Is there much thermal bridging from the aluminum wall studs?

[SuiteShopping]

Do I recall seeing some brochure showing aluminum wall studs? Doesn't that provide a ready path for heat going through the wall (as well as noise)?

Even wooden studs will drop a theoretical R-15 wall to R-11 with 16"OC once the overall heat transmission is calculated---so I would think that the energy compromise would be even more severe with aluminum studs.

So is an RV wall of aluminum studs significantly less energy efficient (and noise compromising) than 2x4 lumber wall studs?

[netjam]

I think you are correct. I know on my Elite Suite any morning that dew was present you could see exactly where the studs were on the outside wall. Having said that I think you will find the sound transfer is less and the heat transfer is less than most rvs. Its a trailer not a house. DRVs are house like, but not houses. I think there are lots of other things you will find that are more bothersome than the heat or sound transfer.

[SuiteShopping]

Thank you. This is exactly the sort of information I need from current owners. Comments:

Originally Posted by netjam

I think you are correct. I know on my Elite Suite any morning that dew was present you could see exactly where the studs were on the outside wall.

So you are saying that when conditions outside produce dew on the outside siding of your Elite Suite RV, the dew is visibly missing every 16" (or is it 24"??) in vertical strips where the aluminum studs are leaking heat? {Or are you describing some condensation in your outside walls inside of the RV at those times???}

Originally Posted by netjam

Having said that I think you will find the sound transfer is less and the heat transfer is less than most rvs. Its a trailer not a house. DRVs are house like, but not houses.

Good to hear. So you have felt that your DRV tends to be much quieter than most other RVs? (Or perhaps moderately quieter? Or considerably quieter???) I know that that is a hard question but any details of your experiences is much appreciated.

I"m told that for the year 2007, Select Suites and Elite Suites had basically the same wall construction and R-factor numbers, so your experience is probably very much applicable to my situation.

Originally Posted by netjam

I think there are lots of other things you will find that are more bothersome than the heat or sound transfer.

I assume that you are saying that the bigger differences that I will find between a $10,000 year 2000 fifth-wheel and a $28,000 price on a 2007 Select Suites will involve other factors. Keeping in mind that I don't plan to tow my RV on the road for years at a time, what do you think will make me wish I had bought a Select Suite instead? {You've been so helpful that I just can't resist questioning your further. Thanks.}

[netjam]

Yes...dew is missing on the outside so you can see where the studs are.

I have only owned 2 rvs so my experience is small, but my Elite was much quieter/warmer than my current KZ.

What I tried to say was that the sound/heat transfer in your rv (any brand) will be of small concern when compared to other problems or irritations you are likely to encounter. I love the rv lifestyle but there are lots of challenges in owning a RV.

[hitchup]

We can see the studs on frosty mornings only. No frost where the line of stud is.

[Motor31]

RV construction is all about compromise. Weight vs strength is one consideration. As long as you have to build them for the lowest common tow vehicle situation they will be less than efficient in some or all areas. Even stick house have downsides, for example termites are not much of a concern for RVers but they are pretty big for stick houses.

Decide what is important to you and choose from the RV's out there that cater to your concerns. To me strength and reliability trump the paltry difference between temperature transfer variations of the two construction methods.

[SuiteShopping]

Originally Posted by Motor31

RV construction is all about compromise. Weight vs strength is one consideration. As long as you have to build them for the lowest common tow vehicle situation they will be less than efficient in some or all areas. Even stick house have downsides, for example termites are not much of a concern for RVers but they are pretty big for stick houses.

Decide what is important to you and choose from the RV's out there that cater to your concerns. To me strength and reliability trump the paltry difference between temperature transfer variations of the two construction methods.

Thank you for your advice (and to everyone who commented!) Much appreciated.

My purchase will be for long-term stationary use and so highway factors like tow weight are not as important to me.

I'm concerned that heat transfer is closely related to sound/noise transmission.

[Motorcycle Jack]

DRV uses a thermal layer on the inside before the paneling is put on. On the outside you do see the aluminum studs location but on the inside there isn't much difference between the stud location and space in between. You can see the construction video here: http://drv-owners-manual.com/drv-sid...struction.html on my owners site.

[Motor31]

If you are looking for a simple stationary housing situation I strongly suggest you invest in a park model rather than an RV. You will get better insulation with thicker walls, real residential appliances / plumbing and proper 110 volt wiring meant to handle full time load use load rather than primarily 12 volt wiring and lighting. On top of that you will find that you get far more for your dollar that way as well. Later on if you decide to sell it you should get more back in resale than in a multi year old RV trailer.

[SuiteShopping]

Originally Posted by Motor31

If you are looking for a simple stationary housing situation I strongly suggest you invest in a park model rather than an RV. You will get better insulation with thicker walls, real residential appliances / plumbing and proper 110 volt wiring meant to handle full time load use load rather than primarily 12 volt wiring and lighting. On top of that you will find that you get far more for your dollar that way as well. Later on if you decide to sell it you should get more back in resale than in a multi year old RV trailer.

For contractual reasons with the co-owner of the property, I don't have that option. (Plus, in some types of flood-plains, "quick-drive-off" capabilities are required----so fifth-wheels are fine but "loosely attached" more permanent structures are not.) So there are many kinds of situations where a fifth-wheel is a viable option but park models are not. That is my reality presently.

Thank you for your suggestion!

[SuiteShopping]

Originally Posted by Motorcycle Jack

DRV uses a thermal layer on the inside before the paneling is put on. On the outside you do see the aluminum studs location but on the inside there isn't much difference between the stud location and space in between. You can see the construction video here: http://drv-owners-manual.com/drv-sid...struction.html on my owners site.

Yes, I had found online several different DRV brochures from over the years---and the wall construction diagrams worried me considerably. I have a background in construction and building supply--- and the double "moisture barrier"/vapor barriers is a huge red flag that has concerned me. The last thing you want to do is trap moisture between barriers and create a wall which can't breathe. (Therefore, such layers would never be allowed in home construction. Indeed, the layers and their relative positions must be adjusted for the climate or one gets in-wall condensation and mold problems. There's about a 100mile "in-between climate" zone which happens to go through my area of Texas (you can see it on national energy management maps zoned for comparing "heating days" and "cooling days" zones) where NO vapor barrier should ever be used. In fact, until a few years ago, some communities still followed old codes which actually encourage mold instead of preventing it.

My own experiments with humidity/temperature/dewpoint USB sensors in walls have confirmed just how problematic vapor barriers can be. Accordingly, after seeing the DRV and other manufacturer's construction illustrations in their brochures, I got nervous about all of them. Walls should always be able to breathe. A breathable wall is a dry wall because it can dry out in all directions. A semi-permeable barrier can keep out water while allowing water vapor to pass through. (Think of it like Goretex fabrics used in ski and mountain-climbing coats. Sweat evaporates quickly while rain rolls right off. A properly engineered wall breathes in the same way.)

After studying RV construction methods, I'm not at all surprised that dry rot is so very common, even among far too many higher-priced units. Indeed, those manufacturers often advertise and brag about construction method and layers which would cause a lot of building contractors to lose their licenses. (But I suppose a large number of layers in walls and roofs looks like a good thing to many potential customers.)

[wingnut60]

I would question that dry rot is "so very common" as most of the instances brought to light on RV forums relate to unnoticed long-term leaks. If dry rot was 'very common' I would expect every RV would suffer from it? At what age would you expect this to become evident, or of consequence?
Joe

[porkchop]

I'm waiting to see how dry rot will affect the aluminum in mine.

Bill

[wingnut60]

Now, Bill, dry rot in aluminum is lovingly referred to as 'corrosion'--don't want to confuse the two.
I have watched to stud outlines on the side of my trailer in the early morning for many years--probably nothing left of them by now.
Joe

[SuiteShopping]

Originally Posted by wingnut60

I would question that dry rot is "so very common" as most of the instances brought to light on RV forums relate to unnoticed long-term leaks. If dry rot was 'very common' I would expect every RV would suffer from it? At what age would you expect this to become evident, or of consequence?
Joe

Very good questions.

Yes, once wood has become wet (such as from wall condensation, a case where no leaks are involved) ---even just one time in an unusual dew point "climate event" -- the fungi get started eating the wood. Then the process continues, even very slowly if new condensation feeds it and speeds it up, for many years. From studying the insides of RV walls, I get the impression that a lot of RV owners are unaware that dry rot is underway. Not until they start feeling soft spots on the floor or notice that the condensation "lines" on the outside (as described by previous posts) start getting wider will they realize that they have a problem slowly developing.

I would bet that a lot of humid coastal areas have dry rot at work on RVs without owners' awareness. And for RVs with fiberglass and wool insulations, once they get wet, they tend to sag and develop "thermal paths" as well as new condensation-encouraging areas. And that is why the lack of wall "breath-ability" caused by vapor barriers concerns me. The laws of physics apply everywhere, so when RV manufacturers ignore what building codes force home-builders to plan for, dry rot is bound to happen. I've been fascinated to see that some of the companies that apply those codes properly in building their "park models" ignore the same laws of physics on the RVs they build. But as I said, a lot of consumers probably look at the RV brochures of walls and roof diagrams and think each layer shown is beneficial because it looks complex and positive.

[Motorcycle Jack]

Wow, to go from asking if there is any thermal bridging due to the aluminum studs to an expert on how the humidity is trapped in RV walls to cause damage in one post! Man, next time I design an RV I'll be calling YOU> NOT! But thanks for your opinion (just like everyone you have one and are entitled to post it). But post like yours are called trolling and all of us tend to disregard your opinion after that, have an honest question you need an answer too please post.

[porkchop]

I still want to see how the aluminum is subject to dry rot. My third grade education can't compute. You do know in the more northern climates (think Canada) vapor sealing is the law of the land. Nebraska also.

Bill