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Old 02-07-2012, 03:49 PM   #16
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Spray Foam vs. Fiberglass, anyone done the math?


AG: The future, no doubt about it. It will likely be in codes more and more, which means we'll have to do something to clean up the AIR in some places. That will be an interesting dilema; do we require ventilation in houses if the air outside the house is worse than inside? This is from Martin Holladay on greenbuildingadvisor.com, back in March of '12. "....this HRV has a sensible heat-recovery efficiency ranging from 64% at -13F to 75% at 32F at 49 cfm." See if your uncle has more data, like efficiency at what temps, etc. 95% would be incredible. NEFoamer: 40-50% over WHAT?

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Old 02-07-2012, 04:19 PM   #17
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Spray Foam vs. Fiberglass, anyone done the math?


What is the OP asking about?? Foam will perform 40-50% better than filterglass, that's for sure. Even during "perfect" installation it does not perform to rated R-value. Independent studies have said that typical installation results in around 25% loss of it's r-value. Foam certainly isn't the end all, be all, but it's a great product and the people who pay 3x more for it understand the value.

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Old 02-07-2012, 04:51 PM   #18
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Spray Foam vs. Fiberglass, anyone done the math?


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Foam will perform 40-50% better than filterglass, that's for sure.
Oh. OK. No doubt about foam being far superior to fg batts.
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Old 02-08-2012, 04:24 AM   #19
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Spray Foam vs. Fiberglass, anyone done the math?


I just fell out of my chair...40-50% savings...?
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Old 02-08-2012, 10:20 AM   #20
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Spray Foam vs. Fiberglass, anyone done the math?


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Originally Posted by NEFoamer View Post
Here is one case study, I'm sure you can find some more out there, hopefully more specific to your location.

http://advancedinsulationla.com/casestudy.pdf
Looks like you didn't air seal the FG house. That report is like comparing the thermal efficiency of a storm door with gasketing and one without. Of course the leaky one will perform worse... But it's a perfect marketing tool for a spray foam contractor. "Here gullible home owner, see!"

Lets be clear though, foam will perform better than FG, but it won't perform THAT MUCH better if the FG home had been air sealed properly.

In 25 years, when the foam degrades, how will you repair it? You can't just take it out like FG, you have to chip/scrape/cut it out which = $$$. The sustainability of spray foams is deplorable...
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Old 02-08-2012, 01:38 PM   #21
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Spray Foam vs. Fiberglass, anyone done the math?


Go with the spray foam!

Why?

1: You save up to 50% on heating and cooling costs over conventional insulation. Spray foam also creates an air barrier which cannot be achieved with batt insulation because of the seams. It doesn't lose R value in cold or wind las does any type of batt insulation, and when fiberglass in particular gets wet from any leaks its R value is rendered useless.

You can realize a real world profit of 74% per month on your utility bills over fiberglass insulation. The added cost to your mortgage of spray foam to an average home is about $20.80/mth. But this average home saves $88 on HVOC costs per month! Energy costs will only go up and in the 30 years of your mortgage the savings will only increase = money in your pocket and reducing your carbon footprint.

2: You save by being able to install smaller furnaces and air conditioning units.

3: You save by being able to use 2X4 studs instead of 2X6 studs during construction of your house.

4: You save by not needing interior and exterior vapor barrier during construction as spray foam is also a vapor barrier if 3 inches thick or more.

5: Installation costs of spray foam is also cheaper than fiberglass or other batt insulation.

Sources:
http://www.ecologicinsulation.com/Questions.html
http://kinlar.ca/residential.aspx
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Old 02-08-2012, 01:41 PM   #22
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Spray Foam vs. Fiberglass, anyone done the math?


Go with the spray foam!

Why?

1: You save up to 50% on heating and cooling costs over conventional insulation. Spray foam also creates an air barrier which cannot be achieved with batt insulation because of the seams. It doesn't lose R value in cold or wind las does any type of batt insulation, and when fiberglass in particular gets wet from any leaks its R value is rendered useless.

You can realize a real world profit of 74% per month on your utility bills over fiberglass insulation. The added cost to your mortgage of spray foam to an average home is about $20.80/mth. But this average home saves $88 on HVOC costs per month! Energy costs will only go up and in the 30 years of your mortgage the savings will only increase = money in your pocket and reducing your carbon footprint.

2: You save by being able to install smaller furnaces and air conditioning units.

3: You save by being able to use 2X4 studs instead of 2X6 studs during construction of your house.

4: You save by not needing interior and exterior vapor barrier during construction as spray foam is also a vapor barrier if 3 inches thick or more.

5: The labor cost of installing spray foam is also cheaper than fiberglass or other batt insulation.

Sources:
http://www.ecologicinsulation.com/Questions.html
http://kinlar.ca/residential.aspx
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Old 02-08-2012, 01:44 PM   #23
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Spray Foam vs. Fiberglass, anyone done the math?


here is a place to start in Vermont. the instructor with the answer is sourced for you

www.yestermorrow.org/instructors/view/96
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Old 02-08-2012, 02:02 PM   #24
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Spray Foam vs. Fiberglass, anyone done the math?


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here is a place to start in Vermont. the instructor with the answer is sourced for you

www.yestermorrow.org/instructors/view/96
Riversong knows his stink, too. Very knowledgeable individual. He has contributed on a variety of forums and blogs as well, and is one of the builders who is focused on us minimizing our negative impact on the world.
Anglii: You must work for a foam company. I read a little hyperbole in your comments, and some are true no matter what you insulate w/ (needing smaller boiler, etc). If one really wants to build cheap ($/R), far less expensively than spray foam, be able to super-insulate, be environmentally friendly, ward off bugs and rodents, etc, then build a double stud wall w/ dense packed cellulose. Spray foam has its place, but not in my place; way too expensive and torturous to the environment. To me, its a last-resort product to be used sparingly. Good stuff, just don't get carried away w/ it.
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Old 02-08-2012, 02:20 PM   #25
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Spray Foam vs. Fiberglass, anyone done the math?


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Lets be clear though, foam will perform better than FG, but it won't perform THAT MUCH better if the FG home had been air sealed properly. . .

In 25 years, when the foam degrades, how will you repair it? You can't just take it out like FG, you have to chip/scrape/cut it out which = $$$. The sustainability of spray foams is deplorable...
.

Studies show you cannot achieve the same kind of air seal with batt insulation and the real world R-value of batt is decreased depending on the environmental temperature and wind speed. I.E. "R-13 fiberglass batt in the presence of a 10 mile per hour breeze diminishes the insulating power of a batt to an R-5".

Where did you get your information that spray foam degrades? Because if parts A and B are mixed properly it is inert and does not degrade after it has cured (in about 4 hours).

But you do have to get an experienced installer to make sure it cures properly. Some risks include allergy to the petrochemicals used. But staying away from the building site until it's cured and looking at soy based options would prevent sensitization.

http://www.greenbuildingadvisor.com/...oisonous-fumes
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Old 02-08-2012, 02:41 PM   #26
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Spray Foam vs. Fiberglass, anyone done the math?


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Looks like you didn't air seal the FG house. That report is like comparing the thermal efficiency of a storm door with gasketing and one without. Of course the leaky one will perform worse... But it's a perfect marketing tool for a spray foam contractor. "Here gullible home owner, see!"

Lets be clear though, foam will perform better than FG, but it won't perform THAT MUCH better if the FG home had been air sealed properly.

In 25 years, when the foam degrades, how will you repair it? You can't just take it out like FG, you have to chip/scrape/cut it out which = $$$. The sustainability of spray foams is deplorable...
Deplorable??? Please. Show me some examples of closed cell spray polyurethane foam degrading in an interior wall. Spray foam has been around since the 50's so I'm sure you can find plenty of examples. The only thing that will deteriorate foam is direct exposure to sunlight.

As far as the case study goes, I didn't forget to do anything as this was done by the Habitat for Humanity. I don't know what was or wasn't done as far as air sealing goes. You can use all the caulk you want and spray foam will still do a better job. Hence the fact tens of thousands of people use it every year.
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Old 02-08-2012, 02:59 PM   #27
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Spray Foam vs. Fiberglass, anyone done the math?


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Deplorable??? Please. Show me some examples of closed cell spray polyurethane foam degrading in an interior wall. Spray foam has been around since the 50's so I'm sure you can find plenty of examples. The only thing that will deteriorate foam is direct exposure to sunlight.

As far as the case study goes, I didn't forget to do anything as this was done by the Habitat for Humanity. I don't know what was or wasn't done as far as air sealing goes. You can use all the caulk you want and spray foam will still do a better job. Hence the fact tens of thousands of people use it every year.

Come visit my house I will show you foam disintegration after use in my walls since the 70's.

I am wondering if they have ever come out with a true R value for foam as off gassing continues for years after installation.

Now my private concerns with site foam blowing has to do with the mixing on site without precise computer control of the mixing agents which will give foam site blowing different than factory foam.
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Old 02-08-2012, 03:27 PM   #28
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Spray Foam vs. Fiberglass, anyone done the math?


Yes...Deplorable...current foams are made from oil. Being that oil IS finite and being consumed a mind boggling rate, it's safe to say an end WILL eventually come. The essence of sustainability is a product that is "natural" and therefore can be found readily available through the existence of earth (barring no apacolypse of course).

And thank you framer for the rea-world example. Foam degrades people...sorry to burst the "cure all" sentiment. Most rigid foam manufacturer's don't warranty their products for more than 20 years. And most pro-rate the R-value to accommodate the degredation over the lifetime. Polyiso, when blown, is around R-7+ an inch, but they advertise around R-6.5 an inch to account from degredation.
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Old 02-08-2012, 03:32 PM   #29
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Old 02-08-2012, 03:50 PM   #30
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Spray Foam vs. Fiberglass, anyone done the math?


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.Where did you get your information that spray foam degrades?
Here's one manufacturer noting the degredation of their polyiso foam: http://www.hpanels.com/images/storie...h/H-Shield.pdf

Notice on the Thermal values chart the asterisk next to "LTTR R VALUE" and the sentence below. The "weighted average" is the technical jargon to account for foam degredation over a 15 year period. Essentially if the foam is an R-7.5 when new and assuming constant degredation it would be approx. R-4.6 after 15 years making the average the R-6.0 as depicted.

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