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foam insulations


billygoat22
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Has anyone seen the urethane and icyrene foams in use out there? I think they would give good performance and would like to share with people the option of using these products in their homes, since you can buy smaller a/c and lower bills with insulation upgrades.

Especially commercial buildings. We'll be doing some this summer and insulating the roof sheathing with icyrene would give a semiconditioned attic and better air sealing of building. Drop ceilings and the batts stapled in place just don't cut it.

How about urethane on ductwork? Maunfacturer says ok, but local inspector has toapprove, of course. Thanks.

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Bryan,

I used foam insulation when I built my last house. The R-value is superior and the skin it forms acted like a vapor barrier. I didn't even try to insulate any ductwork (basement) The only problem is being careful around window and door framing.

The directions are clear, and I did pretty well except on my garage back entrance door. I put in too much and warped the door frame enough that it closes very hard.

Gloves, old clothes, old shoes and eye protection are a must. This crap is STICKY

George

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Sheathing would be the plywood skin on a house wall or roof. I've heard of icyrene being used because the underside of roof rarely has anything penetrating or attached to it. This would allow the install of mech. systems witout disturbing the insulation.

Being an open cell foam it would allow water leaks to pass through the material, rather than hidiing a leak and rotting the sheathing.

I have seen the urethane on ducts and walls, tough stuff, and seals the envelope. Just wondering if there are any negative sides to this product.

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Originally posted by a46geo

Insulating the under side of shingles would certainly shorten their life. Would it void any factory warranty?

George

That's a common misconception. Recent research shows that if you eliminate ventilation of the attic, it increases the surface temperature of the roof by 2-3 degrees.

Many of our code requirements are based on "that's the way we always do it" rather than knowledge derived from research.

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Originally posted by mcramer

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Many of our code requirements are based on "that's the way we always do it" rather than knowledge derived from research.

Or, if you're in Chicago, the codes are based on what Mikey down @ inspection services says rather than derived from intelligent thought. Or, what will protect & enhance union employment, rather than what benefits consumers.

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Placing insulation underneath the roof sheathing will have a negative effect on the roofing material. It would not only void any guarantee but place the envelope at risk of moisture deterioration.

Air, vapour and moisture barrier location and VENTILATION must be considered in the design mix for the system to work properly.

Here is something that may apply to your part of the world that typifies good construction detailing regarding ventilation and the prevention of ice daming.

Download Attachment: icon_photo.gif VentilationNIceDam_M.JPG

99.94 KB

I can't locate the perm rating for the insulation in question, if anybody out there has that information it would be useful in the discussion.

Mark,

Maybe you could point me to the research your'e referring to.

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Those were the issues I was concerned about. In Va this would be a "mixed" climate- about equal hours of heating and cooling. Unless the weather gets real extreme(for here) you don't hear much about ice damming.

The insulation does affect the roof, up to 5% if I recall correctly, but this would only apply to fiberglas/asphalt products? The icynene people state their product has a pretty high permability, which would help prevent moisture trapped in building assemblies.

Urethane has a much lower perm rating, even so, they recommended a butyl coating on their product when used as a duct insulation.

I'll have to check with the shingle manufacturer to see what thier take on warranty is. Even if the roof life was reduced, bringing attic a/c and heat equipment into the conditioned area would reduce sysytem size 10%, and there would be the reduced air infiltration gains also.

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Icynene: Not a Vapor Retarder. According to the Alaska Craftsman Home Program, polyicynene insulation is a good insulator but fails as a vapor retarder. While vapor retarder materials must have perm ratings below 1, 5 inches of Icynene Insealation has a perm rating of 10. The foam is able to resist moisture penetration when a house is under neutral pressure, but moisture is able to pass through the foam with the help of differential vapor pressures. Thus, standard moisture control methods, meaning those used with fiberglass insulation, are recommended when installing polyicynene. Northern Building Science, Sept/Oct 1996. Alaska Craftsman Home Program, Incorporated, 900 West Fireweed Ln., Suite 201, Anchorage, AK 99503-2509.

That Fabry guy is full of crap. Perm of 10, icynene should not be used as a vapor barrier. Wonder where he read that it could be used.

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Hi All,

Mind if a delusional inspector takes part in this thread?

Chad,

Water moves pretty readily through icynene and it's permeability allows it to dry out completely as well. Closed-cell foam is an entirely different matter. Those can trap water against a roof. One of the contractors who visited my forum at JLC a couple of years ago had to completely strip off all of the sprayed-on foam, reinsulate and replace portions of a steel roof on a large commercial building, because it was badly rusted due to water being trapped above a layer of sprayed-on closed-cell foam.

Rob,

It is true that some manufacturers won't honor their warranty if the underside of the roof is sprayed, but more and more are recognizing that heat isn't so much the enemy of the roof system as moisture buildup in the shingle media is. It is relatively common in some parts of the country to see icynene used on the underside of roofs. Some builders using it get around the manufacturer's ventilation requirement by using vented nail base insulation, while getting a higher R-value roof, others use a double membrane, venting the deck while turning the attic space below it into a conditioned space.

The construction industry is slowly recognizing that a lot of the rules and assumptions involving vapor transmission, heat and cold that they've been living with for decades are flawed - many seriously - so they're trying to catch up. The problems that are being found with these 'new' ideas stem more from installer error than they do from flawed conception. In their rush to get with the program many builders are omitting critical steps. When problems develop, building officials catch the heat, so they become reluctant to allow new technologies and the old flawed ideas continue to be perpetuated.

Brian,

Spend an afternoon and a pot of coffee checking out some of Dr's Lstiburek and Yost's work at Building Science Corporation's site and then follow some of their links. Keep in mind that some of Joe L's ideas are cutting edge while others are just old science reemphasized, and that anything you do will require a complete understanding of how insulating that roof plane will affect other systems.

ONE TEAM - ONE FIGHT!!!

Mike

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Bryan,

You make a good point. Here in Michigan the vast majority of our air handling and distribution systems are installed in basement areas (conditioned space). That removes a lot if issues and sizing problems found in attic installations.

If it adds fewer problems than it solves, it may be worth a good look.

George

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Hausdoc, I have building Science corp on the favorite links on my computer. I also have Several of his books,Moisture Control Handbook and Builder's guide to mixed Climates. I've come across that name and his organization a number of times.

Much of what I've read into and the books I've got have been driven by problems I've seen in the field. In some cases I added upgrades to my work to sovle problems with the install I replaced, then later found a manufacturer or some other source that promoted what I had employed at work.

There's an article in Contracting Business online titled "13 seer, oh really". It addresses a concern I had noted and hope to address by pushing for better hvac duct insulation and sealing, as well as the house envelope.

Old habits are hard to break, I've been trying for three years to get the foam insulation thing with the duct started. [:-banghead]

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I can see a lenghty debate over the ventilation issue.

In the real world of constuction, vapour, weather, and air barriers are never perfect hence you will NEVER find those components operating in absolute values. They both share numerous penetrations that compromise their integrity, and in short, ventilation must be included in the equation to keep the forces of mother nature in balance.

Mike,

"venting the deck while turning the attic space below it into a conditioned space."

That concept would be called converting rafters into ceiling joists and the rules of ventilation apply here as well.

I would obtain an endorsment from the AHJ before proceeding in unknown territory.

Enclosing a system and expecting it to work according to one's calculations is risky business in my view.

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RobC wrote:

That concept would be called converting rafters into ceiling joists and the rules of ventilation apply here as well.
Well, it's not as simple as that. The AHJ may force one to ventilate the ceiling plane, but it's a simple fact that, if the ceiling/roof plane is sealed correctly and moisture can't get into it, ventilation isn't necessary. Some AHJ's will let you get away without ventilating it, if you prove to them that what you're going to do will work.

How often does that happen? Almost never. Very few builders take the time to try and reach that degree of air sealing, although Fred Lugano has had excellent success doing just that in Vermont by dense-packing cells into cathedral ceilings and sealing the ceiling plane completely.

ONE TEAM - ONE FIGHT!!!

Mike

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I read ya Mike,

I'll bet Fred Lugano supervises every square inch of his installations and he may be successful at it but he's the exception.

My concern is vapour transmission through the vapour barrier penetration points that will eventually cause the damage.

As a renovator, I've see lots of failures due to incorrect or lack of ventilation in wall, ceiling construction.

I see theory butting heads with general construction practices here, kind of reminds me of the EIFS fiasco a few years ago, close to your location.

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"Sealing the ceiling plane completely". I still don't get how this works, although I've been involved in the process.

It is still a building constructed of wood, drywall, sheathing, etc. There will be atmospheric change. Building materials will attempt to equalize to those changing conditions. Over time, there has to be some atmospheric/moisture content changes in those materials, no?

It will never enter the building industry vernacular as it requires thought and meticulous practices. One can see why foam is so popular; point the gun, pull the trigger, voila. Insulation, w/out all the thorny issues of venting, at least not yet anyway.

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Quite an interesting topic gentlemen. I wish I understood it better.

Kurt said, "Over time, there has to be some atmospheric/moisture content changes in those materials, no?"

Makes sense to me, moisture will eventually enter whatever envelope we try to seal. Wood is a porous material, glass on the other hand is not, how many failed seals on dual glazed windows have you seen?

Ron

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