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Old 02-24-2011, 06:24 PM   #1
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1971 27' Overlander
Austin , Texas
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After buying an "immaculate" 1971 Overlander on Ebay, I started by removing the belly pan, the insulation (totally wet), the interior, the systems, the floor, etc.... Needless to say that the frame was rotted (fixed now), and the floor too. Now it's time to put everything together... One big questions remains though....what is the best insulation? I have seen different threads mentioning styrofoam, spacers and styrofoam, adding vents pipes, etc... I also saw a thread saying that foam (blown) is a big no-no.... HELP! My gutt feeling tells me that I should glue something hard and that doen't take the moisture to the floor baord and allow for the belly pan to breathe without taking water in - at least to the best of my abilities. ....Am I right?
Thanks ....
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Old 02-24-2011, 08:13 PM   #2
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1977 23' Safari
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Start at this post for how I used solid foam in the belly pan of my Safari. INLAND_ANDY says using the door/window foam is a bad idea because the flexing of the frame will turn it to powder eventually. I used the "flexible forever" version, so I hope I've dodged that bullet.

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Old 02-24-2011, 08:43 PM   #3
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Welcome to the forums from just up I-35. I bought 1" Dow Tuff-R polyiso insulation from the local hardware store. I plan on installing it in two 1" layers to the subfloor from underneath with 2.5" screws and roofing washers. For the curved sections of the trailer walls I'm going to use Roxul. I also will be installing the Reflectix on top of the Roxul. I'm sealing it all with normal aluminum tape.

Work is never done, so take time to play!
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Old 02-24-2011, 08:44 PM   #4
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This thread has a couple of different options for insulation under the floor:


There are lots of different opinions. You have to read everything & pick what you think is best! Good luck!

1964 Bambi II
1988 Avion 32S
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Old 02-24-2011, 11:17 PM   #5
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I did an extensive test of several methods of insulating the shell. Prodex had captured many members' fancy a couple of years ago, so I decided to test fiberglass bats, Prodex, air gaps, and solid polyethelene foam. The thread is very long, but it has all the test methods, data, and conclusions.

Using Reflectex/Prodex provided only a small improvement over fiberglass bat. This was both disappointing (I wanted to find the magic bullet) and happy (glass bat is easy to install). The solid foam was excellent, but impossible to install in the curved shell.

Let me give you one caution--if you use Prodex and tape it perfectly, you run the risk of creating traps for condensed water. I think this risk is way worse than any benefit you get over fiberglass.

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belly pan, insulation, floor repair

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