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Icynene,Ventalation and mold/Mildew


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Inspected house built in 1920’s that have been updated in 1999. Many of the 2nd floor windows {installed in 1999} have mold/mildew. The house attic has an air handler in the attic; system was operating okay, although the filter was dirty. The attic sheathing and walls is totally covered with this insulation which I have never seen before. I believe it is "Icynene Insulation System" I always thought attic should have ventilation. The roof has a ridge and soffit vent's but with this product it appears useless. My understanding is the house is not used much. The owner was last there in July 2005. Could this foam insulation product be causing the mold/mildew on the windows? Can this be good for roof shingles,attic sheathing and could this be the cause of the mold on the windows?

Thanks

John Callan [?]

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Hi,

When you touched that foam was it soft and pliable to the touch or was it hard on the surface and scabbed over? It looks like it might be closed-cell foam, in which case, unlike Icynene, it won't allow the house to breath as well.

That said, if the home stays vacant most of the time and isn't being aired out, you can expect moisture to collect at colder areas around window and door casings and once it takes hold it will simply continue to propagate until cleaned up.

If it's vacant most of the time, it would make sense to have a properly-sized dehumidifier or air exchanger installed that is controlled by a humidistat and set to automatically dry the house whenever it exceeds 46% RH.

My opinion. Worth price charged.

ONE TEAM - ONE FIGHT!!!

Mike

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Even if it is polyurethane (or icynene) the insulation isn't responsible for high moisture contents in a vacant home. It's most proably as Cramer described, but it may be prudent to check furnace/boiler venting if the house was heated through the winter.

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Thanks guys for the quick response,that answers my window question. But what about this type of insulation in the attic sheathing and walls is thss good for the roof? As I said in my previous post there is a ridge vent which would appear to be useless at this point. I always thought attic's suppose to have ventilation? Will this effect the sheathing and life of the shingles? Why have a ridge vent with this.Again I have never seen this in attic's before.

John Callan

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I believe that the mold on the window frames is caused by humidity/moisture. Primarily from condensation on the glass, especially since they are single pane. As Chad noted, there could be other causes adding to the problem.

I strongly agree that additional venting/air exchange for the space itself is necessary.

It's hard to tell from the picture, but the way that the foam is somewhat concaved alongside each and every rafter, I am guessing that "Raftermates", or similar product was installed prior to the application of the foam. In which case, an air passageway is still present. This would enable air flow/exchange from the eaves to the ridgevent, below the roof sheathing... a good thing.

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Looks like Icynene to me.

Traditional thinking has always been "the more attic ventilation the better". This concept is consistent with "let's design and build all houses the same without regard to the climate in which they have to function". Recent thinking among building scientists, Dr. Joe included, seems to be shifting to designing homes with sealed, or closed, attics in hot humid climates.

Makes sense to me. Why would you want to ventilate an attic in a home here in S. Florida with moisture laden air? The outdoor RH down here in the summer is often well into the 90% range. These high levels are even more consistent where high end homes are built on waterfront lots.

OK let's look at what we are doing when we ventilate an attic in such a climate. Moisture migrates from areas of high moisture to areas of lower moisture. Outside to inside. We fill the attic with wet air, the A/C cools the conditioned and sometimes the attic side of the ceiling drywall to below the dewpoint. Vapor in the attic air becomes a solid (water) and condenses on the sheetrock, recessed light fixtures, smoke alarms, A/C supply and return diffusers and any other ceiling perforation. Eventually mold forms on the building components. It's a constant self propagating cycle.

Recently I inspected a multi-million dollar home on the intracoastal waterway. The owners complained of a strong mildew odor in the home. The thermostats for all four central A/Cs were set for 70 degrees in the cooling cycle. One of the attic accesses was located in the master bedroom walk-in closet. Mirrored bifold doors were installed at the closet entry and there was a dresser with a mirror in the closet. As soon as I opened the attic hatch the glass surfaces fogged over as the wet air in the attic moved to a location of lower humidity, the conditioned area of the home below. I suggested the owners retain a mechanical engineer in order to explore retrofitting the house with a closed attic and possibly supplemental dehumidification of the attic space. The A/C systems may have to be redesigned since the attic now becomes semi-conditioned space.

Testing has proven that a sealed attic doesn't raise the temperature of the roofing materials to a point which shortens their servicable life nor does it affect the manufacturers warranty. Hopefully, within the next couple of months I'll complete one of my many unfinished projects which is an article titled "Menopause Money and Mold" which deals with, among other concepts, how lowering the temperature below 74 degrees can cause the relative humidity within a space to rise exponentially.

Well, that's my thoughts in thirty words or less.

NORM SAGE

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Windows are not single pane. I don't think their was any product or passageway such as raftermate installed prior to installation.In my opinion I think this attic has major ventilation issues. Unless someone illuminates me differently.[:-magnify

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I wasn't there, thought I saw single pane glass in the pics. Agree about ventilation. No raftermates, o.k. I'm curious as to what gave the foam that distinctive shape?

Hey Joe,

How's Florida? Living in N.Y., and noting the house in the picture was from Maine, what you brought up never entered my mind. But, I agree, questions, answers and solutions change with the environment.

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Originally posted by Norm

Testing has proven that a sealed attic doesn't raise the temperature of the roofing materials to a point which shortens their servicable life nor does it affect the manufacturers warranty. Hopefully, within the next couple of months I'll complete one of my many unfinished projects which is an article titled "Menopause Money and Mold" which deals with, among other concepts, how lowering the temperature below 74 degrees can cause the relative humidity within a space to rise exponentially.

Well, that's my thoughts in thirty words or less.

NORM SAGE

Norm I inspected a 7 year old home a few years back and the roof shingles were cooked and destroyed. As it turned out there was no ventilation of any kind installed. The attic was standard construction.

It is my understanding that a sealed attic system must be constructed differently than standard construction with insulation on the ceiling of the attic.

As this is a relatively new concept does anyone know the details of this system.

Thanks,

Paul B.

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Although the possibility is remote, I have seen homes that had similar issues due to an over sized cooling system that was de-heating so fast that it simply wasn't de-humidifying.

Whenever I see conditions like this it's certainly on my list of considerations.

I have seen three new construction homes with completely sealed attics. While I'm a huge fan of sealed crawlspaces and was long before it was even fashionable, I'm a bit skeptical about sealed attics and roof life.

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I recently built a house where the attic space is being used as living space, besides adaquate ventilation in the area itself, Raftermates and insulation, along with ridge and eave venting was built in prior to finishing the undersides of the rafters.

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Originally posted by JohnC

Thanks guys for the quick response,that answers my window question. But what about this type of insulation in the attic sheathing and walls is thss good for the roof? As I said in my previous post there is a ridge vent which would appear to be useless at this point. I always thought attic's suppose to have ventilation? Will this effect the sheathing and life of the shingles? Why have a ridge vent with this.Again I have never seen this in attic's before.

John Callan

It's hard to get your head around this concept, but try thinking about it like this. When you insulate the underside of the roof, you make the attic part of the conditioned space. It doesn't need ventilation any more than the wall below it does. It's now just like an insulated wall turned on it's side.

As for the shingles, research done here in FL indicates that the temperature of shingles over unventilated attics is no more than 5 degrees higher than the temperature of the shingles on a ventilated attic. It's an insignificant difference.

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  • 3 months later...
Originally posted by JohnC

Inspected house built in 1920’s that have been updated in 1999. Many of the 2nd floor windows {installed in 1999} have mold/mildew. The house attic has an air handler in the attic; system was operating okay, although the filter was dirty. The attic sheathing and walls is totally covered with this insulation which I have never seen before. I believe it is "Icynene Insulation System" I always thought attic should have ventilation. The roof has a ridge and soffit vent's but with this product it appears useless. My understanding is the house is not used much. The owner was last there in July 2005. Could this foam insulation product be causing the mold/mildew on the windows? Can this be good for roof shingles,attic sheathing and could this be the cause of the mold on the windows?

Thanks

John Callan [?]

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In regards to the question of what about the shingles when the iceneing foam is applied directly to the bottom of the roof deck. There is only one shingle manufactor in the entire US that will offer any warrenty, that in itself must tell you something. After 40 years of building, I highly recommend having a 1" airspace under the roof deck which is easily done by using the Corwin smart ventilation system. Can be used even in a retrofit. Write to tomceejay@aol.com for more information. Web site coming soon.

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Originally posted by tomceejay

To answer Jim of Oregon's Question, the reason is that without any ventilation under the roof deck, the shingles bake and crystallized. Much like laying on the black tarmac on a hot day as apposed to laying on a lawn chair with air flowing under you. Tom

There's no science to back up that statement. Every study and experiment that's been made on the subject refutes your conclusion.

- Jim Katen, Oregon

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Yup. Ventilation does little to reduce shingle temperature. Mfg's. put in the disclaimer just like they tell us that anyone walking on a roof voids the warranty.

Excessive shingle temp is about orientation & shingle color.

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