When roofs do rot, which side does the rot start on? worth using copper-borate treatment as preventative?
mikkelsen
| Posted in General Questions on
When roofs do rot with closed cell foam underneath, which side does the rot start on?
Is it worth using a copper-borate treatment as preventative?
Zone 6. There will be 4″ 2lb closed cell foam on the underside of the sheathing. tar-paper on top. Attic space will be living space. not expecting to have any rot issues but….I’m thinking a belt-suspenders approach here. considering spraying whichever side is prone to rot in this situation with a copper borate solution as a preventative.
thank you.
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Erik,
First of all, the vast majority of reports of rotten sheathing on roofs insulated with spray foam involve open-cell foam, not closed-cell foam.
Second, if I had to guess, I would guess that the most likely source of moisture that could damage the type of roof you describe would be a roof leak (assuming, of course, that your spray foam contractor does a conscientious job when installing the foam).
Third, if you really want to take a belt-and-suspenders approach, the best way to proceed would be to install a vent channel between the top of the spray foam insulation and the underside of the roof sheathing. You could do this by installing site-built baffles (I would use plywood) attached to "sticks" in the corners of each rafter bay. Of course, this approach assumes that it is possible to install soffit vents and a ridge vent.
Yes, and thank you Martin...I had wanted to do that but the way that a large section of my roof had to be framed has rafters running perpendicular so I cant get a vent channel in those areas.
Eric,
Should you elect to install any additive to prevent sheathing rot, you need to consult the SPF chemical manufacturer first to be sure there will not be an odor problem or chemical reaction. Whatever your choice, make sure everything is put in writing between you and the chemical maker and the installer. Whatever the installer claims verify it with the chemical maker in writing. There's nothing worse than finger pointing and no insurance when odor claims arise.
Treated lumber to avoid rot in a roof system isn't really a "belt and suspenders" method, it's more of a "band-aid" to compensate for a design problem. As Martin says your best bet is to include ventilation. Regardless of which way the rafters run you can vent above the sheathing by adding 2x4s (laid flat) running eave to ridge and then a 2nd layer of sheathing.
Why not use a product like Prosoco Cat-5 liquid applied barrier? It's rated to 150MPH and resists water and air intrusion but it is also vapor permeable so it can dry if water does get through. You can roll-it on or spray it on.
Also, why are you using "tar paper" or building paper? In a Zone6 climate you will have ice/snow build up on the roof and tar/building paper is useless when it comes to dealing with that.
What kind of roof are you putting on top (metal, tile, etc)?
The 4" of closed cell is basically vapor impermeable. The exterior roof OSB sheathing will NOT dry to the inside if it gets wet but if you put on a metal or asphalt shingle roof, it will not dry to the exterior either.
I'm not familiar with the liquid barrier...it is used in replacement of an underlayment?
The roof material is a synthetic shake and it has considerable air space behind it. It looks like moisture could find its way out evaporating but I don't think that has ever been tested on it but there is considerable air space and paths for air to escape.
The material sheds snow and the roof is a 10/12 pitch with no valleys so no snow and ice will build on it.
I'm wondering with the air space behind the molded shakes, if the plywood sheathing would benefit from the treatment of the copper/borate solution.
...I know the sheathing would benefit, so more accurately, I'm wondering if the application of the solution would be justified/worth the time & cost.
I would call Prosoco to find out what they say. They said it can be used for soffits, fascias, window openings, and vertical surfaces. Check out their website.
I don't recommend the treated copper/borate solution because it might cause streaking and staining of your roof and walls. I would check with the manufacturer to be sure. It might be OK but better to ask.
Building paper has a rough life on a roof and over time will begin to degrade. It's not the synthetic shake that will fail but the building paper underneath it. Depending on climate/elevation building paper on a roof might have a 10-25 year life before it needs to be replaced.
any felt paper that is built for more longevity? would two layers make any difference or would they both fail at the same rate?
Eric,
As long as it isn't exposed to the weather for very long before being covered by roofing, asphalt felt will perform just fine and will last for decades. The 30# felt is heavier than the 15# felt.
Your wanting to know if copper-borate will bond and sustain to phenol resins used in OSB-plywood as a moisture-air barrier perhaps with the correct engineering-manufacturing at the OEM level. When the sheathing wood chips or plys are manufactured to the surface or edge rather than the phenol resign and put in contact with a food source found in open or closed spray foams, that is when rot and fungi happens, dry-rot does not even need moisture. The best one to ask is the sheathing manufacture because as some may know phenol comes in many grades, about as many chemical compounds you will find in foams (closed or open) needing a chemist to answer your questions properly. One thing the sheathing Engineer should point you to is the exposure class on their product label data sheets, venting can in some cases exceed the limited exposure class rating to moisture-acids-salts-etc. Plywood in general does a better job and has a higher exposure limit than OSB, other than looking at the ZIP products that are higher, especially when fasteners are installed potentially exposing the wood.
CAT 5 uses a calcium carbonate (left over junk from making calcium oxide or quick hydraulic lime), it's binding strength will not be near the strength of hydraulic lime or high calcium oxide. "Proprietary Polymers**.....? probably some more inert fillers or plasticizers to cut cost...there is a risk when companies do not want to disclose chemical contents, you never know what you are getting. Take note: INCOMPATIBILITY (MATERIALS TO AVOID): Avoid contact with acids and oxidizers
http://www.prosoco.com/Content/Documents/Product/RG_Cat_5_MSDS_C_050713_C.pdf
WARNING!!! Read the labels.
You do not want to do post-construction treatment of your roof with copper-borate. You can buy pressure treated, kiln dried, ply. But don’t spray this stuff on your house.
Read the MSDS for these chemicals and go on OSHA, NIOSH, and EPA websites. Spraying your house with Cu-Bor would be akin to the idiotic method of removing radon from inside the house by pumping it above the house (vented on the roof) so it can cascade (its heavier than air) down the outside of the building onto the grass, sidewalks, driveway, pool and playground area, and be pulled in by E/HRV's, air conditioners, open windows in the kid's bedrooms, etc.
I use copper borate to treat posts, girders and beams. I use copper powder mixed with water to spray orchard crops. My dense packed cellulose is pretreated with borates. My preserved wood foundations and any lumber in contact with the ground or constantly wet is purchased pre-treated with copper. But we don't spray it on or put pretreated adjacent to our living space and the on the mateirals that contain our conditioned space.
http://edis.ifas.ufl.edu/pi103
http://www.cdpr.ca.gov/docs/emon/pubs/ehapref/pesticidal_copper_%20oxide.pdf
http://npic.orst.edu/factsheets/borictech.html
pressure treated wood is in every basement.
I see no problem using pressure treated plywood for roof sheathing.
Show me a source that says otherwise.
As to what is best, use standard high grade plywood or Zip sheathing and vent.
Venting is key.
Vent.
The key to energy efficiency is to seal up the ceiling plane well so your wonderful venting does not vent away your energy savings.
lunch break is over
If you sheath your roof with ACQ plywood you will need different roofing nails and can not use aluminium flashing, roof vents, trim or skylights without elaborate measures to separate them from exposure to the copper in the treated plywood.
AJ .. for one thing, the PT lumber and sheathing in a preserved wood foundation is driven in by pressure, moisture and heat. It is not sprayed or painted on after construction. The toxins in commercial PT lumber (which I recommend if you read my post) is significantly less bioavailable than a spray or powder after the fact. That would not only fail to protect the wood, it would fail the health laws of the modern world. Copper is a poison. Read the URL’s I posted previously if you don’t believe me. And this public website should not be promoting practices that are health hazards to builders and their workers, residents and home owners.
Secondly, open PT or Cu-bor preserved wood inside the human or animal living space is toxic.
http://pmep.cce.cornell.edu/profiles/extoxnet/carbaryl-dicrotophos/copper-sulfate-ext.html
Why the over emphasize on wearing gloves when handling PT lumber: because copper splinters are toxic.
http://www.woodpreservation.ca/index.php/en/residential-use/faq
The fasteners can only be stainless steel. Galvanized and other fastener materials will corrode through within a year.
Fitch,
There are differing grades of galvanized fasteners. Some are rated for ACQ and hold up fine.
ACQ (Alkaline Copper Quarternary) replaced CCA and wolmaniized treated lumber since it contained aresenic that leached out to soil in childrens playgrounds, as a result of a public outcry around schools. In this application, it is not a copper ag or oxide product so lets not get confused, it is a hydroxide solution dip. It is manufactured in a bond tool with vacuum pressure and/or tooling pressure, heat, to a retention level and number of allowable voids in the bond line, and different ply thickness or chip size. Smaller voids and higher retention are marine grade ok for salts, lower construction ground contact, and above grade lowest retention-void. The copper compound is considered contained or embedded, if you sand it particles can be become air born and a heath hazard. Read the MSDS not ag sites or other applications.
Galvanic corrosion can occur anytime dissimilar metals or materials are in contact or a distance apart depending on the cathode-anode strength of electrons, unless a chemically inert isolation material breaks the charge such as mineral wool or glass. Electroplated, brass, or aluminum fasteners or flashing should not be used. Stainless, hot dipped galvanized if they comply with ASTM A 153 class D are ok. You can encapsulate most any fastener with a inert sealant.
So OP you can see what I said earlier that if you are the manufacture you can change the retention and void level to different acceptable exposures or applications. Just applying a spray top coat will do nothing, nor sustain, may be toxic if placed against certain acidic soils or foams (open or closed does not matter, chemical compositions does).
Gents ... top grade, hot dipped galvanized nails are what is recommended as one type of fastener suitable for PT lumber above grade (.40 PCF). For the ground permanent contact and marine grades, only stainless steel is used.
Simpsons Strongties claims appropriate use of its hot dipped galvanized fasteners and brackets for .40 PCF (lbs per cu ft). According to the APA (American Plywood Assoc), .60 PCF (20% greater concentration than the concentration permitted for use with galvanized fasteners) is foundation grade.
PS. ... don't put aluminum flashing, or steel and glavalume roofing near PT lumber. Don't place PT lumber over any regular framing where standard nails and screws are used if there is any chance of the PT lumber getting wet enough to leach out the copper ... which it does. It will destroy aluminium windows, cast and formed steels, wrought iron, bronze, ardox nails, deck screws, etc.
http://www.estainlesssteel.com/corrosion.shtml
There is a new kid on the block called "micronized or nano-copper" wood preservative. Produced by former “Osmose, inc”, now “ Copper Performance Chemicals” probably a new company for liability asset protection…ha! http://www.koppersperformancechemicals.com/...
Their “terms and conditions” are interesting especially the lack of liability, E&O, and warrantee.
Data & MSDS:
http://www.koppersperformancechemicals.com/pdfgallery/pdfs/mp-lifewood-msds.pdf
http://www.koppersperformancechemicals.com/micropro/micropro-features.html
http://www.koppers.com/pages/terms-conditions
Not endorsed by AWPA ( http://www.awpa.com/contact/index.asp) but claims to be “third party tested” and NAHB approved.
Under fire from environmentalist that claim,
“ICTA believes that EPA must act promptly to protect the public from unintended health and environmental hazards resulting from further widespread commercial distribution of Osmose’s registered nano-copper wood preservative pesticides. As we will show infra, there is substantial scientific evidence that nanoscale copper and copper compounds are highly toxic. And even though EPA has not yet evaluated the safety of the Osmose products containing “micronized” copper carbonate, the company stated over a year ago that: “Over 5 Billion board feet of MicroPro treated wood has been sold since the product introduction in 2006.”10 EPA has ample legal basis to cancel the registrations, to determine each is void, and/or to take enforcement action concerning the sale and distribution of these products. “
ICTA is claiming Osmose.inc misrepresented the size of the milled copper oxide that gets suspended and injected into the wood vs ACQ that is a copper solution infused under heat and pressure. From what I gather, the small particles or “dust” (90% listed in their MSDS along with copper carbonate) can leach out, become air or ground borne. It does not get as wet or take as long to dry out as ACQ and is more corrosion and fungi resistant to fasteners and is ok against aluminum they claim, but, if the copper leaches out that can make it vulnerable. Their MSDS list “reducers and oxidizer” to avoid contact with. It is not clear to me how they are isolating copper and aluminum galvanic corrosion…more on that,
Reducing agents and oxidizing agents are the ones responsible for corrosion, which is the “degradation of metals as a result of electrochemical activity”. Corrosion requires ananode and cathode to take place. The anode is an element that loses electrons (reducing agent), thus oxidation always occurs in the anode, and the cathode is an element that gains electrons (oxidizing agent), thus reduction always occurs in the cathode. Corrosion occurs whenever there’s a difference in oxidation potential. When this is present, the anode metal begins deteriorating, given there is an electrical connection and the presence of an electrolyte.
Several reducing agents in SPF’s can be found listed here:
http://en.wikipedia.org/wiki/Reducing_agent
I personally would not trust their claims until the EPA and AWPA regulates them more, if they have nothing to hide why not? When you mix products such as open or closed cell foams with treated lumber there are potentials for corrosion, fungi, and rot. A risky assemble and do not think internet only field data is enough to draw conclusions. What is enough is a well known fact that when you mate materials you should know what you are doing or go get someone that does.
Interesting firestorm of thoughts
Where I am... ACQ has been replaced by the micronized treatment and they say that it is like the older pt that was not as corrosive as ACQ. And as Terry Lee says... you need water to aid the electrolysis. Dry materials are not the problem wet ones are.
Any hoot.... vent and use plywood or Zip products. Do good work. Flash correctly.
As to toxic.... I have handled thousands of PT boards without gloves and am still here posting and yapping. And what about people manufacturing PT. I don't here of them dropping dead by the millions.
The word toxic is so vogue today... Everything is toxic. Life is toxic. This site making improper recommendations is toxic. I am toxic. My posts are toxic.
The sun is shining wonderfully today for me anyway even though it is so so toxic why we must wear sunscreen. Just read a blog now that says to lather up your children with sunscreen everyday before school because they "may" have a few minutes of sun exposure if and if.... they happen to have an outdoor session of gym class... for 20 MINUTES!!
The kids I know with health issues have parents that wear rubber gloves all day and spray cleaners 24/7. Toxic dirt or the cleaner? Or the overthinking parent?
Toxic... yup I am toxic. Have dirt all over me daily... When I shower at night I get a thrill out of seeing it all hit the drain. Cleaning dirt out of my nails for life.
So Flitch you use redwood or what for sill plates since you are not a PT guy?
Terry Lee, always interesting posts by you, thanks for the inputs.... same for you Flitch.
AJ ... your old man of the mountain routine doesn't fly with me. I am an old man on another mountain. Not so far from you I think (western NY). I gladly use copper treated lumber and cu-bor to protect my property; and of course I use copper powder on my orchards and gardens.
But that don't make it safe when someone thinks they can spray it on a roof deck. That is plain stupid and you should be more responsible than offhandedly dismissing the risks. Which gives readers the impression its sissy to be concerned about chemical toxins in the building industry ... a particularly toxic industry, to be blunt.
Handling PT lumber with bare hands is not so brave. I used to handle dioxins with bare hands. But I am pretty sure you (and I am sure I ) would not use dioxins with bare hands today. And I see lots of millionaire farmers with their kids with PhD’s in agriculture spraying pesticides on orchards without masks. That is not something to brag about.
Ainsworth Lumber website stated that they offer Zinc Borate Treated OSB panels.
Peter, have you read Ainsworth's warranty? It guarantees the product as long as it never gets damp or wet.
That is because borate is soluble. The zinc - copper are the sacrificial anode until it wears out hence the limited warranted. Both are good anti-fungi and insect, fire retardants. If the manufacturrd used a hydroxide it has a better chance of being water insoluble. Phenolic resin (plastic-formaldehyde) in standard grades provide water resistance levels depending on design. It is the same reason you won't find much of a warranty with dust suspended in water or "micro" manufacturing, perhaps Ainsworth is using something similar to that. Pulling vacuum under heat to get voids out of a hydroxide is more labor intensive than pressure injecting wet dust into porous wood and more effective. The way the manufacture processes the materials can have dramatic affects on the leaching of the borate which is inevitable in wet environments, more importantly the toxic heavy metals.
I personally will avoid any chem treats if I can and stick with natural green lumber by not placing it in environments it will fair well in naturally. I'm not interested in a 25 yr warranty or having to fight to get it, or subjecting myself or my home to toxins. I want my homes and my families health to sustain 4 times that at least.
Flitch, I may have to come there and read my posts to you... i never said anything positive about "making homemade PT wood. And I would not use the stuff you use on your orchards. i garden and use no products at all on my garden.
What I advocate is to live IN nature not isolated from it. I also prefer natural products as possible such as using vinegar for many uses.
Flitch, you won't catch me handling Dioxins bare handed knowingly.
I advocate living in nature... natural dirt and bugs and all... not a chemical soup.
And still the word " toxic" is way way overused today. It is the new word of the day.... Everything is bad... NO not true. PT boards are not killing people including most carpenters who never wear gloves to handle unless it is 5 degrees out. Wearing gloves is good. Not wearing gloves is not death.
I just got out of a meeting with our local building association and code officials on this subject. Currently we have no energy code being enforced. They are hiring some consultant firm to come in and educate them on adopting 2012 IECC. Some of these guys never heard the term passivhaus which I brought to their attention as a trend we are in from Germany standards, mainly PHPP and rewriting it. The biggest issue is TOXINS and ventilation rates. Our big box stores are full of them and builders will seal them into new and existing buildings thinking they are getting clients lower energy bills, foam this and that. There is no code or standard out that establishes a relationship between them and ventilation rates, there is none in the PHPP either from what I understand. There are no real regulations or quality checks by state or feds at the manufacture level, they have been caught red handed liing about them to a point the IAQ meters finds higher PPMs than their material data sheets disclosed. The builder, Engineer, has no control in some cases until the home is built and tested, then it is too late, but, they will be the first one the client that dies takes to court. Those are some of the reasons why TOXINs are elevating in concern and that includes house hold products. There are law suits for it, deaths are occurring, we had one here from high levels of CO2. Some, at a young age think it won't kill them, but later in life when the cancer and respiratory problems arise they wonder why? As we build toxic traps it will only get worse. So we enforce air sealing, insulation, etc, and open ourselves up to liability. We can not control what people bring in the home as builders, some good attorney's have already found a way to blame the builder. It is easy to sit out on the internet, not concerned about toxins when you have no skin in the game, other than your own health....I really do not think anyone cares if you have no concern for it, you'll learn the hard way.
My answer is drop the manufacture, take control of them as I build energy efficient air tight homes. You know that blower door test, perhaps several, same is needed for IAQ as you go. I could care less what Germany has done I don't live there. HRV's/ERVs all chem treated can make matters worse, use natural ventilation and heat xchangers, they can be designed into mass or rocket heaters, shades, overhangs, night time flushing, solar reflectors, night time radiation, heat and moisture regulating interior mass in the summer. Moisture can also be added and regulated naturally. I bet the imported HRV-ERV manufactures are loving every sec of the state of confusion we are in the usa, many thinking the answer to toxins is more ventilation instead of not using them in our building materials. If my meter shows a toxin a manufacture did not disclose you can bet it will get reported. Yes, I would say they are big deal in our current industry and trend period! Especially for the designer and his Errors and Omissions liability.
Soon I hope to be the first toxin free "Natural Home" on public display with IAQ test available from a third party. Forget HERS index, RESNET, Energy Star rating's, BS. The word "Green" has become such a toxic misnomer these days I don't use that word in my business model either. My IAQ meter and energy bills are all I need :)
AJ Builder said...."Flitch, you won't catch me handling Dioxins bare handed knowingly. "
AJ have you ever installed vinyl siding? If so, you exposed yourself to Dioxins.
Health symptoms due to materials contact...
http://www.epa.gov/oppfead1/safety/healthcare/handbook/Index1.pdf
Richard, siding guy funerals are rare around here. Sorry to here that it is killing your guys.