservative that remains in wood after the pressure treatment process is complete. It is expressed as “PCF” or pounds of preservative per cubic foot of wood. Retention rates also determine if wood can be classified as suitable for “ground contact,” which requires a .4 PCF. A post needs to be at a .4 PCF level to be used effectively without quickly incurring rot and decay. Wood products meant for “above ground use” like fence boards, for example, only need .25 PCF, while boards used for freshwater docks require .80 PCF. Unfortunately for customers, many chain stores are oblivious to where the wood used in their posts came from and may not be willing to research the woods’ origin. Because of this, many chain stores carry posts that are not at suitable PCF levels, but are more or less stained as opposed to being treated at adequate levels.
Quality Control
This is a company’s ability to control the quality of a product from start to finish. AWPA standards were created to establish quality control in the wood product industry. The only way to establish the quality of a wood post is to core it like an apple. Then after coring, a radio isotope device is used to take x-rays of the wood. This process is done to determine if preservative levels in the sapwood of a post meet AWPA standards. From choosing how trees are harvested initially, to proper conditioning/treatment and providing a warranty, the business that customers choose should practice superb quality control!
Sapwood
Sapwood naturally surrounds heartwood. It acts as a ribcage, or the armor of the heart. It is the area of wood preservatives are infused into during pressure treatment. It is of utmost importance that sapwood is pressure treated correctly according to AWPA standards in order to protect the underlying heartwood, which is naturally untreatable. Proper treatment of sapwood prevents environmental decay of a post.
Heartwood
This refers to the naturally untreatable sturdy center of a tree. This is what the pressure treatment process protects, the heart of a post. Pressure treating is all about penetrating wood deep enough so preservatives can surround the heartwood, to protect it from insects,
moisture and decay.
Cylinder Post
This style of post is cut in a uniform way to assure it is the same diameter from top to bottom. Due to being cut in a cylindrical shape, this type of post cracks more easily than a tapered post, and typically is not under warranty because of the stressful manufacturing process. They are also typically weaker than a tapered post.
Tapered (traditional) Post
The tapered-style post naturally varies in diameter from top to bottom by one inch every 8-10 feet. This post sets more suitably in the ground than a cylinder style post, it is stronger, and longer-lasting.
Fencing Types
Board Fence:
A traditional style of wood fencing that has been used on farms for generations. Constructed of wooden rails typically 1”x6”x16” attached to wood posts. This type of fence can also have electric fencing attached behind it to keep horses from chewing on the wood.
Split Rail:
Commonly used both as a livestock fence and decorative landscape fence. This type of fence can be assembled and disassembled quite easily and has a “stacked” appearance. Fence rails are inserted and set in holes through fence posts. The rails are paddle-shaped on each end to easily slide through and sit firmly.
Diamond Rail & Rustic Rail
Similar to the split-rail fencing; rails are inserted into holes drilled in posts.
This type of rail is made from a square post that is turned on its edge and paddles are cut on both ends.
Diamond rails are squared compared to
Rustic Rails which are more curved rails.
High-Tinsile Wire:
Commonly known as “smooth wire,” this wire is installed in single/multiple strands. This type of fence is the cheapest option for wire farm fencing. It is easy to install and can have electric added to prevent livestock from leaning and pushing on the wire.
High-Tensile Field Fence:
Woven wire constructed of high-tensile galvanized metal. This wire is cheap, light and easy to work with. It has a higher-break strength than traditional low-carbon field fence.
Low-Carbon Field Fence:
Traditional woven-wire fencing that is much heavier and harder to work
with than high-tensile field fence. Even though this wire is heavier than
high-tensile field fence (9 or 11 gauge) it has a lower break strength.
No-Climb Wire:
Woven wire fencing constructed with 2”x4” squares. This type of fencing is ideal for horses; it prevents them from getting their hooves caught in the wire.
Wire Fencing
Class 1:
This class of wire fencing will usually rust in 5-8 years. It is commonly sold in chain stores. Most reputable fence installers will not use this wire.
Class 3:
Roughly 2.5 to 3 times the galvanization of Class 1 wire. This wire is expected to begin rusting in 25+ years.
Bezinal:
A coating made from 95% zinc and 5% aluminum alloy. Bezinal has roughly 1.5 to 2 times the longevity of Class 3 wire, making Bezinal a strong choice.
Bezinal & Paint:
This coating is Bezinal (described above) with a layer of paint added. This is the longest-lasting wire fence customers can purchase, having double the life expectancy of Class 3 wire.
Common fence installation products and tools:
Brace Pins :
Holes are drilled into the vertical posts and metal brace pins are inserted through
the holes to help hold horizontal posts in place. These pins also help reinforce the
posts’ positions, and should be made of galvanized metal for longevity.
Strainers:
Despite the deceiving name, this small tool is simply used to tighten wire fencing
strung between posts.
Ring Insulators
Ring insulators are used to secure wire on wood fence posts firmly so it is not easily
pulled from the post.
Tube Insulator:
Often made of rubber or plastic covering a metal insulator. Used to hold wire on
fence posts, most commonly used on electric fencing and corral panels.
Crimp Sleeves:
Despite the deceiving name, this small tool is simply used to tighten wire fencing strung between posts.
Tension Spring:
This wire spring is used to indicate the amount of tension in electric or galvanized wire fences. It also acts as a shock absorber; helping to absorb any expansion or contraction of the fence.
Spinning Jenny:
Allows galvanized high-tensile wire to be wrapped around a spool and re-rolled
for easy storage, then rolled out for easy installation.
Post Pounder:
Also called a post-driver it is used to drive fence posts into the ground. It can be manual having two handles on either side of enclosed steel, or automatic and run using fuel and a grip mechanism.
Fence Stapler:
Used to secure wire fencing onto wood posts. It resembles a nail gun and is a hand held device that deeply implants metal staples into posts. It is used to speed up labor time installing fences and make fence installation safer.