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MntGoat
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# Posted: 4 Nov 2019 21:57
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PT all the way. I dont want to ever deal with a rot issue and I dont want my kids to either.
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KinAlberta
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# Posted: 4 Nov 2019 23:54 - Edited by: KinAlberta
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Quoting: ICC paulz, I did not see any references to color and type as to old/new in the linked document either. Is the green stuff you are wondering about a more green-green or a more olive-green. Both the old CCA and some of the newer treatments use copper and that is where the green color comes from. The newer types don't have the arsenic or other heavy metals. The newer tend to be less green, more olive toned. I believe the tans and browns are all going to be one of the newer types. Both old and new come in different retention rates; above ground through foundation and salt water grades. And that is the big decider as to where it can be properly used.
Borate limitations, incising and colour:
(A lot more information at the link)
“... Wood products treated with borates are available in both countries. However this is not an equivalent to CCA, as borate-treated wood may not be used outdoors exposed to rainwater (borate preservatives do not bond to wood as well as CCA, which means the preservative can eventually wash out and thus leave the wood unprotected). Borate-treated wood is well-suited to applications that are protected from exposure, like sill plates. ... WHAT IS INCISING AND WHEN IS IT REQUIRED? Incising is the process of cutting many small slits into the surface of a piece of wood in order to increase the amount of preservative taken up by the wood during treatment. Some wood species are particularly hard to treat, and incising is necessary to meet the penetration requirements in CSA standards. Non-incised CCA- treated wood will have a shorter service life than incised CCA-treated wood, but the difference may not be noticeable in the short term (under 20 years) in relatively low decay hazards such as decking. For wood in critical structural applications under conditions conducive to decay, incising could make the difference between 4 and >40 years service. Incising is not necessary with borate-treatment, because borate diffuses to achieve the required penetration. With borate-treated wood, there in no difference in performance between non-incised and incised, provided the target chemical content is achieved. There is a strength-loss penalty for incising, which is addressed during structural design. WHAT'S THE DIFFERENCE BETWEEN GREEN AND BROWN TREATED WOOD? If you are shopping for treated lumber at a do-it-yourself retail centre, you may be confused by the choices and store staffers may not know much more than you do. Whether the treated wood on display is green, brown, or bears a brand name, it's all been treated with a copper-based preservative. The brown products have merely been coloured to mask the greenish tone of the preservative. This colouring is not permanent and may fade away, leaving you with wood that looks the same as the green version at the store. Note that the green tone of treated wood will fade as the wood ages, without any effect on the wood protection. https://cwc.ca/wp-content/uploads/2019/03/FAQ-durability-Treated_wood.pdf#page5
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KinAlberta
Member
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# Posted: 5 Nov 2019 00:08
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#10 is on PT vs bugs
Wood Myths: Facts and Fictions About Wood | Building and Construction Technology | UMass Amherst
https://bct.eco.umass.edu/publications/articles/wood-myths-facts-and-fictions-about-w ood/
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Brettny
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# Posted: 5 Nov 2019 08:05
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Any wood within 1in of concrete or in a splash zone should be PT and not the non ground contact junk. Also you should separate even GC PT from concrete. As for making every floor joist and your sub floor out of PT that may be a bit overboard if your well off the ground.
As for bug resistance im not sure. Bugs are a big variable that can change with climate, season and can be dif in 10yrs.
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MntGoat
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# Posted: 5 Nov 2019 22:28 - Edited by: MntGoat
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Better to overbuild in my mind. I bought a 40 year old building on sonotibes and some of the sills were rotted despite being 12" off grade.
When I built this cabin I did not want any issues and used PT for joists and PT decking as seen in my above pic.
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Brettny
Member
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# Posted: 6 Nov 2019 05:34
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What do you mean by sills? The rim board?
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MntGoat
Member
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# Posted: 6 Nov 2019 05:57
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The rim board is what I am talking about, the rot did extend into some joists as well.
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Brettny
Member
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# Posted: 6 Nov 2019 07:17
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Thats one board i would always use PT on. I had to repair some rim boards and joists on my 1930s house as well. It could be because it had no gutters for many years or was poorly taken care of.
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KinAlberta
Member
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# Posted: 7 Nov 2019 23:28
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If PT is used, people better read up on fasteners, hangers, etc.
ACQ type deck screws have severe limitations.
Stainless steel screws should work. However what’s the code?
Nails?
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ICC
Member
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# Posted: 8 Nov 2019 00:07 - Edited by: ICC
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The IRC, Section R317.3.1 states: "Fasteners in contact with preservative-treated wood shall be of hot-dipped zinc-coated galvanized steel, stainless steel, silicon bronze or copper."
Maze Nails makes some good double hot-dipped galvanized nails that are suitable. There are other brands but check before use because not all hot-dipped galvies meet the ASTM standards. Electroplated galvies, the shiny type of galvanized nails, generally do not meet requirements for ACQ.
Stainless steel fasteners should be grade 304 or 316 IIRC. I forget the number but there are also some S/S screws made from a magnetic stainless grade that are also suitable for ACQ. Made for metal panel use they come in assorted head colors. They are handy when using drill-drivers and a magnetic bit.
A permanent wood foundation must use stainless steel fasteners to meet code, so that is a hint that perhaps choosing S/S for any pier and beam using ACQ treated wood should also use S/S for best life.
GRK makes an assortment of screws that are ACQ approved. They have sizes made for ACQ deck board use. They use a special coating that exceeds the hot-dipped performance.
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Brettny
Member
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# Posted: 8 Nov 2019 07:06
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Fasteners in PT is good to note. Its not just the expense of PT wood but fasteners also. I know for my Bostich nail gun galv nails are almost 2x the price of normal nails.
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ICC
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# Posted: 8 Nov 2019 09:45 - Edited by: ICC
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Quoting: Brettny I know for my Bostich nail gun galv nails are almost 2x the price of normal nails.
The fact that the fasteners are more expensive than other non-suitable ones could be looked at as another reason to not use PT wood in places where it is not necessary. However, if the location demands the use of PT wood then one has to suck it up and use the right stuff, including any metal brackets, post bases, hangers, etc. or it is all for naught.
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MntGoat
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# Posted: 10 Nov 2019 20:38
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I did have to spend more on fasteners. It was a very small up charge when compared with the total amount I spent on the other materials. Peice of mind for me.
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Fishntime
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# Posted: 22 May 2023 19:39
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I’m having a 14x28 cabin built on 6x6 pt skids. Question is I have the option to up to 2x8 pressure treated floor joists from the standard 2x8 KD pine joists. Is it safe to use pressure treated joists in my type of build? Got a young family and concerned about chemicals in pt. Any advice Thanks Located in Maine
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gcrank1
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# Posted: 22 May 2023 20:39
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The PT wood is not going to be in human contact, in fact, well sealed away from you.
Imo, You are likely exposed to far more harmful chem in the air in any urban area then you will be from PT under your floor decking.
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ICC
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# Posted: 22 May 2023 21:50 - Edited by: ICC
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+1. Absolutely. Use PT, unless you want the bottom to rot out.
Don't let the kids crawl under the cabin and chew on or lick the PT wood though.
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Brettny
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# Posted: 23 May 2023 08:03
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My shabin. Temporary cabin has PT plywood sub floor. We have foam tiles on it. Feels good underfoot and adds a bit of insulation.
I would definitely use PT for runners. If the building is going to be on blocks I wouldnt bother with PT floor joists.
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Fishntime
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# Posted: 23 May 2023 09:15
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Cabin will sit on gravel 8-10†gravel base with 2 6x6 pt skids running the the length of the cabin. So basically 6 inches off the ground no crawl space. This will start out as a seasonal cabin and hope improve from there. The additional cost for the pt floor joists is $550 cabin is under 400 square feet. Was just not to familiar with the use of pt lumber pros and cons. Any recommendations are greatly appreciated. Thanks for the input.
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ICC
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# Posted: 23 May 2023 12:03
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FWIW, codes usually stipulate that beams touching the earth or less than 12" above the earth be PT with 18" the distance for joists.
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gcrank1
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# Posted: 23 May 2023 12:34
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A year or so ago we built a 10x24 deck on one side of the cabin, less than 12" from ground. Ive seen enough decks built higher that did not use PT that had rotted beneath the deck boards so any deck I build will be PT.
And that was 'just a deck'.
You will likely never regret using PT under your cabin vs the uncertainty of what is going on under there over time. It isnt like you can just pick up the shell off the decking to rebuild it.....
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Fishntime
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# Posted: 23 May 2023 13:50
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Thanks for the advice guy’s. My order is in and I did go with the 2x8 pt upgrade.
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Brettny
Member
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# Posted: 23 May 2023 19:29
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Make sure you use hot dipped galvanized hardware or hardware rated for contact with PT. It's not just spending a bit more money on the wood it's all the hardware too.
GCrank no where should a deck use non PT floor joists. It's to exposed. You can replace floor joists and I have. It's really not that terribly hard. I had a basement that has an artesian well in it and it was so humid down there for so long the floor joists rotted. I just sistered them up. Then fixed the moisture issue.
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