eliz65
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Post by eliz65 on Jul 22, 2013 19:16:20 GMT -8
We are getting ready to put up the birch paneling soon, and I just want to make sure I understand what's to be underneath it. I found another thread online that said we need a paper or plastic vapor barrier. Is it just plain plastic? Or is paper better? If paper, what type?
Thanks so much!
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gonekayaking
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Post by gonekayaking on Jul 22, 2013 19:59:14 GMT -8
vapor barrier if using it would go on the outside of trailer framing, under the skin, not on the inside. Did you insulate between the framing? Any thing that will fit the 3/4 inch is good-- pink, foil backed foam or foil bubble wrap insulation. It's not a huge space so it's not really going to do a lot but it does help some with noise and with temperature.
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mobiltec
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Post by mobiltec on Jul 22, 2013 20:11:27 GMT -8
Roberts Unison from Home Depot is what I use. It also gives your trailer that "Puff Factor" that is so desireable. Makes the skin stronger by purshing out a bit. Also adds insulation quality.
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eliz65
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Post by eliz65 on Jul 23, 2013 6:36:35 GMT -8
Thanks so much!
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tiajannet
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Post by tiajannet on Jul 23, 2013 11:44:47 GMT -8
Would this barrier help prevent leaks from soaking the framing?
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mobiltec
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Post by mobiltec on Jul 23, 2013 12:25:40 GMT -8
Would this barrier help prevent leaks from soaking the framing? The only thing that prevents leaks from soaking the framing is proper sealing of the metal and openings like windows, doors and vents. The vapor barrier is there for condensation that builds up on the inside of the metal skin due to temperature and humidity changes. What you don't want is "leaks".... No barrier in the world will prevent leaks... That would be kinda like trying to fix a cracked aquarium with scotch tape.
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Post by bigbill on Jul 23, 2013 12:57:07 GMT -8
Proper design calls for the vapor barrier to be installed to the winter heated side of any insulation no matter where it is installed.
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mobiltec
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Post by mobiltec on Jul 23, 2013 13:08:40 GMT -8
Bill we've been through this one before. We are talking metal trailers here, not wooden houses. Condensation can and does form on the inside of the metal skin and will drip into the insulation and framing. It's the only reason it's there really. Although the stuff I use also adds to the R factor of the insulation. Have you ever woke up in an un-paneled van when it was cold and moist outside? The top of the inside is covered with droplets of water just waiting to fall on you the moment you make a move. That's the vapor/moisture that I am attempting to prevent from reaching the insulation and the framing and paneling.
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gonekayaking
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Post by gonekayaking on Jul 23, 2013 15:55:07 GMT -8
Mobil I was just at the big orange box, and next to the Roberts Unison they had rolls of Traffic Master which had a foil backing on both sides of the thin foam, maybe a bit thicker. It was a lot more expensive (45/100sf vs 27 I think for the Roberts unison). But I'm thinking since the foil bubble wrap is great stuff this might be too, but wonder whether it has the same vapor barrier advantage?
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mobiltec
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Post by mobiltec on Jul 23, 2013 16:18:16 GMT -8
Mobil I was just at the big orange box, and next to the Roberts Unison they had rolls of Traffic Master which had a foil backing on both sides of the thin foam, maybe a bit thicker. It was a lot more expensive (45/100sf vs 27 I think for the Roberts unison). But I'm thinking since the foil bubble wrap is great stuff this might be too, but wonder whether it has the same vapor barrier advantage? I haven't looked at that stuff yet. But I could never understand foil backing being of any advantage in a metal shell. A radiant barrier isn't what I was going for when I started using the Unison which is actually designed for a completely different purpose than being used as a vapor barrier. That's why it's found in the flooring section of the store. Because it is used for underlayment in flooring. Let's not forget the "Puff Factor" that it adds to the looks and feel of the metal skin as well. Between the Unison and the fiberglass insulation I get a really solid puff factor with my trailers.
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Post by bigbill on Jul 23, 2013 17:12:21 GMT -8
Yes Larry I have but where did the moisture come from not through the steel of the van but from the moisture inside the van that was collecting on the cool surface that is why the moisture barrier should be on the winter heated side and it ideally would not have any cracks or breaks in it which is nearly impossible in these trailers even if you put the vapor barrier on the outside all you have done is allow the moisture to collect inside the insulation causing it to lose R value and to channel the moisture to the wood framing which in the long run will promote mold and rot. the reason people get away with it is most trailers aren't used much in cold weather. I worked for Owens-Corning for nine years and the things people do to render insulation not as effective could fill this page. Moisture in insulation not only affects the R value but it also affects the resistance to sound transmission. In many parts of the country houses were/are made from steel and aluminum and the inside vapor barrier is even more important. Companies have been studying this for the last 60 years. Most of the moisture in a trailer comes from 3 sources Cooking, breathing, and combustion not through the aluminum skin, if it is properly sealed. The wrap you see on a modern house exterior is mostly there to prevent air infiltration.
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mobiltec
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Post by mobiltec on Jul 23, 2013 17:16:53 GMT -8
Yes Larry I have but where did the moisture come from not through the steel of the van but from the moisture inside the van that was collecting on the cool surface that is why the moisture barrier should be on the winter heated side and it ideally would not have any cracks or breaks in it which is nearly impossible in these trailers even if you put the vapor barrier on the outside all you have done is allow the moisture to collect inside the insulation causing it to lose R value and to channel the moisture to the wood framing which in the long run will promote mold and rot. the reason people get away with it is most trailers aren't used much in cold weather. I worked for Owens-Corning for nine years and the things people do to render insulation not as effective could fill this page. Moisture in insulation not only affects the R value but it also affects the resistance to sound transmission. In many parts of the country houses were/are made from steel and aluminum and the inside vapor barrier is even more important. Companies have been studying this for the last 60 years. Most of the moisture in a trailer comes from 3 sources Cooking, breathing, and combustion not through the aluminum skin, if it is properly sealed. The wrap you see on a modern house exterior is mostly there to prevent air infiltration. To me it doesn't matter where it comes from. It's where it collects at that Im protecting against. This would be on the inside of the metal surface. That is the surface that it condenses on. It's caused by the temperature variance. Warm air hits cold metal and the moisture in that warm air condenses and turns to drops on that surface where it condensed at. That is the moisture I am protecting the trailer from. If people want to put another moisture barrier on the inside of the paneling too that's ok with me.
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Post by bigbill on Jul 23, 2013 17:46:53 GMT -8
Larry you are right but if it can't get to the cold alum then it will collect on the inside of cold vapor barrier and get the insulation wet then wick over to the wood framing. to prove this to yourself take that same metal van you were talking about cover the entire inside with a plastic vapor barrier and tape all the seams then on a cold zero night sleep in it all night and you will see water dripping off off the vapor barrier because it then becomes the coldest surface the vapor can get to. in an ideal world the trailer walls would be a foot thick and we could insulate them and then have a ventilated area next to the outside skin to take any vapor that leaked through out the vents but when we are dealing with an inch of space it becomes a whole new ball game.
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mobiltec
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Post by mobiltec on Jul 23, 2013 17:49:58 GMT -8
See why I prefer tents?
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kathleenc
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Post by kathleenc on Jul 23, 2013 17:50:33 GMT -8
well now I'm really confused. I feel like I should either use no vapor barrier at all, OR use two, one inside the paneling under the insulation and one inside the metal skin on top of the insulation.
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