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Old 03-18-2013, 07:28 PM   #16
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Foam VS Fiberglass insulation


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Originally Posted by Windows on Wash View Post
Unfortunately this is not true. R-Value is not R-Value. You never answered my question from before about High Density vs. standard density.

Low density fiberglass batts (those used most often in new construction) are very inclined to suffer from convection and therefore lose a considerable amount of their R-Value.
A parently I was not clear enough I had a contractor give me a bid I had a FG contractor give me a Bid went with the FG R21 in the wall R 13 in the inside walls R 30 in the crawl space R-49 blown under 3 grand done walls sheetrocked taped sanded painted.
Now back to my point
you need to read 16 CFR 460 the FTC states that R-Value is R-value and how manufactures can claim how their product get to that said value. And I sure do hope convection does happen in my home it helps move humidity and air out of the home. http://www.law.cornell.edu/cfr/text/16/460

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Old 03-18-2013, 08:06 PM   #17
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Foam VS Fiberglass insulation


Made this debate its own thread.
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Old 03-18-2013, 09:47 PM   #18
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Foam VS Fiberglass insulation


As posted earlier, the codes (R-values) are simplistic overall requirements to make approvals and inspections and not necessarily accurate. They (code creators) accept materials manufacturers tests on individual products and not how the wall or roof works in the real world (look the other way?).

Manufacturers are great for advertising products themselves and not pointing out end results because they have already run their own assembly testing, but do not have o release the results.

Dick
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Old 03-18-2013, 10:32 PM   #19
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Foam VS Fiberglass insulation


Also, understand that r-value is simply a resistance to heat transfering through the material. It is not the tell all of how a product will perform. Cellulose is the prime example. You get a 3.7-3.8 r-value installing loose fill in an attic flat. However, that value drops down to 3.2-3.5 in a densepacked wall cavity. HOWEVER, even though the thermal bridging will be slightly increased by this, convection is drastically improved. So, that should get rid of the r-value is r-value argument.
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Old 03-19-2013, 07:02 AM   #20
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Foam VS Fiberglass insulation


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Originally Posted by concretemasonry View Post
An "R-value" for a material is not always equal to another "R-value"!!!! There are values for materials themselves, but in many cases the used of the product will only provide 50% to 85% of that value in many cases, depending on the wall or roof construction - whether is a material property and real value in use.

It depends on how it is used. Unfortunately, the building codes are simplistic requirements based on some uses of a material. A prime example is the "R" of a material like a bulk insulating material because it is in a situation between members (like studs and joists) and not as a continuous layer to eliminate thermal short circuits. This is not including the benefits of eliminating air infiltration.

On glaring example of thermal short circulating is the use of 6" fiberglass (R-19) that can give a value 50% less between studs, depending on the spacing and stud material and not solve the infiltration problem.

Dick
+1

Beyond just the thermal bridging issue is also the convection. Air movement in FG = huge drop in thermal performance.

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Originally Posted by RTC_wa View Post
A parently I was not clear enough I had a contractor give me a bid I had a FG contractor give me a Bid went with the FG R21 in the wall R 13 in the inside walls R 30 in the crawl space R-49 blown under 3 grand done walls sheetrocked taped sanded painted.
Now back to my point
you need to read 16 CFR 460 the FTC states that R-Value is R-value and how manufactures can claim how their product get to that said value. And I sure do hope convection does happen in my home it helps move humidity and air out of the home. http://www.law.cornell.edu/cfr/text/16/460
You still did not answer the original inquiry. Did the contractor use high density batts or standard density?

If you do not know or the contractor did not say, they almost certainly used the standard density batting. If that is the case, that wall assembly (regardless of air sealing) will suffer from convective losses and the R-value will not approach the stated numbers except in the mildest of weather conditions.

I think the statement about R-value and the idea that all products with R-x are the same has been addressed.

Quote:
Originally Posted by concretemasonry View Post
As posted earlier, the codes (R-values) are simplistic overall requirements to make approvals and inspections and not necessarily accurate. They (code creators) accept materials manufacturers tests on individual products and not how the wall or roof works in the real world (look the other way?).

Manufacturers are great for advertising products themselves and not pointing out end results because they have already run their own assembly testing, but do not have o release the results.

Dick
Great explanation.
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Old 03-19-2013, 09:58 AM   #21
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Foam VS Fiberglass insulation


and here is the bottom line. I am the coustomer Not you! I pay my power bill Not you! I am happy with what I have and the performance of the product. Not you. The whole thing I was pointing out and I have seen this time and time again. when I have told diffrent contractors No thank you I am using some one else. The seam to get all four point contact sore. and tear down the other products. See I have zero skin in the game. I know how much I paid for my insulation I know how much my heating electric bill is less then 100 dollars per month for a 4,000 square foot home. Been in that home five years. Now non of the loose fill has settled my house is warm in the winter and cool in the summer. so why do you care? I use wood heat 100% I have used most winters less then 2 cords of wood. compaired to my old home what had blown in paper mulch in the attic an God only knows in the walls. I would use eight cords every winter. and my power bill to supplment the wood heat was over 300 dollars, for a 1800 sq foot home. Sorry I look at real savings and how it has performed over time. I am happy with it and do not regret the stuff I had put in. I just wonder why I used so much more wood and electic heat when the attic of my old house said on the cert was R-38 and it was paper mulch? and might have been 15 years old. Would love a real answer to that one not a argument. I have my theory's like the contractor who blew that in there did not do it right. Also I was only in that house while my new one was being built. and I was renting it so I would have up graded the insulation. just so you know. but if you have any thoughts on it I love to hear it.

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Old 03-19-2013, 10:27 AM   #22
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Foam VS Fiberglass insulation


RTC...in reading this post it's becoming pretty clear that you are missing one HUGE factor...labor...You're precious fine homebuilding friend is the watchdog on his jobs and makes sure what needs to be sealed is sealed, etc, etc. What you're missing is that likely 80% of the jobs underway lack that level of oversight. Spray foams and other available systems help to bridge the gap of watch dog g.c. and super lazy g.c. As was said earlier, and clearly needs repeat, foam has a place, as does fiberglass, as does cellulose. To say fiberglass is the only insulation to be used is very shortsighted and is a statement lacking a true understanding of the building industry, for better and for worse, because I have clients who could care less about fine homebuilding magazine or blower doors...
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Old 03-19-2013, 10:33 AM   #23
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Foam VS Fiberglass insulation


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I just wonder why I used so much more wood and electic heat when the attic of my old house said on the cert was R-38 and it was paper mulch? and might have been 15 years old. Would love a real answer to that one not a argument.
The house isn't sealed right...so, mr. fiberglass, how do you propose to properly seal an existing house? This is where the caulking gun charges start to rival spray foam charges...see the bigger picture now?
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Old 03-19-2013, 10:35 AM   #24
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Foam VS Fiberglass insulation


RTC -

Why get in such a snit?

Your original post a sketch at best had n real details. Later posts indicate you had many other conditions that were not initially presented, but dropped in later to draw things out. Your replies indicate you have made significant independent searches and did not agree with the your research. - Just use your independent research results since you know the actual conditions.

To get good opinions, you have to ask good questions and provide complete information of the conditions. This is actually a U.S. based forum that can also address unique international situations if the conditions are provided.

When you arbitrarily cite other research references, you must realize they are for specific materials in specific application that will not agree with the real world. It is all about taking all the the pieces and put them together to come up with a solution for the situation.

Dick

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