Pressure treated plywood for roof deck?
Can pressure treated plywood be used as roof decking without being destroyed by the dry heat a roof is exposed to?
I have a low sloped roof to replace where the 1/2″ OSB has rotted out at the edges and water has been penetrating behind the gutter and I am afraid will soon be into the interior walls, possibly even rotting the ends of the trusses sitting on the top plate. So far the place hasn’t fallen in and I can rebuild and reinforce what damage I find once I tear the roof off. What I am aiming at is redoing the mess and solving the problem, once and for all. I will use Storm Guard, 30 lb felt, with 30 or 35 year shingles. I always use the best quality materials and like doing things the right way with the best workmanship, only once. I am not sure this will completely solve the problems associated with ice damming or heavy downpours. But I thought if pressure treated ply were used at the most vulnerable places on the roof deck, even if water did seep in, the deck would not rot out again so readily. The other alternative is to strip the roof and completely rebuild a new, steeper roof. Even then there is a limit to the slope I could apply and if it’s a good idea, I’d use the PT plywood on that as well.
Has anyone ever tried this before?
Replies
not me!
Welcome to BT.
I think you're a WHOLE lot better off working at preventing the leaks in the first place. Treated plywood won't keep water out or keep other things from rotting or getting moldy.
Ice and water shield come to mind as a first defense. Checking out attic ventilation would be second.
In other words - Treat the problem, not the symptoms.
Carefully planned projects take four times longer to complete than expected, mostly because the planners expect their planning to reduce the time it takes.
What do you mean by low pitch ?
That could be your biggest problem in you are using shingles on to low a pitched roof.
We used 3/4" pt plywood for sheating on a flat roof in 1982. I recovered the pt plywood in 2002. It has been leaning agianst a tree behind my shop or used as walk boards since then.
Good stuff, that old CCA treated plywood.
Don't know about the the new ACQ treated.
Treated plywood isn't going to solve your problem if the roof pitch is to low for shingles. It is just going to hide the problem untill your rafters have rotted out.
Need more information.
I can't imagine any need for PT ply for roof sheathing ever.
Anytime PT is needed, the roof is not doing it's job and that is the place to deal with the issue. Let's plan to do that.
You mentioned low slope roof. That first had me thinking you had a BUR or steel roofing material but you are talking shingles.
What pitch is this? And what is your climate?
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That is what got me wondering too..
BTW we had to use the pt per the drawings. It was two layers of sheating with a steel roof over our CNG compressor station for our alternate fuel fleet.
(Bet the company wishes they hadn't given that thing away now.)
A properly constructed deck should not require use of PT plywood. You may need more of an overhang with functioning drip edges. Covering the whole deck with bituthane is an option, but this still doesn't address any overhang issues. If you decide to use PT sheathing, you'll probably want to use stainless or copper nails, but I really don't think that's an appropriate solution.
didit...Is it possible to share a couple photos of this roof situation with us?
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Thanks for all the input.
I did contact some plywood manufacturers and university architectural engineering departments today as well. What I found was, that all chemical pressure treatements weather-out. In an enclosed system, they will remain embedded almost indefinitely, hence they are used in pressure-treated foundations. Which I have been told are built in northern Canada! Imagine that, a wooden foundation wall! So, PT is an excellent usage on low or flat roof decks. If any slight seepage or moisture does occur, it does absorb more than other deckings and will not rot, nor decompose during drying out, and remain structurally sound throught many many years no matter what the conditions. I plan to use it along the bottom edge which should be plenty sufficient to resolve ice damming and any capillary action. Adding a wider 12" overhang and foam insulation a couple feet into the attic space should help as well. I also plan to blow in cellulose insulation when I open the deck up and add a ridge vent instead of those ugly vent caps.
Thanks again for the input. Always good to hear what others have tried.
I thought I was the only one who put PT plywood on a roof deck. We did an entryway for a 11 story building last year. The architect spec'd 3/4" PT ply with PT rafters. I could't get an answer why...now I have it.
Just use regular plywood and ice and water shield.
Is your archy planning on a leak too?
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
I guess...this spec must be in some college textbook.
The normal preference is to build a roof that will not leak through to the sheathing, nor wick water in at the edge. I don't think anyone here will disagree that PT is the way to go if you are anticipating that the roof will fail. If that is your expectation, then PT is the way to go. Good luck with it!
That's all well and good about PT weathering better and if it gets wet it'll dry and all that, but just remember then to do as Piffin said and use stainless steel or copper nails. Your roof won't last too long if the nails have all rusted away and the shingles (or the decking itself) are blowing off! (New ACQ-treated wood is corrosive, especially when damp/wet and will eat regular nails in short order!)
Edited 6/16/2008 8:54 pm ET by Danno
I just can't agree.
Using PT for residential roof decking is like using greenboard through the interior just 'cuz the walls might someday get wet.
It's adressing a symptom, not the problem.
Hell, why not treated rafters AND joists AND plates AND studs AND floor decking . . .
See where this is going? Where do you stop anticipating? Plus the cost of SS fasteners. . .
Forrest -
Edited 6/16/2008 9:07 pm ET by McDesign
I think didithimselfer got someone from somewhere else to agree with him and is not listening to the builders. There's nothing really wrong with using PT decking, just as there's nothing wrong with using greenboard throughout a house. Preparing for a leak rather than preventing it.
You can lead a horse to water, but you can't make him drink it.
--------------------------------------------------------
Cheap Tools at MyToolbox.netSee some of my work at TedsCarpentry.com
Edited 6/16/2008 9:45 pm by Ted W.
Edited 6/16/2008 9:45 pm by Ted W.
But you are missing the point. There is NO REASON in the world to plan for the contingency of this sheathing getting wet! I'm trying to help you build a roof that doesn't leak, but I need feedback to do that.
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
Well hey, who are we to argue with a plywood mfr. and the campus arky? I hope it rains like he11 in never-never land. --------------------------------------------------------
Cheap Tools at MyToolbox.netSee some of my work at TedsCarpentry.com
build the roof not to leak and take the money saved by buying regular sheathing and have a beer
yes, Wood foundations with PT lumber have been an accepted standard in the home building industry for a generation now. PT sheathing for decks is not. It is an anachronism.
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
In an enclosed system, they will remain embedded almost indefinitely, hence they are used in pressure-treated foundations. Which I have been told are built in northern Canada! Imagine that, a wooden foundation wall! So, PT is an excellent usage on low or flat roof decks.
Application - Retention (lbs/CuFt) - Uses:
Above Ground - 0.25 - Decking, fence boards, hand rails, deck supports
Ground Contact Fresh Water - 0.40 - Fence posts, landscaping, piers, docks, etc.
Permanent Wood Foundations - 0.60 - Wood foundations, crawl spaces
Poles - 0.60 - Building, transmission and distribution poles
http://www.treatedwood.com/products/preserve/
There are three ratings for PT lumber - above ground, ground contact, and direct burial. The PT plywood that's available in my neck of the woods is above ground only. So your comparison may not be valid.http://grantlogan.net
Who got Bo Diddley's money?
I am in northen canada.Prince Edward Island. I have been putting PT foundations in for the last 15 years.alot of them are only frost walls.e.i garages and small additions where basement space is not an issue.full height basements are constructed with 2x10,12"centers ,concrete footings. Once the basement is properly insulated etc. it is an extremely warm area. you dont have 10" of cold concrete to insulate against. exterior waterproofing is crucial but not difficult if done properly
I'd use the PT plywood on that as well.
With that mindset, you should probably use PT rafters, joists and studs. "Cause if the PT plywood was necessary, everything below it would also need to be treated. Better use that aforementioned greenboard as well.
http://grantlogan.net
Who got Bo Diddley's money?
And pressure treated blown-in insulation too! :)--------------------------------------------------------
Cheap Tools at MyToolbox.netSee some of my work at TedsCarpentry.com
Thanks for the advice. I see you used that on all your constrcution projects too. Must work real good.
>>>Can pressure treated plywood be used as roof decking without being destroyed by the dry heat a roof is exposed to?
Yes.
But why? As others have pointed out, it sounds like you're planning for it to leak. If so, adjust your design so it doesn't. Otherwise the building is doomed from the start.
Scott.
Always remember those first immortal words that Adam said to Eve, “You’d better stand back, I don’t know how big this thing’s going to get.”
Scott,
You at least seem to be one of the few intelligent and mature people on here with a opinion.
Have you ever seen what 13" of rain in 3 hours does to a roof? Any roof? 12/12 slopes even? Or 70+ mph winds, with driving rain? how about 6 months of winter? Ever walk down the street and see the ice hanging from second story roofs all the way to the ground like frozen waterfalls? 2' to 3' thick? Where the leaves didn't even get a chance to turn colors in the fall but are covered with snow all winter? Or 3 or 4 feet of heavy wet snow that crushes the roofs of commercial buildings? I have. And I've repair all such roofs just mentioned. This house in question happens to be in an area that has experienced all these weather conditions in the past 20 years. If I'm going to do a roof, it better last for more than 20 years without any problems.
Opinions are most often worth what you pay for them.
In closing, in all the 38 years I've remodeled and built homes I have retained 1 out of every 10 guys that came along with a hammer and often without a toolbelt, that tried to call themselves a carpenter. I have also kept 1 out of every 3 electricians, plumbers, masons and concrete finishers. The others were sent packing real quick.
I can always find a guy with a pickup truck and a hammer. But good people are hard to find, because they are always busy with work. Funny thing is that on a Monday afternoon I posted a question here thinking I'd get some reply from someone who knew something intelligent. Within an hour, I get all sorts of wise-guy ignorant responses and opinions from know-it-alls. But not one of them had any precise or accurate information nor directly answered the question. What were they all doing behind a keyboard on a Monday afternoon? Were these the same guys I fired, sitting back in the bar or at an internet cafe with a beer in hand on a Monday afternoon?
Usually I just sit around and read the messages and keep my mouth shut, granted there are certainly some sarcastic responses that are not warranted.
You asked for opinions and you got opinions...they are different than your own...so everyone else must be idiots. My opinion as well as many others is PT is not needed and a better solution is a better roof system.
>>>Were these the same guys I fired, sitting back in the bar or at an internet cafe with a beer in hand on a Monday afternoon?Well, if you're referring to Boss, Piff, Dave, McDesign, or Me, definitely not. Nonetheless, I wish you well with this project.Scott.Always remember those first immortal words that Adam said to Eve, “You’d better stand back, I don’t know how big this thing’s going to get.”
I thought pressure treated insulation was a good one. But then, I'm easliy humored.
Good luck with your project. If it were my house, you'd be the one getting fired.--------------------------------------------------------
Cheap Tools at MyToolbox.netSee some of my work at TedsCarpentry.com
I have asked twice now for information about your roof and climate so I can help you prevent the leaks in the first place.Are you ignoring that, can't read, or don't know what pitch roof and climate you have?
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
He had his mind made up what the answer was before he asked. I could tell by the way he asked it, which is why I cracked wise with my 1st reply.http://grantlogan.net
Who got Bo Diddley's money?
Well, he got so defensive there while ignoring all the good advice and comments that I missed seeing your first as a wisecrack. I thought you were serious - it was right on. I mean if he is going to plan for this roof to leak, he needs to plan how to manage his mold farm in the walls too.Anyways - in looking for yours again, I saw that there were about 16 serious replies before any goofy exaggerations crept in here and I'm still hoping he is capable of interactive dialog with a little prompting. My guess is that he is trying to put shingles on a 2/12 or 3/12 in a harsh climate but who knows if he can't reply to a simple question about roof pitch...
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
I will go along with you on your interpretation.
To the poster questioning why people were online during the day, I can thing of many reasons, including my own. I am 54 years old, worked in const. almost my entire adult life, including summers when I was a teenager, now recovering from a serious car injury. I can't believe that I have worked for you, if I did, I was the one that quit after the first hour because of your attitude!
What you said reminded me of a Sean Connery movie about a bank heist and he takes the fall for his grandson or nephew because Connery knows he woudn't be able to survive prison. On the way to prison or jail, all the prisoners are in the back of the truck and one of the detainees, a kid, keeps calling Connery "Pops," trying to egg him into a fight. Finally Connery says, "That's the third or fourth time you've called me pops...Do you have a picture of your mother? I've ####ed a lot of women, maybe she was one of them...." Then the kid jumps up and Connery beats the #### out of him. When the guards come and the kid is picking himself up off the floor, guard asks what happened and everyone, including the kid say he slipped and fell.
His first post gives some clues as to his locations Extreme wet and cold conditions only happen in certain areas, but no definite area. No answer at all on the % slope at all. I was surprised that any "quality" builder who has gone through that many carps and other tradesmen however has never heard of using an AWF as that type of climate is exactly where they are often used. He seems amazed and totally ignorant of the existence of such a thing. Makes me wonder.
They can't get your Goat if you don't tell them where it is hidden.
You and Piffen are likely right.
No answer to a simple question that would have given many of us an opportunity to give him good solid suggestions.
then come backs and rants about us and how many people he has gone through in 38 years of remodeling and home building.
Sounds defensive.
Sounds like someone is making the same mistake over and over agian for 38 years.
I make mistakes all the time. I try to learn from them and not repeat them. Doesn't always work , but I keep trying.
My epitath will we one word "OPPS"
I vote TROLL!
Comes on asks one question, disregards all serious responses and then bails. A troll I tell ya.
Doug
After reading all the posts I have to laugh. Anyone who comes on the forum and askes for advice should take into account all the years of experience he has tapped into. After too many years as a tradesman, manager and then back to being a tradesman I have found that on all jobsites there is round of discussion on any thorny or not so thorny issues, and I have never seen someone who has made there maind up so completly before asking the question. Good luck with the roof, but it will most likely still leakhttp://www.holtzheritage.com
Yep, and not even a very good one at that!
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Piffin
In all my years of doing this stuff (construction) this is probably the first time I ever saw/heard of anybody wanting to do a roof like this guy?????
Maybe it's one of those regional things!?!?
Doug
Region 86, I think
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
Area 51....
Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming<!----><!----><!---->
WOW!!! What a Ride!Forget the primal scream, just ROAR!!!
I can sort of see it--you think, well, if such & such is good, but this other material is better for a somewhat similar application, maybe I should use this other marvelous material. Similar, IMO, to people who want to glue and screw the frame together. Really, if you think about it, granite countertops fall into the same category. Not really the right material, but sure looks pretty and adds lots of status! The same concept of, "If 4 nails will hold it well, twenty should make it nearly perfect!"
IMO, people should be putting the extra care and better materials into the foundation, although the roof is almost as important--water getting in can really mess up the house! I used to like watching TOH where they would run out of budgeted money and have a huge barn-house with all the bells and whistles, but it's sitting on a failing fieldstone foundation because they didn't have money to re-do the foundation--they'll do it later when they have money. I'm guessing they'll never quite get around to the foundation unless something drastic happens.
Wow, you sure know how to make friends.
Did it occur to you that this forum spans several time zones? That while in the middle of your day it may be beer and computer chatting time for the pro's who are 3 hrs ahead of you?
Daniel Neumansky
Restoring our second Victorian home this time in Alamdea CA. Check out the blog http://www.chezneumansky.blogspot.com/
Oakland CA
Crazy Homeowner-Victorian Restorer
Not to mention it might be the wee hours in the Far East or Europe, where some members are from.Rebuilding my home in Cypress, CA
Also a CRX fanatic!
If your hair looks funny, it's because God likes to scratch his nuts. You nut, you.
Thanks for fending for us, madmadscientist (man, that's a lot to type!).
I, for one, was home on a Monday afternoon. I was installing some glass block windows and too close the the computer to resist visiting BT every hour or so. I didn't respond to his outburst because I don't give a rat's butt what he thinks.
I'm guessing all those workers he claims to have fired actually walked, assuming he's not telling a big fat lie. The latter is my guess. To be honest, I don't think he's a contractor at all.
He may follow the good advice he found here or he may not. If he does, he'll never admit it. Personally, I don't care if he uses Saran Wrap.
But thanks for sticking up for your fellow BT'ers.
BTW, he's not invited to the tavern! :)--------------------------------------------------------
Cheap Tools at MyToolbox.netSee some of my work at TedsCarpentry.com
"That while in the middle of your day it may be beer and computer chatting time for the pro's who are 3 hrs ahead of you?"
Or they might have been sitting at the computer in the middle of the day. Nothing wrong with that. They might have a sandwich and stay up late tonight too. Who knows what devilry feckless builders are capable of.
Edited 6/21/2008 3:13 am ET by fingersandtoes
yep.
Take me for example, sat on my duff for almost 8 months. Didn't collect unemployment, welfare, food stamps, state aid etc. etc. Now I will work my #### off for 10-12 hours a day 6-7 days a week for the next 8 months so I can do it again next winter if I choose.
Crazy as the rest of you all I am .
They can't get your Goat if you don't tell them where it is hidden.
on low sloped roofs in atlantic canada a torch on product is used often. the product is heated to melt the back side heat sealing to the substrate and all seams. this is one roof that will last one hell of a long time. its a rubberized product
I re-read your original post after I'd gone through to the end of the posts, some of which were getting downright nasty! Anyway, Bosshog had a very good idea right out of the gate--first reply to your post--and that was to use water & ice shield. This is a self-adhering, tough, rubbery material that comes in rolls with a slick backing sheet. You are probably familiar with it. Most people use it only at the eves, but for more "insurance" you could use it on your whole roof instead of tar paper (felt). It seals nails and once it sticks down, it is down. I think that would give you better protection than the PT. You can also get the same product in a 12" wide roll for starter. Since it is continuous and self sticking, it is far superior to the usual starting course of trimmed or upside-down shingles.
I always use the best quality materials and like doing things the right way with the best workmanship, only once.
When you say "best quality" materials, I'm assumming you mean the best material for the job at hand. As others have noted, it probably won't hurt to use PT for the sheathing, but there is also no clear advantage to using it and it does create some issues with fasteners. IMHO, the best material for roof sheathing is Huber Advantech. It will resist rotting and swelling with exposure to moisture.
But, as others have mentioned, you're trying to treat the symptom, not the disease. If you want to do it right the 1st time, get a roofer that knows how to install a roof and flash it properly. There should be no reason to use PT plywood for roof sheathing and it certainly isn't the best material for the job. Good luck.
http://grantlogan.net
Who got Bo Diddley's money?
Dude, the first thing you need to do on this particular forum is fill out your profile. There is SO much variation in building practice that depending on climate, one solution ment for one area will destroy a home in another. Yes, we do normally check profile information on someone we don't know before we post a possible answer.
If you are willing to tear off the whole roof as you stated, then actually doing the roof right (not just good enough as it was previously built) should be pretty easy for you. Start with better materials - the PT decking may sound good based on the symptoms, but having your shingles or other coverings come off in those 70MPH winds due to fastener corrosion is a real risk.
A roof is a system, and super-dupering one component won't make a difference if the rest of the system is crud. That's like dropping a 600hp engine in a Geo Metro - it won't go very far without beefing up the tranny, axles, tires, brakes, engine mounts... you get the idea.
To improve your roof you need to improve your whole system. Ice damming happens because heat melts snow... so why is that happening now and how are you going to keep that from happening in the future? Will this change how your roof system is ventilated? Driving rains are a risk in your area, so what materials do you use under your primary covering anticipating the first layer may be breached? OK, what if that 2nd layer is breached? OK, what about that 3rd layer? Flashing details are critical, and it sounds like they were done wrong on the roof in question, so how will you redo them correctly?
In case you care, I'm answering this at 1pm, Cali time. I'm a stay home dad whose 2nd job is rebuilding his house. I rebuilt about 1/3 of my roof (including raising it 12"), correcting previous mistakes in design and construction as well as bringing it up to current seismic code. All with the generous help of the other A-holz on this board!
Rebuilding my home in Cypress, CA
Also a CRX fanatic!
If your hair looks funny, it's because God likes to scratch his nuts. You nut, you.
If you feel the need to use treated plywood due to moisture damage on a roof application, you are thinking all wrong.
The plywood my survive, but moisture, if it is there will be a problem.
Build it right so there is no moisture ... millions of houses can't be wrong. It's done every day. If there is a problem, figure out what it is and when repairing/replacing, take care of it. Pressure treated plywood is a waste of money in this case and you'll think you solved the problem and in actuality you may not have.
I think we have been added to the long list of people he has fired for not going along with crackpot ideas.
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
hello, i read messages in this post and think you do have a good point about using PT plywood vs regular plywood. Incase the roof need to be repair after 10 years maybe PT plywood would still be in good condition to use instead of replacing water demaged plywood. It might be a over kill by some options, but it might be a cheaper way if you consider cost of tear down the plywood 10 years later. Just like some roof shingle company would void warranty if use oriented strand board (OSB) instead of plywood. If argument for PT plywood vs regular plywood hold true for roofing, does it also apply to regular plywood vs OSB? I don't have too much experience with roofing, but i know i would use plywood over OSB for roofing, so i can see using PT plywood over regular plywood.
dzone
You might want to go back and read all the messages. I think the overwhelming opinion of the board was it's a waste to use PT plywood on a roof.
thanks.
used sheets of advantec flooring
For a low pitched porch roof I used advantec flooring tig (4'x8') sheets.
Was planning on using PT but they were so warped and the advantec looked much easier to get the tig to work I bailed on the PT. SO glad I did now! Then I painted about 6-8 coats of the white elastomeric sealer(koolseal and then the black jack brand-lowes switched brands midstream) only on the top. Duration on the bottom-which is what you see while sitting on the porch.
Has worked great now for about 10yrs. In a coastal environment too. SUrvived hurricane ophelia and multiple other tropical storms here on the NC coast.
Now using sealoflex on an old metal roof(different project). Covers very nicely. My 1st experience with the sealoflex brand product but is double the cost of the black jack elastomeric from lowes.
Pressure Treated is GOOD
I hate these sites.
Too many "experts" with too many OPINIONS.
Read the poster's question. Stop giving advice as it only appies to YOU.
The man wants to put PT plywood on his roof. What's wrong with that? If he feels better doing it, that's what matters. It won't harm anything. STOP CRITCIZING.
The idea (that everyone is missing) is that the eaves are the first to rot out. They are also the most difficult to notice a leak since the water runs THROUGH them and not into the house where it would be imeadiately noticed.
It would take a much longer time for the rafters to rot than the decking. It is also less likely to fall through a roof that the decking is good but the rafters are weak.(NOTE: LESS LIKELY - so don't go off on that too.)
His idea of PT plywood over the eaves is a very good idea.
I have spent my life listening to what "experts" say and found most of their info was based on "THEM" or what "code" is or other undocumented info. (New house with all their "preventative building measures" don't hold up like older houses do.)
I have actually constructed buildings to test all these opinions and theories. One was actually a roof systen with PT plywood. While all the other (identical) houses suffered roof rot, mine -after 40 years - is still strong. (I used hot dipped galvanized screws and they are still strong.)
It is inevitible that the eaves will likely leak or rot in a lifetime - NOTHING is forever - so why not PT.
It's ironic - and must be noted here - that most of you naysayers are probably selling homeowners the idea of longer lasting products that you think are better and make more profit for YOU. The others that think anything is "good-enough" would NEVER do work for me.- these people - do the least work for the most cost.)
Why shouldn't he replace the plywood with the best type? What's wrong with preventative measures? (Isn't that what code is supposed to be about anyway?)
(BTW, I put a 15 year roof on my PT roof sheathed house and it is still holding up 40 years later. IDK if the decking is a factor - there's absolutley NO WAY to find out.)
NO ONE can EVER determine what lasts and what doesn't and for how long. There are too many variable factors. My theory is; Build the best you can and when the inevitable happens, you will feel better and more secure that it won't be as bad as a skimpy constructed catastrophy.
The most important things I've learned in construction; architects rarely visit the building sites to explore their theory of building, builders cut every corner to make more profit, builders rarely go back after a few years to see how products held up, codes are designed to proect the stupid, cheapness always costs double. "New technology" is always something that costs more and fails sooner. (Lawyers are always around once things fail.)
DIDITMYSELFER:
Use pressure treated on your project. After, if it's possible, investigate rubber roofing. It, too is very long time durable and less likely to leak if applied properly. Good luck and good spirits.
I have a degree in architecture and building construction and technology. I have personally (and all by myself ) built 12 homes from the ground up including ALL systems (and I periodically go back and examine so I can learn "truths" about building. Five of my houses were "experimental" - all doing great! And I have inspected thousands of homes.(My "hoddy" is also the history of the house and I have been consulted many times about historical buildings. I consider myself an expert in this field - whatever that means.
You know what I hate? Self proclamined experts who come on here responding to an 8 year old thread like anyone cares.
Why? Do you have an insect problem? When I was rebuilding a pontoon boat I talked to the manager of a Wolman plant (that makes PT lumber from anything you take them)
He said it was a waste of money. PT really just protects from insects and other living organisms (fungus etc). If it stays wet it will rot and delaminate almost as fast as regular ply wood.
He said if I want to protect plywood from water, seal the edges. I did that and 25 years later, the deck on my boat is still solid (salt water, regular use)