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reflective insulation

Posted by greif (My Page) on
Tue, Nov 20, 07 at 20:22

does the reflective insulation (mylar/ metalized) need an air gap to reflect heat back?

thanks
gary


Follow-Up Postings:

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RE: reflective insulation

Yes --The reflective (aluminum) coating has no beneficial effect unless it has an air space.

These guys are known for making big claims, so be careful.

Gary


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RE: reflective insulation

Thanks Gary

That's what I was guessing but I see lots of it advertized where it is installed directly against things but always thought that was not a good way to do it.

thanks
Gary Reif


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RE: reflective insulation

Actually Dupont is getting into thei Attic Wrap business on their HIGH END homes (over 600K) builders. I did try radiant guard in the last home I built for a client. Their cooling bill dropped by 1/3rd last summer.


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RE: reflective insulation

what do you think about these randant barriers just being laid over the top of the insulation in the attic?
I ran across a company at our local home show that does just lay it on top of the insulation (energydoctorinc.com)
I know I have read not to do that because dust on top of it will reduce effectiveness, but in reality I don't think it will get very dusty up there.
opinons?

Here is a link that might be useful: link


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RE: reflective insulation

thanks Gary

I already have 19" of insualtion, I am looking more for summer cooling (reflect heat) and would not look forward to stapling it up.

Gary Have you ever did any research into refelctive films applied to windows to reduce cooling needs?
thanks
Gary


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RE: reflective insulation

Hi Gary,

19 inches -- good job!

I've not done anything with reflective films for windows.
We did try a commercially applied film that I believe just absorbed the heat -- we had two of the windows crack and have to be replaced. This (I believe) was caused by the extra heat the film put into the glass panes.

It seems like a reflective film should work better.

Gary


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RE: reflective insulation

hi Gary

do you have any info on the reflective radant insulation blankets for water heaters compared to standard fiberglass blankets? I looked on your site but there is so much info (great info).
Thanks for taking the time to manage your site.

Gary Reif


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RE: reflective insulation

Hi Gary,
The Reflectix website has a scheme for using their product to insulate a water tank:
http://www.reflectixinc.com/diy/default.asp?pageIndex=563

While I generally think the R values on their site are exaggerated, the R4.5 they claim seems reasonable to me because of the two reflective layers that both face air spaces. You would have to be careful to space the Reflectix away from the tank in order to get any benefit from the inside reflective layer.

Gary

Here is a link that might be useful: DIY Reflective water heater insulation


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RE: reflective insulation

I had the company over for a quote on installing radiant insulation. 2500 sf house with catedral ceiling so about 2800 sq of product.

$4500 ... wow

i was guessing $1500-$2000


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RE: reflective insulation

I've seen ads for a spray-on radiant barrier. Gets applied in the attic to the underside of the roof. Does anyone know anything about this? Thanks


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RE: reflective insulation

Might look at this PDF file from the Reflective Insulation Manufactures Association - Their testing results on 16 heat barrier paints.

Some of these are pricey that do well, and while all have some benefits the one from sherwin williams might be worthy of a price check even though it doesnt fully meet the RIMA approval spec.

Here is a link that might be useful: RIMA, 3 page Pdf


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RE: reflective insulation

Some spray radiant barriers do very well.
Here is a link to why the RIMA study has no meaning though.

Here is a link that might be useful: RIMA study facts


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RE: reflective insulation

I just built using roof decking with radiant barrier pre-applied. I suspect that this is the only practical way to do radiant barrier insulation. I don't think any spray-on is a good idea...you may trap water from a leaking roof and never know it until the trusses rot out.


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RE: reflective insulation

Reflective insulation such as Radiaflect is designed to reflect 97% of radiant heat away from an area.. In the summer it would reflect the suns energy away from regular insulation and allow it to work more productively. In the winter it reflects the homes heat back in and saves that way.. Companies are making reference to 30% savings.. I think it would have to be salt tested .. ie.. If the house has lots of sun on it in the summer or is it shaded during the day.. Not sure how that would affect things.. Try this website www.radiaflect.com/sweetwater


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