Has anyone seen any horror shows with this application. Builder said that a barrier was stapled into the rafter bays to keep the foam from expanding through the gaps between shingles but not sure if there is a preferred method. It would seen to me that no matter what, moisture will be penetrating to the top of the foam.

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Thats a mess in the works. Did you get the phone # of the contractor the put that up.


Best

Ron

Yes I did, and it's not in the works. It's done. 1.5 years done.

You're most likely right Wayne
moisture will be penetrating to the top of the foam, and
water damage could be concealed for a considerable
amount of time.

Wayne, I know it's late with the information, and the report is history, but here is some info for the future. (Building Science Digest 149)

Note the installation instructions for wood shingles or shakes on pg. 6. I am not sure if this is what the contractor described?

One way to identify open cell from closed cell is the resistance to denting with slight pressure of the thumb. Open cell is very easy to dent.

Leaks in the roofing, seep through the open cell foam and make locating the source easier to find. Closed cell is a different story!


www.buildingscience.com/.../bsd-149-unvented-roof-assemblies-for-all-climates/2007-07-

Yes, Vern, Open cell foam at this location. Did all the homework. The leak detection is much better and the foam will dry. No r factor till dry but will dry. I told them to call you if they had any. HAHA

Vern

Your link is not fully complete. Can't find the info.

Thanks,

__________________

operable link

BSD-149: Unvented Roof Assemblies for All Climates —

__________________
Jerry Peck, Construction / Litigation Consultant
Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )

Thanks Jerry.

Also I found this statement interesting:

That's great, but if its leaking and the damage is contained, you still aren't going to find out about the leak for possibly quite some time.

Putting foam on the back of wood shingles is not going to allow them to breath, likely cutting the life expectancy in half or more in my opinion. The whole purpose of the lathing is to permit ventilation, the foam would seem to defeat the lathing. Personally speaking its not something I would do on a wood shingle roof.

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Did you read the part about putting it under wood shingles?

6 millimeter = 0.236 220 472 44 inch or 1/4" (between 7/32" and 1/4")

I know ... but what about when the foam is applied after the wood shingles and shakes are already there?

__________________
Jerry Peck, Construction / Litigation Consultant
Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )

In this case a breathable barrier was installed to prevent the foam from adhereing to the shingles and allow water to pass through if leaks occur.
Heard it from the horse.

There is going to be a lot of wet wood.

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Measured Performance more than just a buzzword

Wayne - for what this is worth...

I have had very little experience with the new "green" ventless roofs here in Virginia. I have done lots of reading (Building Science and so forth) and am generally skeptical about all the "green" stuff being thrown around, and I mean all of it. To me, green means mo' money and mo' gubment control, but that is me.

However, I had a gentleman call me the other day with condensation problems throughout his house. He proudly informed me that he had a ventless roof - three years now. Looking inside the attic looks very much like your photo. Until this thread, in my readings, I had not come across the closed cell and open cell foam criteria, so I don't know what he had. But he did have molds everywhere and did not know the cause. My gut diagnosis then, prior to my readings, was the lack of ventilation throughout the roof.

In my readings I understand that in humid climates the foam should not be used, in favor of a cellulose instead. One of my building science links states that when humidity gets above 40% it presents problems with moisture being held inside the wood (framing, sheathing and, in your case, shakes) as there is no where for it to go. This reminds me of undrained EIFS and recently the problems associated with the faux stone sidings.

Theorectically I know wood will not rot without one of three things - air, food and water. How foaming a roof prevents moisture, via humidity, from getting into and then not conveniently out of wood is beyond my current understanding. When I said this to my client with the mold problem he poo-pooed me saying that soon all houses will be built this is the new wave,"way of the future," and I need to get with it! Okay then! So, smart guy, why is your whole house molding?

Wayne, you say this is 1.5 years old - any molds? Untoward condensation? Moisture retention? As an inspector, I am very interested in this "new wave." Lemmino!!

This is what "green building" means to me:

- cheaper materials (uses fewer trees)

- fewer materials (uses even fewer trees)

- less labor (fewer man hours needed with fewer trees needed)

- less energy used in construction (during manufacture of the materials and the installation of the materials)

- workers make less, so they must faster on more jobs to make the same money, which makes for low quality work

- nice big signs which state "This is a Green Building."

- much chest beating by builders

- big smiles by clients who think 'That is a good thing.'

- yet, for some unknown reason, all that "saved" money does not lower the cost of the house, in fact, the cost just went up "Sure, it costs more" says the builder "but it is better for the environment. That is a good thing for all of us."

- they buyer thinks "Okay, that IS a good thing."

- builder smiles and walks away, with pocketfuls of extra money, thinking "Well, it does help me. Now I can go buy that ... I've always wanted. AND THAT helps everyone else."

__________________
Jerry Peck, Construction / Litigation Consultant
Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )

Like I said, mo' money, mo' gubment control.

But what about the moisture? That is my real interest here...

Just because the guy has a foamed roof it does not mean that is the source of his condensation issues.
There have been many moisture related issues with vented attics as well.
Was the moisture prevalent in the attic or other areas of the home?

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Measured Performance more than just a buzzword

There were no moisture issues. Just wanted some input. got alot of that.
Now the post has turned into a sales pitch for that Green stuff.
Not "That" green stuff Barry

Looks fine to me... Ron... mess? I just did a spray no vent roof. The home has no problems and uses far less fuel to heat.

adkjac

others... mold.. look for water source and cold air leaks. Cooks that don't use pot covers and fans, showering without fans, lots of plants watered daily, cellar, crawspace lacking vapor barrier. humidifier running way to much.

One of the things that happens when you have a conditioned attic is the HVAC unit has to be down sized to compensate for the additional "tightness" of the structure. If the HVAC contractor just figured in the space that he was cooling and sized it to that then the HVAC unit would not cycle long enough to take out the humidity. That's why you down size! The unit must run longer to remove the humidity from the structure.

Sounds like the guy with the mold problem might have too much AC.....amongst other things mentioned.

Not necessarily.

You are are effectively adding the entire attic to the area (cubic feet of space) which much now be 'conditioned'.

One cannot say that the AC must be downsized because of the greater tightness anymore than one can say that the AC must be upsized because of the greater cubic feet of air being handled.

In both cases (insulation on the ceiling and insulation on the underside of the roof sheathing) all top plates *are supposed to be* draftstopped/firestopped - which means "sealed" (with the appropriate materials and methods).

__________________
Jerry Peck, Construction / Litigation Consultant
Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )