# Pressure Treated Wood



## kilitact (Jan 5, 2010)

JD wrote;



> The problem I have is that the PT lumber which is acceptable for embeddment is not approved for 'above-grade' applications, generally considered 18" or more above grade. Unless you have a very low deck, this could prove to be problematic.


JD,  from my pole building days, we used pt with a .2 retention, embedded, upward of 20 ft above ground. can you explain your statement?  :?


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## globe trekker (Jan 5, 2010)

Re: deck ledger connection

John,

I too am seeking clarification on your opinion regarding the PT wood.   Is the PT wood

the " for damp locations ONLY " type,  or is it the " for wet locations ONLY " type?

.


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## JBI (Jan 5, 2010)

Re: deck ledger connection

globe - That's my point. There are different classifications for PT lumber. The stuff you can bury isn't supposed to be used above grade, the stuff approved for above grade only can't be embedded. I'm looking at three different tags sitting on my desk right now that all say 'Above Ground Use Only'.

Kil - The better pole buildings have triple 2x for the posts, the embedded parts are higher pcf for embedment, the upper portion is either untreated or above-grade treated material. The splices are offset to provide the needed strength in the members. I'm seeing very few 6x6 or 8x8 long PT posts any more.

The higher the pcf rating the more damaged the wood fiber. The more damaged the wood fiber the greater the need for moisture to keep the wood sound. That's why the 'Ground Contact' stuff is to be used in contact with or very close proximity to the ground, to retain moisture.


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## Pcinspector1 (Jan 5, 2010)

Re: deck ledger connection

JD,

I agree some products like Borate cannot be used outside but here in the mid-west they have been using .40 ACQ for several years since big brother took away CCA. When CCA was taken off the shelf the only ones allowed to use it was the State for ground contact road signs, maybe until the States post supply ran out, not sure they still use it? What do those tags say, .25? :?:


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## JBI (Jan 5, 2010)

Re: deck ledger connection

Pc - They're all 'MCA' with varying amounts of chemicals per cubic foot. Basically, the lower the number the farther above ground it needs to be. MCA 0.06 pcf is for 'Decking Only', the other two don't specify pcf, but refer to ESRs (ESR-2067 on one and ESR-1851 for the other). The 'Decking Only' tag refers to ESR-2325.

The particular lumber manufacturer is Culpeper, and their website has some interesting information on the chemicals they use... one is the same active ingredient that is in 'Advantix' - the tick prevention stuff for your dog or cat.

I kind of thought this was all pretty much common knowledge at this point (at least for Code Officials).

If John Q. Public took the time to know his (built) environment none of this would be a problem. It was the arsenic that caused the majority of the problems. Had owners/installers/specifyers ensured that the exposed surface was sealed, kids would not have gotten sick from exposure to the arsenic.

Had any of them actually READ the warranty and product specifications, they never would have used the stuff in above grade applications that led to premature deterioration due to dehydration of the wood.

Quick sidebar: My Mother-in-Law had a pool deck built around her above ground pool for the grandkids. Kids jump in the pool, get out on the deck and jump back in. All day long, 2, 3, 4, 5 at a time. The water doesn't look right. She takes a sample to the pool store. High in copper they say, use this. Copper? Her whole house is plumbed in CPVC.

Then it dawned on me. The lumber is treated with COPPER based arsenic (hence the green hue... DOH). Seal the deck and no more high copper levels in the water (and no more arsenic either!)


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## JBI (Jan 5, 2010)

Re: deck ledger connection

Almost forgot, CCA .60 was actually what you needed for full embeddment. CCA .40 was 'ground contact', not burial.


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## kilitact (Jan 5, 2010)

Re: deck ledger connection

JD wrote:



> The better pole buildings have triple 2x for the posts, the embedded parts are higher pcf for embedment, the upper portion is either untreated or above-grade treated material. The splices are offset to provide the needed strength in the members. I'm seeing very few 6x6 or 8x8 long PT posts any more.


I've not seen any triple 2x, even with new goverment speced pole buildings, it's all 6x6, 6x8 or 8x8's.  :?

I guess UC4B would be the correct one, .2 does date me.  :lol:


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## JBI (Jan 5, 2010)

Re: deck ledger connection

Kil - Does .2 have a sister? I could use a date!  :lol: Actually Morton Buildings and at least one other major Pole Building company has switched over to laminated 2x poles. (fingerjointed no less! No butt end connections.)

First time I saw them I did a double take. I'm actually surprised it took so long for someone to come up with it.

Another advantage BTW is that the pressure treatment really only penetrates +/- 3/4 inch into the material. Using 6x6, 6x8 & 8x8 posts means the center of the poles are untreated. Any end cuts need to be field treated per manufacturers specs (please tell me you knew THAT part... :roll: ). With the laminated 2x you get more treated wood where you need it.


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## globe trekker (Jan 5, 2010)

Re: deck ledger connection

John & others,

Here is an archived article from the same source that ' cda ' listed.   This is on the types of

preservatives used in the treating of wood products.

http://www.deckmagazine.com/pdf/2008/0809/0809pres.pdf



.


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## Daddy-0- (Jan 5, 2010)

Re: deck ledger connection

You can still get the CCA from some suppliers for agricultural uses (fence posts). FYI they do make an ACQ product that is approved for direct bury but it is a special order from almost all lumber yards. The LOWES/HD's of the world really should do a better job of informing the customer about their products and approved uses. I am curious how the new lumber/fasteners etc. will hold up long term.


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## JBI (Jan 5, 2010)

Re: deck ledger connection

D-O - Every manufacturer tells you what type of fasteners are acceptable for their particular formulation. When in doubt, stainless steel works with everything. When the newer formulii came out the manufacturers did a much better job of informing people what fasteners would be required.

globe - Awesome article. Read the first three pages, will go back for the rest later/tomorrow. It's past my bedtime (YAAAAAWN). G'night.


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## kilitact (Jan 6, 2010)

Re: deck ledger connection

JD wrote:



> Kil - Does .2 have a sister? I could use a date!





> Any end cuts need to be field treated per manufacturers specs (please tell me you knew THAT part...  ).


Depends on where you stick it. I would recommend protection.   :!:  :roll:  :roll:


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## barlovian (Jan 6, 2010)

Re: deck ledger connection

John--

It is a new concept to me that lumber with higher retention levels should not be installed above grade.  I am always intersted in learning new information.

Do you think that perhaps the treated lumber that is typically used in northeast states does not have this restriction?  We see pressure-treated southern yellow pine.  It is not incised lumber.


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## JBI (Jan 6, 2010)

Re: deck ledger connection

barlovian - Last time I checked, New York was a northeast state.   

Remember, the process of pressure treating wood destroys the cellular structure of the surface, removes natural moisture and replaces it with chemicals.

The problem can be resolved by properly sealing the material against further moisture loss. Decreased moisture levels in (old) PT lumber results in worse levels of checking, splitting, bowing, twisting, etc. than you would see in untreated lumber. It also results in premature deterioration of the wood once the un- or under-treated core of the member is subjected to the elements and all that comes with it (water/ice damage, bacterial and insect damage).

The best suggestion I can make is to read the manufacturers information for every kind/type of treated lumber you encounter. The article above is good, but getting complete information direct from the source is invaluable in this line of work.


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## Mule (Jan 21, 2010)

Re: deck ledger connection

Thought this might help!


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## JBI (Jan 21, 2010)

Re: deck ledger connection

Mule - Good post. Thanks. The marking you want to the most is the AWPA Standard mark. With that you can then go to the AWPA Standard for the appropriate uses for the lumber in question.


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