# Bubble wrap radiant barrier for metal garage door



## ZTMAN (Feb 19, 2015)

I think you would get better results by putting rigid insulation panels in the metal channels on the door. That's what the manuf do for the insulated doors.


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## Alumifab (Jul 23, 2009)

I heard that the boards would hold the heat, but the barrier would 'prevent' the heat from getting in.
I don't mind doing either, just want to make the right decision.


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## SPS-1 (Oct 21, 2008)

Radiant barrier needs an air gap to work. Put directly on the door, not sure its going to do much. My garage door is R15 and it still gets darn hot in the garage when the sun beats on the door. 

Can't say it as a fact, but I would be happy to wager the bubble wrap does nothing.

Some info here:
http://www.greenbuildingadvisor.com/blogs/dept/musings/stay-away-foil-faced-bubble-wrap


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## SPS-1 (Oct 21, 2008)

Alumifab said:


> I heard that the boards would hold the heat


You mean the insulation would hold the heat, so don't use insulation? Nonsense.

Tell us all about the person that said this.


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## Alumifab (Jul 23, 2009)

Jim Dutton Texas home improvement radio show. 
Maybe I heard it wrong, but I don't think so. 
He said put the radiant barrier so there's a gap between the barrier and the inside of the door. Use small sheet metal screws to screw in where the doors break apart (my words). 
He said the foam board will keep the heat and not prevent like the barrier. 
He also the barrier is useless. 
I don't mean to start anything. 
I just want to make my garage a little cooler.


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## joecaption (Nov 30, 2011)

So much easier, faster and work far better to just glue the foam board to the door.
Bubble wrap screwed to the door!
Not a great plan.
Is there soffit vents?
A ridge vent?
Sheet rock on the ceiling?
Insulation over that?
Attic been air sealed?


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## ZTMAN (Feb 19, 2015)

Must have been talking about this stuff on the radio

http://www.greenbuildingadvisor.com/blogs/dept/musings/stay-away-foil-faced-bubble-wrap

Also read an article saying rigid is superior


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## Bud9051 (Nov 11, 2015)

Hi Alumifab,
The bubble wrap tries to combine two methods to block heat transfer, insulation and a radiant barrier. As an insulator it is very poor, perhaps an r-1. As a radiant barrier it offers a reflective surface on both sides and radiant barriers work to both reflect the heat (98% reflectivity) and to not transmit heat (2% emissivity). 98 and 2 are just examples.

If installed directly against a warm surface it would still reduce the heat transfer due to the low emissivity, so your garage would essentially be the needed gap. If you were to space it off of the door surface then it would have two radiant barriers in play and work even better.

One drawback is the exposed surface will get dirty which will reduce its performance.

Never tried what you are suggesting, but one plus might be the flexibility of the BW where you could cover the seams between panels and the door would still open and close properly. Test before you try.

IMO, it should make a significant difference in the heat transfer into the garage.

Bud


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## Alumifab (Jul 23, 2009)

ok, so gluing foam insulation board wins, any particular thickness?


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## Bud9051 (Nov 11, 2015)

Not sure how you draw that conclusion, as foam board only represents a thermal resistance which will still result in the inside of the door getting hot. I agree bubble wrap has a bad reputation, but radiant barriers do not and they work. It is common in climates like yours to use roof sheathing that already has a foil film covering the inside surface, for the same reasons you would use one on your door.

If you choose to apply a layer of rigid, use one with a foil facing towards the inside.

Remember, the negative hype on bubble wrap originated from exaggerated claims made by scam artists and our industry has never been able to get passed those lies. But radiant energy is real and can be greatly reduced by use of a reflective surface.

I have no objections to using both, but if you go with just a layer of rigid foam, make it thick.

Bud


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## Alumifab (Jul 23, 2009)

I just want to keep the heat out of the garage the best I can, because a fan isn't getting the job done, so I'll take advice.


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## dd57chevy (Jun 21, 2015)

I'd cut pieces to fit , get a roll of 2" wide packing tape & "give it a whirl "!

:vs_karate:


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## KarenStein (May 30, 2016)

There's a special place in Hell - or West Texas - for folks who lie as shamelessly as the bubble-wrap hucksters.

I say this, having bought a roll of the stuff. I place it on TOP of my car, and it really keeps the inside temps down in the parking lot. 

That's the only situation where the stuff can do any good. It can't reflect what it doesn't see. That means it has to be outside, not inside, in order to work.


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## Bud9051 (Nov 11, 2015)

Let's use the term "radiant barrier" instead of bubble wrap, because those hucksters sure have made it hard to have a meaningful discussion about anything radiant related.

But the truth is, radiant energy is one of the three main modes of heat transfer and definitely the fastest. RBs function in two different modes, by reflecting radiant energy (reflectivity) or by not radiating that energy (emissivity). Yes, it needs an air gap (on either side) to bread any direct conduction, except the air, but it does not need to be on the outside of our homes. Nice if we could, but not necessary. 

On the inside of the garage doors in question, having a RB facing to the inside will eliminate 98% of the incoming radiant energy, that is the radiant energy being emitted from the door. There would still be a small of conduction to the air and some convection from the surface of the RB.

The bottom line is, RBs work when hot surfaces are involved.

Bud


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## Alumifab (Jul 23, 2009)

Someone at work said to go to lowes and get Perma board. 
Cut the pieces a little big to slightly bend and pop in each door panel. He said there needs to be a little air space between the door and board with the foil facing the door. 
He said it does make a difference.


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## SPS-1 (Oct 21, 2008)

What I pulled up for Perma R Products foam board is R2.9 for a 3/4" board. That is nothing. Get at least R12. 

Joe asked earlier what you had for ventilation. That is relevant, because once the heat gets in, it stays in unless you have some ventilation.


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## Alumifab (Jul 23, 2009)

I have no ventilation other than a attic access door.


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## Alumifab (Jul 23, 2009)

The thicker the foam board the less you can bend it to provide a space between the door and board....


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## Bud9051 (Nov 11, 2015)

Did that someone at work provide you with any citations or was it just his opinion?

Be careful with following "opinions" as they are just like belly buttons, everyone has one and they are all different.

This organization has a lot of quality information on radiant barriers.
http://www.fsec.ucf.edu/en/publications/html/fsec-en-15/#foilside

Bud


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## Alumifab (Jul 23, 2009)

Thanks, I'll check it out.
I just keep hearing there needs to be space between the board and door or no there needs to be no space. 
Well, which one works, haha,.....
I don't know, I give up.


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## Usausausa (Dec 15, 2020)

I heard it works well in the cold, and way better than any amount of fiberglass if you do 2 layers with an air gap like in floor joist and bottom of joist. But if you do use foam board like suggested, if you line it with regular grocery store cooking aluminum foil it has the same affect as expensive building foil. (The bubble wrap does help) the foil will help the foam board greatly considering its radiant heat aluminum foil is blocking the heat transfer


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