So, now I find out that most locally available ACQ lumber is only treated to a .25 saturation rate. Checked several sources – same thing. The only exceptions being 4×4, 6×6, etc posts. No framing lumber, etc, is available in .40. I talked to a local wood treater and he told me that “they” are all doing it to control costs since the new ACQ chemicals are more expensive, and that the .40 CCA treating was overkill.
Well, ok, that’s one story, and granted from an expert. Here is my opinion: Back when we used to build decks, etc from .25, they would fail a lot faster. For about the past 8 to 10 years mostly only .40 CCA was available and things were holding up much better…
Personally, I’d rather pay the higher prices for a quality product, build with the confidence of knowing that I would have fewer callbacks and happier customers for the long run, and pass the extra cost on to the customer.
BTW – just as a side note, here in NC, all PT lumber is SYP (Southern Yellow Pine). I know that on the west coast, etc, they use other woods. Not sure how that might effect this situation.
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Did your read the recent article about the varying levels in different framing applications? This was done to keep overall costs down. sleepers and posts have the highest percentage because of exposure, but deck boards get the minimum due to lower risk.
...that's not a mistake, it's rustic
Where was the article?ThanksMatt
Interesting. I just bought a pile of ACQ at the local HD. The 2x8's were 0.1 "above ground use"; the 4x4's, etc., were 0.25; and the 3/4 plywood was 0.44. Sounds like there's no consistency on the levels.
bd: do me a little favor and check your numbers - they don't sound right. Maybe it has to do with your locale - what area do you live in.Matt
> here in NC, all PT lumber is SYP (Southern Yellow Pine). I know that on the west coast, etc, they use other woods.
Back in the CCA days, the big difference was that SYP would soak up the chemicals very deep into the wood, all the way thru two by. But our Doug fir out here, even with the incising machine, wouldn't let it soak in more than about 1/16". Don't know if ACQ is the same. That's kind of a pain because it leaves cut ends and accidental gouges unprotected. The remedy is to paint them with Jasco's Termin-8, a copper napthenate solution.
I have a "temporary" walk where doug fir painted with Termin-8 has been in contact with the ground for over 20 years, and is still doing fine. For something that didn't require inspection, I'd be inclined to skip the ACQ and soak Termin-8 into ordinary Doug fir.
-- J.S.
Perhaps ACQ, being a different chemical composition, just needs less in order to provide the equivalent level of protection, in comparision to CCA?
Data. We want data.
Is FHB listening?
You would hope so, but the guy at the local wood treaters said it was purely a cost savings thing, and admittedly the ACQ is only marginally more expensive than the CCA.
I just think this ACQ stuff has potential for a bad situation down the road. Like back in the 70s when the local fire codes were I lived required fire resistant plywood to be used on townhouse roofs (row houses), and then 15 years later they find out that the chemicals caused the wood to severely deteriorate. To me, ACQ is an unknown - a roll of the dice.
Matt
Here's a good but dry article about the subject at hand. I recommend skipping to the final page to read the author's conclusions.
R
That article will give you your full quota of academic speak in a hurry... What I got from the conclusion was that, in the formulations used, above some point more was not necessarily better, and that the results were inconsistent.
I skimmed, but did not fully read, the article and I am not sure just what preservative system the author was referring to as "acid copper". The primary preservative that has been discussed as the primary replacement for ACC is ACQ. I did not see anything on the list of treatments that I recognized as ACQ, which is Alkaline Copper Quat.
The standard industry recommendations for treatment levels appear to be the same as those used for CCA for the same applications:
http://www.sutherlands.com/acq.htm
http://www.taunton.com/finehomebuilding/pages/h00127.aspbobl Volo, non valeo
Basically, your take on the conclusion is equal to my own, but having read a good deal of the report, it occurs to me that the evidence leading to the conclusions allows a little expansion for discussion. In general, it seems to suggest that the thickness or penetration depth of a minimum standard of the heavy metal compound barriers was secondary to proper handling within specific environments.
For example, from the evidence, one could infer that a person might use a stick of lumber with .4 preservative retention as horizontal decking to provide a belt and suspenders for durability to his project, but it’s like using a W36 header for 2-0 door. There’s a point of diminishing returns, and if at any point the deck installer simply cuts his decking and doesn’t treat the end grain to the minimum protective standard for the application, he throws away the belt and suspenders anyway. I gather that’s why the author of the article included field-applied preservatives in his review—as a measure of practicality.
So, yes—I guess it makes sense that the results were inconsistent. The stakes were all treated differently in the tank and in the field, but it’s safe to say that the article speaks directly to what started the discussion; there are different retention standards for different uses in the field. It’s fine to use .1 retention for horizontal decking above ground, but if you’re in a ground-contact context, the minimum .4 retention stock should be used. The retention standards have been tested, and again in summary, I think what the industry is saying is that you don’t need an ocean to drown a rat, a five gallon bucket will do, as long as you handle the varmint properly.
One last point—the compounds tested. Although ACQ isn’t in the lineup, I think the article is still relevant because of the essential element(s) present in almost all the compounds, heavy metal: copper, zinc, and chrome to name a few. In other words, the heavy metal does most of the heavy lifting; from what I understand—the different vehicles and enhancers, like ammonium, or on the other end of the spectrum, acid, and either water or PDs, aide in penetration, stabilizing, fixing etc., during the processing of the wood. Many of the compounds listed in the article exceed residential use, which is quite specialized for safety, I believe. That's probably a little on the simplistic side, but I think the point is valid, regardless.
I’ve been encouraged in the last couple years by the improvements to the other “white meat” : borate-based preservatives. From what I’ve read, borates don’t build up in the body like heavy metals do, and the performance data has improved by large measure. Because ACQ-B/D lumber has a relatively huge copper content, and is currently popular, the borates look even more attractive. ACQ does turn a person’s thoughts toward copper futures though, ennit?