Pressure treated wood ratings (pole barns)
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IHDiesel73L
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More pressure treated wood wisdom:
3) A deck built with pressure treated wood will last a long time.
Promotional literature promises lifelong performance for pressure treated wood. The Forest Products Laboratory and other research groups have shown that treated wood stakes placed in the ground for more than 40 years remain rot-free. But young pressure-treated decks, many less than 10 years old, are being shoveled into landfills. A recent technical report in the Forest Products Journal (November-December 1998) indicated that the average pressure-treated deck only lasts 9 years. Why? As the old song says, çš„tç—´ not the meat, its the motion.
Pressure treating does make wood rot resistant. But it doesn稚 make wood water resistant. Pressure treated wood still soaks and looses moisture. And as a result, the wood moves, cracks, twists, bends, cups and virtually tears itself apart. There is hope.
You can enjoy pressure treated decks for a very long time. All it takes is a little extra care during installation and a yearly dose of maintenance. Keep the wood stable by applying a coat of water repellent treatment onto all surfaces before installation. Securely fasten the deck boards with long corrosion-resistant screws. Brush-treat raw wood that is exposed when cutting and drilling. Retreat the tops of the boards with a good brushing of water repellent every year. The water repellent will keep the boards looking bright and will minimize the uptake of water. As a result the boards will have fewer cracks, splits, cups and twists.
Better yet, buy treated wood that has water repellent chemicals included as part of the pressure-treating process. UltraWood by CSI, Charlotte, NC and Wolmanized Extra by Hickson Corp., Smyrna, GA are 2 examples of this product. The repellent gets injected deep into the wood along with the preservative. This type of decking will perform better for a longer period of time. UltraWood guarantees water repellency for 50 years! I知 a skeptic, but that is quite a promise. It is a great idea to purchase KDAT lumber (kiln dried after treatment) whenever the budget allows. You will have less initial shrinkage and the deck will look much nicer for years. These recommendations are good for all wood decks, but pressure treated southern pine seems particularly sensitive.
5) Dry rot.
There really is no such thing as dry rot. Wood needs 4 things to decay: water, oxygen, food (wood) and favorable temperature (40F 105F). Wood can be too wet to decay. Waterlogged wood will not allow oxygen in to support the growth of fungi. Marine pilings kept fully submerged may never rot. And wood can be too dry to decay. Keep wood below 22% MC and you are generally safe. But the fact remains: wood needs water to rot.
Carpenters replacing a sill or corner post in an old house often find a brown, crumbly rot they call dry rot. It may be dry when it痴 discovered, but don稚 be fooled. There was or is a moisture problem that needs fixing. Most likely there is intermittent wetting. A source of moisture is to blame. Inspect carefully for signs of leakage, dampness or chronic condensation. There are a few strains of fungi that have water-conducting strands that carry water from soil into building elements. But these forms are quite rare.
10) Pressure treated lumber is resistant to attack by termites and carpenter ants.
This assumption is half true. Entomological studies have shown that arsenical treatments like the CCA commonly used in pressure treated lumber does repel and can kill termites. Termites that eat treated lumber will die. However, termites may also decide to tube around CCA treated wood and survive to enjoy the more delicate studs and joists that lay beyond the poisoned barrier. Arsenical treatments do not repel or kill carpenter ants.
Ants are attracted to wet and decayed wood because it is soft and weak. It is easy to chew. Thats why ants like foam insulation. Ants dont ingest wood, they simply hollow out wood and nest in it. CCA is fixed tightly to wood fiber, so it is not accessible to ants. Wood that is treated with borates is a different story. Borates are very soluble and can be picked up by ants as work their way through borate-treated wood. The borates are ingested when ants groom themselves. They are poisoned at this point. The characteristics of borates and CCA are significant in other ways. Since CCA is held tightly by wood fiber, it provides very permanent protection from rot in moist environments. Borates will leach out of wood that is in contact with wet surfaces leaving wood unprotected in time.
Taken from:
UMass Amherst: Building and Construction Technology » Wood Myths: Facts and Fictions About Wood
3) A deck built with pressure treated wood will last a long time.
Promotional literature promises lifelong performance for pressure treated wood. The Forest Products Laboratory and other research groups have shown that treated wood stakes placed in the ground for more than 40 years remain rot-free. But young pressure-treated decks, many less than 10 years old, are being shoveled into landfills. A recent technical report in the Forest Products Journal (November-December 1998) indicated that the average pressure-treated deck only lasts 9 years. Why? As the old song says, çš„tç—´ not the meat, its the motion.
Pressure treating does make wood rot resistant. But it doesn稚 make wood water resistant. Pressure treated wood still soaks and looses moisture. And as a result, the wood moves, cracks, twists, bends, cups and virtually tears itself apart. There is hope.
You can enjoy pressure treated decks for a very long time. All it takes is a little extra care during installation and a yearly dose of maintenance. Keep the wood stable by applying a coat of water repellent treatment onto all surfaces before installation. Securely fasten the deck boards with long corrosion-resistant screws. Brush-treat raw wood that is exposed when cutting and drilling. Retreat the tops of the boards with a good brushing of water repellent every year. The water repellent will keep the boards looking bright and will minimize the uptake of water. As a result the boards will have fewer cracks, splits, cups and twists.
Better yet, buy treated wood that has water repellent chemicals included as part of the pressure-treating process. UltraWood by CSI, Charlotte, NC and Wolmanized Extra by Hickson Corp., Smyrna, GA are 2 examples of this product. The repellent gets injected deep into the wood along with the preservative. This type of decking will perform better for a longer period of time. UltraWood guarantees water repellency for 50 years! I知 a skeptic, but that is quite a promise. It is a great idea to purchase KDAT lumber (kiln dried after treatment) whenever the budget allows. You will have less initial shrinkage and the deck will look much nicer for years. These recommendations are good for all wood decks, but pressure treated southern pine seems particularly sensitive.
5) Dry rot.
There really is no such thing as dry rot. Wood needs 4 things to decay: water, oxygen, food (wood) and favorable temperature (40F 105F). Wood can be too wet to decay. Waterlogged wood will not allow oxygen in to support the growth of fungi. Marine pilings kept fully submerged may never rot. And wood can be too dry to decay. Keep wood below 22% MC and you are generally safe. But the fact remains: wood needs water to rot.
Carpenters replacing a sill or corner post in an old house often find a brown, crumbly rot they call dry rot. It may be dry when it痴 discovered, but don稚 be fooled. There was or is a moisture problem that needs fixing. Most likely there is intermittent wetting. A source of moisture is to blame. Inspect carefully for signs of leakage, dampness or chronic condensation. There are a few strains of fungi that have water-conducting strands that carry water from soil into building elements. But these forms are quite rare.
10) Pressure treated lumber is resistant to attack by termites and carpenter ants.
This assumption is half true. Entomological studies have shown that arsenical treatments like the CCA commonly used in pressure treated lumber does repel and can kill termites. Termites that eat treated lumber will die. However, termites may also decide to tube around CCA treated wood and survive to enjoy the more delicate studs and joists that lay beyond the poisoned barrier. Arsenical treatments do not repel or kill carpenter ants.
Ants are attracted to wet and decayed wood because it is soft and weak. It is easy to chew. Thats why ants like foam insulation. Ants dont ingest wood, they simply hollow out wood and nest in it. CCA is fixed tightly to wood fiber, so it is not accessible to ants. Wood that is treated with borates is a different story. Borates are very soluble and can be picked up by ants as work their way through borate-treated wood. The borates are ingested when ants groom themselves. They are poisoned at this point. The characteristics of borates and CCA are significant in other ways. Since CCA is held tightly by wood fiber, it provides very permanent protection from rot in moist environments. Borates will leach out of wood that is in contact with wet surfaces leaving wood unprotected in time.
Taken from:
UMass Amherst: Building and Construction Technology » Wood Myths: Facts and Fictions About Wood
EddieWalker
Epic Contributor
My experience is that water proofing and sealers are more for looks then structural integrity. In every case that I've seen a deck fail, it's from poor design, improper fasteners and under sizing spans. While newer treatment methods and fast growing trees tend to twist and warp more so then they used to, if they are screwed and bolted together properly, there is very little movement of the wood. If the structure is strong enough not to move, it will not come apart and it will last for decades.
Most common mistake is from using nails. They just don't hold outdoor structures together for very long.
Next, spreading the floor joists out to 24 inches or more means the decking bounces and everything comes loose. Then there is a big lack of knowledge about diagonal bracing and sheer strength. Posts more then a foot above the ground are going to move on you if they are not locked into position. The longer the post is above grade, the more it needs to be braced and locked into position.
Then they don't use brackets, bolts and notches to carry the load.
Post failure is always from standing water. Some might twist and turn because they are not held into position very well, but if dry, they never rot. If a post is rated for ground contact, it will last for decades and decades if it stays dry. I've pulled fence posts out that where fifty years old that looked brand new below grade. Ugly above ground, but still sound top to bottom. I've also pulled posts that where less then ten years old that where rotten all the way through at ground level that looked perfect above and below grade. The rotted because water pooled at the base. Most of them had concrete in the hole that was a few inches below grade, and water just sat in that low area.
Some people are going to want the very best, but for building a barn or a deck, nothing is going to be more cost effective then a treated 6x6 from any of the lumber yards out there. Instead of focusing on more expensive materials, it's always better to focus on how to build it better.
Eddie
Most common mistake is from using nails. They just don't hold outdoor structures together for very long.
Next, spreading the floor joists out to 24 inches or more means the decking bounces and everything comes loose. Then there is a big lack of knowledge about diagonal bracing and sheer strength. Posts more then a foot above the ground are going to move on you if they are not locked into position. The longer the post is above grade, the more it needs to be braced and locked into position.
Then they don't use brackets, bolts and notches to carry the load.
Post failure is always from standing water. Some might twist and turn because they are not held into position very well, but if dry, they never rot. If a post is rated for ground contact, it will last for decades and decades if it stays dry. I've pulled fence posts out that where fifty years old that looked brand new below grade. Ugly above ground, but still sound top to bottom. I've also pulled posts that where less then ten years old that where rotten all the way through at ground level that looked perfect above and below grade. The rotted because water pooled at the base. Most of them had concrete in the hole that was a few inches below grade, and water just sat in that low area.
Some people are going to want the very best, but for building a barn or a deck, nothing is going to be more cost effective then a treated 6x6 from any of the lumber yards out there. Instead of focusing on more expensive materials, it's always better to focus on how to build it better.
Eddie
MacLawn
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That how to build better - that's the ticket boys.
anotherbri
New member
I know this thread is old, but I came across it while trying to figure out if there was a better treated wood pole these days for sinking into the ground. The 2nd picture here is definitely the better wood because it is .40 ACQ type UC4A which would even be better than CA-C .31 UC4B. My question.....is ACQ treated lumber still available?? I'm a little reluctant to use the UC4A "ground contact" poles from the big box stores to sink into the ground to hold up a structure. They are only .15 PCF Ca-C treated. If CA-C treated lumber is the only thing available these days, I would rather use UC4B @ .31 PCF.
Sawyer Rob
Super Member
Around here we can get .40 or .60... .60 is for in ground use and all the .60 post I've put in the ground are holding up just fine...
.40, not so much..
SR
.40, not so much..
SR
bandaidmd
Platinum Member
Morton laminates there 6x6 out of 3- 2x6's claiming a 2x6 gets full penetration of the preservative where a 6x6 will have an untreated core. theres also a company the makes a sleeve to set the post into.
Sawyer Rob
Super Member
Morton isn't the only one to do that... It's a quite common build practice today...
Mostly it's done to get straighter more stable post though...
SR
Mostly it's done to get straighter more stable post though...
SR