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Open Roads Forum  >  Travel Trailers

 > Insulation in the walls of my tt

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Missouri Jay

Washington, MO

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Posted: 07/01/11 03:03pm Link  |  Print  |  Notify Moderator

I'm redoing my interior of my tt, what are everyone's thoughts with what kind of insulation to use? Fiberglass or foam board?

BobsYourUncle

Surrey, BC Canada

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Posted: 07/01/11 03:40pm Link  |  Print  |  Notify Moderator

Foam board will do a better insulating job, but there are a number of drawbacks.

You have to fill every nook and cranny, otherwise you will have a lot of air infiltration through the gaps.
Foam will take you 10 times longer to install.
Foam is a lot more expensive.

Regular fiberglass insulation is not as effective for insulating value but it is a lot easier to install and stuff into cracks etc.

If foam gets wet it does not hold water the way fiberglass does. It will absorb to a certain degree, but dries out easier. If fiberglass gets wet, it will go all gross and moldy before it ever dries out, especially when there is no ventilation or air movement.

Fiberglass is lighter but really wont make that much difference for a whole trailer.

Fiberglass will compress if you have any bulges in it. So when putting the paneling back on or the outside siding, you won't get and bulging there. With foam, it must be flat or it will push out whatever you are putting back on over the studs.

If you use foam, you could use a caulking of some kind to fill all the voids where it is not tight to the studs and plates etc. but you have to make sure the caulking used will not eat the foam. Many of them will.

Foam will give you better sound deadening properties over fiberglass.

Uhhhh, thats all I can think of off the top of my head!!


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nypatnva

Amelia Ct Hse Va

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Posted: 07/01/11 04:48pm Link  |  Print  |  Notify Moderator

I have restored five trailers and one pu camper. I always use foam board to replace the fiberglass. Doesn't hold the moisture if you have a leak, Have had good luck with it and helps if you camp in the winter. JMHO


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Gdetrailer

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Posted: 07/01/11 05:03pm Link  |  Print  |  Notify Moderator

Very good question!

As other posts have noted, some plus and minus with most types of insulation. But one should understand that there are some variations or types of foam board insulations.

They vary in the R factor per inch, most foams actually do not give much R factor per inch over fiberglass. Only one that does, that is polyiso type insulation

Typically polyiso will give R6.5 per inch compared to fiberglass at R3.71 per inch.

POLYISO FACTS

How can you tell if the insulation board is polyiso? In board form it will be yellow color foam with foil backing on both sides of the board.

Main draw back is cost, polyiso boards are considerably more expensive than any other form of insulation (fiberglass being the lowest cost per R factor) and time involved fitting every piece.

In my TT rebuild I exclusively used polyiso boards, yes it cost more, was more time consuming but I can attest to the fact that my rebuilt TT is much quieter than it was before. Can't really tell if it helped for cooling or heating since I upgraded the A/C and furnace while I was at it.

mosseater

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Posted: 07/01/11 05:18pm Link  |  Print  |  Notify Moderator

This stuff is great to work with. Good Shepherd
You can hit it with a hose, let it out in a rain storm, doesn't matter. It won't slump and dries fast, stays in position. Recommended by the International Log Builder's Association. Another plus, it doesn't itch! And not a carcinogen!


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husk

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Posted: 07/01/11 04:48pm Link  |  Print  |  Notify Moderator

you did a good job, Bob..........obviously, wet fiberglass is a nightmare..and nothing good can come from it.....

I have always wondered about the allegation that block foam will take water (at least some).....the foam cups for drinks are impervious to water..is the block foam different than that?

In my un-expert opinion.....foam is by far the better choice, and it isn't really close....

BobsYourUncle

Surrey, BC Canada

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Posted: 07/01/11 06:47pm Link  |  Print  |  Notify Moderator

husk wrote:


I have always wondered about the allegation that block foam will take water (at least some).....the foam cups for drinks are impervious to water..is the block foam different than that?


Initially, foam is impervious to water....
However, if you subject a type one - low density styrofoam to water on an ongoing basis, it will absorb it.

Case in point:
Over the years I have used type 1 foam glued to aluminum sheets as an insulation for above aluminum patio covers. I took one apart once to modify the system as it had been leaking for some time. When I pulled the insulated roof off, (3/4" foam on aluminum), it was saturated in the areas where water had been running on it. It held a lot of water. I would imagine that it took at least 2 to 3 years of constant contact to absorb all that water.

johnrbd

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Posted: 07/01/11 05:19pm Link  |  Print  |  Notify Moderator

At least 4 inches of foam board, all around, including windows, should keep it well insulated.





Phathead

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Posted: 07/01/11 05:32pm Link  |  Print  |  Notify Moderator

What about closed cell spray foam? I have read quite a bit about it and seems like an ideal insulator for a camper. Costly though. Anybody care to way in with more info\knowledge.

Missouri Jay

Washington, MO

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Posted: 07/01/11 05:50pm Link  |  Print  |  Notify Moderator

Thank you everybody for the good advice. I would say it is unanimous for the foam

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