Total Rebuild

[Gordon Dewald]

We have always been taught the vapor barrier goes on the hot side. Rule of thumb that means the barrier is on the inside. This keeps the vapor from getting to the cool part where it can condense.

One of the biggest issues with RV is when it is cool or cold outside. In order to try to save heat we tend to button up the unit so any washing, cooking, breathing, etc is not vented. I have not seen an older RV that contains vapor barrier. Most of the standard practice is to use minimal amounts of pink fiberglass. Not that I have seen them all and certainly in Terry's TH they have styrofoam that will serve as a barrier. Our coach is built with stryrofoam as well but one if the warnings in the manual is to watch for moisture due to lack of ventilation.

If I were to build a RV from scratch I would use the high density foam and seal it with expanding foam. Then a layer of 6 mil vapor barrier followed by the inside wall board. Excessive - of course - but I have seen the effects of moisture in the walls and the resulting rot and mold.

I am with Terry on not using plastic wrapped insulation. The plastic will keep the moisture from getting in but also prevent it from drying out should any moisture get in.

No matter what is used the unit should be properly ventilated and any leaks promptly repaired. If that is done there should be no issues for the life of the unit.

[beamisl]

Hi Guys,

I will take pictures Wed and post them. This is the area over the driver's and passenger's seats and it has lots of room for insulation. Will use a bracket to secure the flat screen for travel but would like one that drops down so we don't have to look up at the TV. We still play VHS so may keep the old one.

You know that silver backed bubble wrap that people put in their windows to protect from the UV rays and heat? You can buy it at CW in rolls. Well, some of the Cath Lab products come packaged in this stuff. They were just throwing it out so I started taking it home. I have been able to cover most of my windows, a lot of the inside of cupboards and closets, and figure by the time I am done I will be able to insulate most of the hidden areas that I think let in a lot of heat or cold. Why pay for it when they are just throwing it away.

I think bat insulation might be best up in the area I am talking about. I had thought of the spray glue and may go with that. We have a outside yellow light that is not working (over the front windshields) that I can get to right now and will probably fix that while I can replace the whole thing. It looks like it is fiberglass insulation and not very thick so I want to do that while it is open.

Going to have this guy check the radio while he is at it. We want a blue tooth and USB connection up front so may as well get it all done at the same time.

Terry, The work is looking good as usual. I can't wait to see what you do when done with this cause we know this is not the last one. I think we are getting the same weather as you because they say teens over the next few days and weekend. Like you I have just had enough of winter.

Take care all, Lynne

[Harley1994]

Gordon, I agree, except on the vapor barrier, ventilation is the key, I knew if I looked I would find the explanation of when and where to use it. here is the explanation.......Usage[edit]

The industry has recognized that in many circumstances it may be impractical to design and build building assemblies which never get wet. Good design and practice involve controlling the wetting of building assemblies from both the exterior and interior.[3] So, the use of vapor barrier should be taken into consideration. Their use has already been legislated within the building code of some countries (such as the U.S., Canada, Ireland, England, Scotland & Wales). How, where, and whether a vapor barrier (vapor diffusion retarder) should be used depends on the climate. Typically, the number of heating degree days (HDD) in an area is used to help make these determinations. A heating degree day is a unit that measures how often outdoor daily dry-bulb temperatures fall below an assumed base, normally 18°C (65°F).[4] For building in most parts of North America, where winter heating conditions predominate, vapor barrier are placed toward the interior, heated side of insulation in the assembly. In humid regions where warm-weather cooling predominates within buildings, the vapor barrier should be located toward the exterior side of insulation. In relatively mild or balanced climates, or where assemblies are designed to minimize condensation conditions, a vapor barrier may not be necessary at all.[5]

An interior vapor retarder is useful in heating-dominated climates while an exterior vapor retarder is useful in cooling-dominated climates. In most climates it is often better to have a vapor-open building assembly, meaning that walls and roofs should be designed to dry:[6] either to the inside, the outside, or both, so the ventilation of water vapor should be taken into consideration. A vapor barrier on the warm side of the envelope must be combined with a venting path on the cold side of the insulation. This is because no vapor barrier is perfect, and because water may get into the structure, typically from rain. In general, the better the vapor barrier and the drier the conditions, the less venting is required................... That is the problem that as RV'ers we face the conditions of moving our "house" from cold to warm climates, or vise versa, so there is no one way to put the vapor barrier in the most optimum location, thus I believe that's why you don't normally see a vapor barrier in an RV, best to let it breathe and dry out. I'm not disagreeing with anyone just I'm not sure if there is one size fits all answer.

[Gordon Dewald]

Hey Terry - good information. Thanks for the lesson. I learned another thing today. I am a northern boy so the warm side is inside. It makes sense though to have the barrier on the outside in the south to prevent the moisture from coming in.

Generally I figured RV did not have vapor barrier because they are not designed for continuous living. Most are only used for periods of a couple weeks or less and then sit for long periods of time.

I know our 5er has pink fiberglass and the coach has styrofoam. Thus no barrier in the 5er and coach is fundamentally a barrier in both directions.

[Harley1994]

Good Morning, Gordon, Me Too! living in the northeast the barrier is always inside, when I started to build these RV's I talked to a good friend of mine that was the head of a weatherization program in the state, and he told me some things that lead me in the direction I believe was correct, I think the reason the RV's are being insulated like yours now with the hard insulation is the manufacturer has learned a lesson. Well we got three inches of snow last night, had to come eventually .

[Harley1994]

Working in the shop today...........Building coach corners, these will finish off the front of the coach body. Pulled out the English Wheel, used to build my own repair panels and complete race car bodies.

[cwk]

Originally Posted by Harley1994

Pulled out the English Wheel, used to build my own repair panels and complete race car bodies.

Terry,

Wow! I keep learning about new stuff from you. Thank you!

[Franka548]

Terry,
Nice finish to the Tot'r body. It will let it look factory. I wasn't thinking of the vapor barrier when I said the plastic lined fiberglass, but the ease of use up in that confined space up over the drivers head. the way the RV's are used, you really would need the vapor barrier on both sides, because the heat and cold could be on either side.
Frank

[Harley1994]

Well with the extra time I have, I put together a collage of pics to bring everyone up to date with what's going on in the world of building things.

https://www.youtube.com/watch?v=MsiRxa7OaTE

Charles, Thanks! Frank, it has to be tucked up under the body and molded to the exhaust and the upper coach body, should work

[Franka548]

Terry,
Nice job on the video and picture collage. If you keep it up, they are going to be bugging you from Hollywood to come and show them how to do it , lol. Just kidding, but you do a great job anyways.
Frank

[guardrail53]

Nice Video, Terry! She is shaping up very quickly, despite the weather! Keep up the good work! Enjoy it! Rail!

[Harley1994]

Good Morning, Frank, Thanks! is it warm in Hollywood? then I'll go . Rail, Thanks! I just keep pluggin along when I can, I'm hoping the bones are done, then as it gets warmer I'll be able to start putting everything in. Well gotta Dr. appointment today, just a normal three month check up.

[Lloyd in S.C.]

Good video Terry! Enjoyed it. Nice to see it all together in one view, kinda brings it all into perspective.

Cold here also, 23* this morning. Brrrr!

L.

[ronspradley]

Terry, thanks for the new video update, great progress. Always impressed by what you are able to accomplish especially during your cold winters. I have trouble motivating myself to go outside when the temp drops to an unbearable low of around 50F !!! I am such a wiener. Looking forward to Spring which is just around the corner.

ronspradley