Insulating RV With Polystyrene

 
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Old 08-01-2013, 10:11 PM   #1
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Insulating RV With Polystyrene


Hello,


I have an RV that has an insulated cavity thickness of 2" (most of the RV) to 1" (The cabover).

I am looking to get the best insulative properties for the money, and I can pretty much afford the polystyrene sheets.

Is there going to be a big advantage to going with the foil covered sheets of polystyrene?

Also, should the entire cavity be filled with the polystyrene, (I.e. for the 2" thick cavities, use 2" thick sheets, for the 1" thick cavities, use 1" thick sheets) or should there be an air gap of some sort to help with the insulative properties?
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Old 08-02-2013, 06:32 AM   #2
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Re: Insulating RV With Polystyrene


The foil only helps if there is an air gap. However, some testing done by the fantastic folks at CCHRC has shown not by very much. If you want some heavier reading, check it out: http://cchrc.org/docs/reports/TR_201...d_Climates.pdf

I'd fill it with the best insulation you can afford. EPS, XPS, or polyisocyanurate

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Old 08-02-2013, 07:08 AM   #3
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Re: Insulating RV With Polystyrene


Golden View nailed it - just make sure there are no gaps / voids / places where water can condense & sit
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Old 08-03-2013, 12:08 AM   #4
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Re: Insulating RV With Polystyrene


Okay, thanks!

Which one of those above has the highest R factor?

And, I want to completely fill the void, right?
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Old 08-06-2013, 08:34 PM   #5
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Re: Insulating RV With Polystyrene


Wondering if someone can answer the above question? I have a similar situation and would appreciate advice!

GT
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Old 08-06-2013, 09:27 PM   #6
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Re: Insulating RV With Polystyrene


Polyiso sheets or closed cell polyurethane foam if you are spraying it in.
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Old 08-06-2013, 09:40 PM   #7
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Re: Insulating RV With Polystyrene


Quote:
Originally Posted by Golden view View Post
Polyiso sheets or closed cell polyurethane foam if you are spraying it in.


If I have a inch and three quarter thick gap, should the sheet be inch and three quarters thick?
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Old 08-06-2013, 10:01 PM   #8
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Re: Insulating RV With Polystyrene


Sorry, didn't answer your full question. It would provide the most insulation if you filled the cavity, but it won't hurt too much if it doesn't quite. So an inch and a half sheet in the 1 3/4 cavity would be fine.
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Old 08-06-2013, 10:03 PM   #9
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Re: Insulating RV With Polystyrene


Quote:
Originally Posted by Golden view View Post
Sorry, didn't answer your full question. It would provide the most insulation if you filled the cavity, but it won't hurt too much if it doesn't quite. So an inch and a half sheet in the 1 3/4 cavity would be fine.
Thank you very much
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Old 08-07-2013, 04:52 AM   #10
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Re: Insulating RV With Polystyrene


You really should fill the complete cavity so you don't have a condensing surface inside the bay - a lot depends though on where you store & use your RV

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