Ditto
Marcel:)
Thank you for the warm welcome guys.
Ventilation and a lack of warranty qualification just so happens to be one of my hot buttons.
Since I am not a home inspector, I have not actively posted in this forum, but I like the technical disection of many of the exterior aspects of the building envelope.
I moderate and frequently post on another site called ContractorTalk dot Com and to a lesser degree at JLConline dot com as well. But, it always remains stimulating to find an additional outlet to further expand my data and knowledge resources from.
I added some additional information in my earlier post via a current edit too, referring to some of Marcels valid information.
Ed
P.S. How do I go about getting my User Name changed to Ed The Roofer, which is the name I use on all of the other forums I participate on?
Ed the Roofer,
Welcome.
Wish I could help you in how to change your name, but I am not much of a guru when it comes to computers. ha. ha. I am sure someone will chime in to help you.
Marcel 
It is a VBulletin administrator task. I asked the administrator on the ContractorTalk Dot Com forum where I moderate at, and he told me to email this boards administrator and request it, so I did.
He said it is no problem to do, if someone here actually does read my e-mail.
Ed
Hey Ed,
I didn’t even notice you were a new user…anyway… Welcome aboard! and good post. Like Marcel and Peter clearly pointed out, nothing beats experience.
Actually, I signed up 3 months ago, and posted a couple of times, but my old computers hard drive crashed, and it took me a while to catch up on tasks and importing my Favorites Sites previously bookmarked was not high on the priority list.
Getting Somewhat Back to Topic:
I am compiling a consumers/contractors pro’s and con’s booklet from website sources I can refer to and reference, which will produce a good “Point-CounterPoint” analysis about all exterior factors especially regarding roofing, ventilation, rain carrying systems, and all of the different types of flashings which should be required to be installed on a roof. Residential primarily, but commercial info will be inputted as deemed necessary.
Any links that you could provide would be greatly appreciated. (This winds up being my off season, winter project to compile and edit the articles.) I particularly like actual real world studies, technical reports from manufacturers and the related associations, and white papers.
If you want to store my e-mail address for just such an instance that you come upon something noteworthy, please forward it to
Ed Fako
Right Way Roofing Company
e-mail address: eddiesdad@sbcglobal.net
Thanbk You.
Marcel:
**“Ventilation plays a big role on the life of a roofing shingle, because it overheats and basically cooks and you loose a lot of life.”
**
I’m thinking that virtually no one on these boards have ever had a subscription to the newsletter Energy Design Update or if they had they did not believe what they read. In the July 2006 issue (I believe;can’t find my copy at the moment), a Building Science Corp reseacher measured roof temps of dark roofing materials in Jacksonville, FL during the month of August. Yes, he found that the unvented roofs had higher temps at their surface (the hottest part of the shingle since the sun hits there) but over the month the average temp rise on the unvented roof surface was something like .2 degrees F, not likely to cause shingle failure.
This excerpt from atechnical paper (Ventilation) on the Canadian Roofing Contractors Association is instructive to what’s going on…they speak against the shingle manufacturers and their warranty! practices!!
“The Canadian Asphalt Shingle
Manufacturers Association has issued a
bulletin titled “Proper Ventilation for
Asphalt Shingle Covered Roofs”. In it they
state that both heat and moisture build-up in
attics is the primary cause of many roof
problems including blistering, distortion and
curling of the shingles. It has been
theorized (where’s some proof???..We can theorize forever about anything… ed by BAM) that poor ventilation of attics can
cause excessive heat build-up and high deck
temperatures. Since heat is the major
contributor to the aging of materials, this
heat build-up is said to contribute to the
deterioration of many roof-covering
materials. Although a recent study by
Simpson, Gumpertz & Heger Inc.,
**demonstrated **that geographical location,
building orientation, and roof colour have
far greater influence on roof surface
temperatures than the ventilation below,
inadequate ventilation is often cited as the
reason for roof performance problems.
Material manufacturers may not honour
warranties where it can be shown that there
is insufficient ventilation of the space below
the roof.”
See http://www.roofingcanada.com/techbull/volume53e.pdf
There are some other gems in this paper! Since contractors are a very, very conservative bunch, they don’t go as far as some do in reducing the emphasis on attic ventilation as a solution to many problems. But it was interesting how far they moved the bar into the new building science. It also was interesting at our last quarterly local HI meeting at which one of the largest roofers in our city was the guest presenter. After about 5 minutes of speaking about roof problems relating to condensation, venting, etc, he pointed to myself and said "if you want keep current on this stuff, talk to Brian. That was quite funny to myself since the HI responsible for guest speakers was one I had been arguing on this topic for a few years (but would refuse to read any suggested papers, preferring to talk to some small, back of a 1/2 ton roofers for his info!!)
The above issues have been researched and changes are being made in literature here in Canada.
See http://www.cmhc-schl.gc.ca/en/co/maho/gemare/gemare_001.cfm
I am familiar with and even partially agree with the color and building orientation vs ventilation aspects being debated and providing alternative conclusions than those accepted by the shingle manufacturing industry.
But.
The fact still remains that if the product is not installed per the manufacturers specifications, the warranty validity in regards to related issues of the same, will be placed in peril.
Ed
Brian; good article.
I am well aware of the affects of poor attic ventilation and it’s detrimental affect on roof shingles.
The initial question was double layered roofing approved by Code.
The combination of the double layered roof system and poor ventilation by all means will take half the life span of roof shingles away in a heart beat. Proven, seen and fact. Not very hard to understand when one has spent his life in it’s surroundings.
Your point is well taken and hope that all appreciate our input into this matter.
The problem with today’s Construction World is the fact that everybody does just one thing and do not see the whole panorama picture if you know what I mean.
The guy that does the siding will only do that aspect of the work and install it on whatever and not think twice because he was paid for that particular item only.
The roofer by night will roof your house over another layer and not even question it and I would be surprised if he even read the directions.
The concrete guy, will pour his concrete with complete disregard to the splattering and what effort it will take to clean it up after he is gone.
I could go on and on, but I am sure you get the message.
I am not trying to knock anyone, just trying to make a point of such that people do one aspect of the job and sometimes have no peripheral vision of what is going on.
That is why, we as Home Inspectors get hired to notice these things and be able to intelligently identify the problems caused by such narrow visions.
Every one of you on this post have dedicatedly shown a vision that others may appreciate. And I thank you all for that.
Good job of all of you.
Thanks.
Marcel 
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Marcel, you make an excellent point,
I recently gave a deck presentation to my local chapter, not that anyone new about it, but that another story. Anyway on of my points was when building a new home the framers sometimes install the decks and if your lucky they may use copper flashing where the ledger board meet the house.
Now along come the vinyl siders and they drive aluminum nail through the copper flashing for their siding thus causing a chemical reaction between the copper and aluminum, then the flashing deteriorates within months and the water is now going behind the ledger board and within a year starts rotting out the sheathing then the rim joist.
Huge problem that every inspector should be aware of
Thanks for bringing that up.
The aluminum nail that pierced the copper flashing is lower on the galvanic chart and would chemically break down instead of the copper flashing behind the new siding, fyi.
But, the course of siding material would now lose its hold onto the structure due to the fasteners breaking down. The corrective action would be to advise the usage of copper nails wher they piece through the copper flashings.
Typically, there should not be a difference of greater than .15 in the anodonic chart to prevent galvanic corrosion from occurring.
Ed
Galvanic Corrosion Chart
Galvanic corrosion is the corrosion that results when two dissimilar metals with different potentials are placed in electrical contact in an electrolyte.
A difference in electrical potential exists between the different metals and serves as the driving force for electrical current flow through the corrodant or electrolyte. This current results in corrosion of one of the metals. The larger the potential difference, the greater the probability of galvanic corrosion.
Galvanic corrosion only causes deterioration of one of the metals. The less resistant, active metal becomes the anodic corrosion site. The stronger, more noble metal is cathodic and protected.
Galvanic corrosion potential is a measure of how dissimilar metals will corrode when placed against each other in an assembly. Metals close to one another on the chart generally do not have a strong effect on one another, but the farther apart any two metals are separated, the stronger the corroding effect on the one higher in the table.
This table lists the potential differences for various metals in water. The order of the series can change for different electrolytes (for example, different pH, ions in solution).
I have omitted Stainless steel alloys from this table as they can significantly change their potential and become much more active if exposed to stagnant or poorly aerated water.
Electrode Potential at 77 F (25 C)
Anodic end (this is where the corrosion occurs)
Element
Standard Electrode Potential (Volts)
Lithium-3.045
Potassium-2.920
Sodium-2.712
Magnesium-2.340
Beryllium-1.700
Aluminum-1.670
Manganese-1.050
Zinc-0.762
Chromium-0.744
Iron; Mild Steel -0.440
Cadmium-0.402
Yellow Brass -0.350
50-50 Tin-Lead Solder -0.325
Cobalt-0.277
Nickel-0.250
Tin-0.136
Lead-0.126
Hydrogen reference electrode0.000
Titanium+0.055
Copper+0.340
Mercury+0.789
Silver+0.799
Carbon+0.810
Platinum+1.200
Gold+1.420
Graphite+2.250
Cathodic end, passive - (no corrosion here)
Ed, nice point about all the technical data but the facts remain that deck attachment failure is a direct result of improper fasteners and connectors being used and my point was to bring this subject up to reiterate what Marcel said about one trade not knowing or even caring how their work effects the overall quality of the house being built.
Brian,
If I remember my readings correctly, that paper was written regarding unvented “cathedral or vaulted cieling designs”, which have a completely different trapped air containment than the typical attic structure.
Ed
Brian,
Here is some wonderful archived history regarding where and when ventilation history came from. The 1/300 was a HUD guide from 1942.
Keep throwing links my way too please. I thrive on seeing both sides of the issues.
Ed
Ed:
"Here is some wonderful archived history regarding where and when ventilation history came from. The 1/300 was a HUD guide from 1942."
This presentation is quite interesting since it uses Bill Rose’s presentation materials, is given by Armin Rudd from Building Science Corporation headed by Joe Ltsiburek. Let’s look at these folks 1-by-1.
The Energy Design Update (EDU) article (January 1993) titled The Mysterious Origins of the “1:300” Rule quotes Bill Rose saying it’s origin was from a lab experiment at Penn State performed by Ralph Britton. Now that article was 14 years ago and Rose may have changed his views on this by finding more archived materials. Maybe Britton was testing the numbers in the HUD paper??
Originally Posted by Brian A. MacNeish
I’m thinking that virtually no one on these boards have ever had a subscription to the newsletter Energy Design Update or if they had they did not believe what they read. In the July 2006 issue (I believe; can’t find my copy at the moment), a Building Science Corp reseacher measured roof temps of dark roofing materials in Jacksonville, FL during the month of August. Yes, he found that the unvented roofs had higher temps at their surface (the hottest part of the shingle since the sun hits there) but over the month the average temp rise on the unvented roof surface was something like .2 degrees F, not likely to cause shingle failure.
Armin Rudd, the presenter to the NRCA conference in the web address you give, was the Building Science Corp (BSC) researcher in my above post. I mentioned Joe Lstiburek since he is the principal of BSC. I first met him at a large 1985 building conference titled Avoiding Failures; Learning From Experience in Ottawa, Ontario. From what I know, Joe’s take is that venting does little, if anything, to improve shingle life. He’s the big proponent of the sprayed foam, conditioned attics being used in the “Build America” program where they spray foam right onto the underside of the roof sheathing. This does not allow any ventilation whatsoever and makes sure that virtually all the heat buildup at the shingle surface never gets into the attic. This should be the worst case scenario for having no venting. At least with an unvented regular attic, heat coming through the sheathing can heat the attic air and be radiated down to the insulation or ceiling thus bringing the roof surface temps down a degree or so.
It was interesting to see some of the early assumptions in which air leakeage, the largest mover of moisture into the attic and walls, is given virtually no consideration since they didn’t fully understand all processes/phenomena involved. The emphasis was on vapour barriers and vapour diffusion, missing 98-99% of the problem.
I’ll have to read the presentation more in depth and get back later to start a list of facts/research contrary to the street knowledge on attic venting. May be a few days as from 9:30 AM on 'til Wed morning, I’m fully booked with various items
Brian,
I was hoping to get you back into the discussion relating to the pros and cons about attic ventilation, and for you to have come up with the links that disapeared when your previous posting went haywire and did not allow you to send your lengthy response.
Since our last discussion, I have been adding to and editing my links page into a Word Document in the event anyone wanted a mother load of roofing and ventilation information.
Hope to hear back from you with your response and links if you are not too busy.
Ed
http://www.coolroofs.org/aboutthecrrc.html
History
The Cool Roof Rating Council was created in 1998 to develop accurate and credible methods for evaluating and labeling the solar reflectance and thermal emittance (radiative properties) of roofing products and to disseminate the information to all interested parties.
Mission
The CRRC is incorporated as a non-profit educational organization for the following purposes:
- To implement and communicate fair, accurate, and credible radiative energy performance rating systems for roof surfaces.
- To support research into energy related radiative properties of roofing surfaces, including durability of those properties.
- To provide education and objective support to parties interested in understanding and comparing various roofing options.
Also… Somwhere on BSC I remember reading that ventilating attics is about 5% effective while shingle color can be up to 25% effective for white shingles.