Possibly stupid question about condensation behind insulatio

Bus, Microbus, Transporter, Station Wagon, Vanagon, Camper, Pick-Up.

Moderators: Sluggo, Amskeptic

Post Reply
Marya70Riviera
Getting Hooked!
Status: Offline

Possibly stupid question about condensation behind insulatio

Post by Marya70Riviera » Fri Jun 26, 2015 9:33 pm

I'd ask on thesamba where things get answered really quickly due to how many people are on there but said people HATE insulation questions. It's so funny - it brings out the worst in them. :argue: Some think insulation (or modern methods) is unnecessary and will only pose a threat re. rust, others say it's not a minimalistic enough attitude, putting too much thought into insulation - like it's morally wrong somehow and they're missing the point of simplicity and ruggedness or something like that (?) and yet others swear by it... yet all seem defensive about it. It's funny!

The one thing everyone seems to agree on is this: whatever you put on there should be essentially stuck well onto the metal wall/panel/skin (?) so that no condensation can form behind it, resulting in rust. In my case I'm putting a cheap 1.5" crawlspace insulation over random pieces (about 30% coverage) of peel & stick Dynamat for dampening of vibration noise. It seems ridiculous that the difference in thickness and quantity between the Dynamat and the main insulation should pose a threat, but is it possible I should be concerned about the "air space" between where the Dynamat will end and the main insulation will go over it, if that makes sense? I'd say it's a non-issue but the Dynamat people imply I should be concerned since i'm putting two different things together like that. Yet so many people have done this...

Insulating - for both noise-dampening and temperature - doesn't feel very important to me right now but the primary goal (while all panels, floors and furniture are out) is to have no regrets after everything's all back in!! I'm hoping I'll be long dead before all this crap comes out again! :flower:

On another note, I would think roof insulation wouldn't be as necessary for those of us with full-sized white pop tops, don't you think?

Thanks!
Marya

User avatar
satchmo
Old School!
Location: Crosby, MN
Status: Offline

Re: Possibly stupid question about condensation behind insul

Post by satchmo » Sat Jun 27, 2015 11:49 am

I think you can do whatever you want in the cavities where there is no water intrusion. VW used to put some plain fiberglass insulation in the space behind the sink/stove cabinet in campers, and there weren't any big issues of which I am aware other than folks spilling water behind the cabinets.

The only space where you cannot put insulation is behind the front door panels. It gets wet in there when it rains. Using stick on sound deadener in that space is okay, as long as it is not water absorbent. But it has to stick really well. If it peels and comes into contact with your window when you roll it down, you get big problems.

If you sleep (or do other humidity producing activities) in your bus in cold conditions, you might need to worry about condensation on the inner surface of the sheet metal inside the panels. That can get the insulation wet. To prevent it, put a vapor barrier over the insulation before you replace the interior panel.

In one camper that I took apart, the previous owner had tightly fitted little blocks of polyiso foam board insulation into the sliding door and the cargo bay panels. It looked nice and dry, so I left them in place. It would have been better for sound if he had put a few sheets of Dynamat or similar on first, but because they were crammed in so tight, they provided some vibration dampening on their own.

Good luck,

Tim
By three methods we may learn wisdom:
First, by reflection, which is noblest;
second, by immitation, which is easiest;
and third, by experience, which is bitterest. -Confucius

Marya70Riviera
Getting Hooked!
Status: Offline

Re: Possibly stupid question about condensation behind insul

Post by Marya70Riviera » Sat Jun 27, 2015 4:43 pm

satchmo wrote:I think you can do whatever you want in the cavities where there is no water intrusion. VW used to put some plain fiberglass insulation in the space behind the sink/stove cabinet in campers, and there weren't any big issues of which I am aware other than folks spilling water behind the cabinets.

The only space where you cannot put insulation is behind the front door panels. It gets wet in there when it rains. Using stick on sound deadener in that space is okay, as long as it is not water absorbent. But it has to stick really well. If it peels and comes into contact with your window when you roll it down, you get big problems.

If you sleep (or do other humidity producing activities) in your bus in cold conditions, you might need to worry about condensation on the inner surface of the sheet metal inside the panels. That can get the insulation wet. To prevent it, put a vapor barrier over the insulation before you replace the interior panel.

In one camper that I took apart, the previous owner had tightly fitted little blocks of polyiso foam board insulation into the sliding door and the cargo bay panels. It looked nice and dry, so I left them in place. It would have been better for sound if he had put a few sheets of Dynamat or similar on first, but because they were crammed in so tight, they provided some vibration dampening on their own.

Good luck,

Tim
Thanks so much Tim! Yeah that sounds smart - the foam board insulation. I've heard of others doing that. The side panels in the main part of the bus are apparently at-risk for my bus because of the slider windows (have found some rust). I think if you were the ONLY person ever to be in your bus it would be fine but with kids and dumb adults having access to it, there's always the chance someone could leave a window cracked without my knowing about it. The only thing I wonder about - re. vapor barrier in those areas - is whether it's necessary if all parts being installed are waterproof. If I once knew the answer, I no longer remember as my head may soon explode from too much info coming in lol. I keep being told only the front doors should have vapor barrier. Geez... there's so much conflicting info. I was hoping to just go 1) Dynamat 2) waterproof insulation 3) re-install interior wall panels. What do you think? Thanks again! :)

Marya70Riviera
Getting Hooked!
Status: Offline

Re: Possibly stupid question about condensation behind insul

Post by Marya70Riviera » Sat Jun 27, 2015 4:46 pm

Oh and here's the crawlspace insulation that looks like it'd be pretty good. I got a sample and it's nice and thick without being too thick. Doesn't seem too heavy either:

http://www.insulationsolutions.com/cont ... er/4x9.pdf

It just occurred to me though - I don't know how much to get! Anyone know how much I should get?!! I've been searching and can't find a number for basic insulation areas of typical bay window bus, of course! I guess I could start with less and order more if necessary but it would be nice to come up with a close-enough number not to have to!

User avatar
satchmo
Old School!
Location: Crosby, MN
Status: Offline

Re: Possibly stupid question about condensation behind insul

Post by satchmo » Sat Jun 27, 2015 5:25 pm

The vapor barrier in the front doors is really more of a water barrier. When it rains, you get a river of water into the front door cavity. The plastic liner for the front doors is placed in such a way that it keeps water away from the interior panel and lets it move on down to the weep holes at the bottom of the door. See Colin's write up here:

viewtopic.php?f=49&t=9122

I don't know how well the crawlspace insulation will work. I imagine it is fairly expensive. I'd stick with something cheap since I'd have no idea how much will be enough to finish the job.

Rain coming in through and open slider window is an all together different issue. Even expertly applied vapor barrier won't be much help if water is draining in from the window and down behind the interior panel.

Tim
By three methods we may learn wisdom:
First, by reflection, which is noblest;
second, by immitation, which is easiest;
and third, by experience, which is bitterest. -Confucius

Marya70Riviera
Getting Hooked!
Status: Offline

Re: Possibly stupid question about condensation behind insul

Post by Marya70Riviera » Sat Jun 27, 2015 5:43 pm

satchmo wrote:The vapor barrier in the front doors is really more of a water barrier. When it rains, you get a river of water into the front door cavity. The plastic liner for the front doors is placed in such a way that it keeps water away from the interior panel and lets it move on down to the weep holes at the bottom of the door. See Colin's write up here:

viewtopic.php?f=49&t=9122

I don't know how well the crawlspace insulation will work. I imagine it is fairly expensive. I'd stick with something cheap since I'd have no idea how much will be enough to finish the job.

Rain coming in through and open slider window is an all together different issue. Even expertly applied vapor barrier won't be much help if water is draining in from the window and down behind the interior panel.

Tim
Again, thank you Tim! I wonder if there are weep holes beneath those panels on the sides in the main area of bus or if they could be drilled (is that nuts?!). I've seen rust in that area time and time again on these Rivieras from those slider windows. As for the insulation, the guy is selling it to me - if I decide to buy it - for very cheap. Seems as good as many other products for this job if not better. Not sure if it'll be quiet though, haha. I read somewhere that some insulations are super noisy - crinkle crinkle crinkle! But I don't think this would be an issue. The other thing is that I can just get enough to do only any areas that I won't have easy access to later after floors/furniture are re-installed. Cause I just want to get camping in it - I have plenty of time to install the rest of the insulation later since areas like sliding door, engine compartment door and front cab area can be gotten to after furniture is in. I don't think I'm going to bother with headliner as the original foam looks relatively good for what it is an in tact, and plus it has the full-sized Riviera pop top over it. Seems a waste of time/energy/$! As for truly keeping out heat or cold when camping, window mats are what would probably make more of a difference than anything else! In the end this all feels pretty unnecessary for the amount of time I may actually camp in extreme temperatures but oh well - it'll be nice to know it's so good & tight and ready for whatever. I hope to have the bus in the family for many more generations (has been with us since the beginning - 1970) so I feel okay about spoiling it - to the extent that I can afford to anyway. :king:

User avatar
Amskeptic
IAC "Help Desk"
IAC "Help Desk"
Status: Offline

Re: Possibly stupid question about condensation behind insul

Post by Amskeptic » Wed Jul 01, 2015 10:57 am

Marya70Riviera wrote: I wonder if there are weep holes beneath those panels on the sides in the main area of bus or if they could be drilled (is that nuts?!).
In the end this all feels pretty unnecessary for the amount of time I may actually camp in extreme temperatures but oh well - it'll be nice to know it's so good & tight and ready for whatever.
Rely on sleeping bag and companions for warmth, let the interior upgrades address sound and dryness. I recommend that you leave an exposed inch along the bottoms of side walls and exposed inch width edges of flooring.

I drilled holes in my floor to help get rid of any water accumulation from leaky windows. Two little holes under the bench seat in the valleys of the floor corrugations, two little holes inside the side panels that drain into the rocker sills, and I found that there were four pre-drilled holes along the floor at the center aisle, filled with rubber plugs from the factory, I removed the two inner plugs.

Keep it light and simple. Water has to leave. VW used horsehair-ish insulation above the headliner on passenger buses for a very good reason. It holds moisture and yet allows water to evaporate readily.
Colin
BobD - 78 Bus . . . 112,730 miles
Chloe - 70 bus . . . 217,593 miles
Naranja - 77 Westy . . . 142,970 miles
Pluck - 1973 Squareback . . . . . . 55,600 miles
Alexus - 91 Lexus LS400 . . . 96,675 miles

User avatar
hambone
Post-Industrial Non-Secular Mennonite
Location: Portland, Ore.
Status: Offline

Re: Possibly stupid question about condensation behind insul

Post by hambone » Wed Jul 01, 2015 3:03 pm

I used the NASA silver bubblewrap stuff along the walls and ceiling with some Dynamat here and there. No vapor barriers except the front doors, water vapor doesn't usually get between the walls in back. So far I'm happy with it, seems a lot better than fiberglass and it's cheap n' easy to install.
http://greencascadia.blogspot.com
http://pdxvolksfolks.blogspot.com
it balances on your head just like a mattress balances on a bottle of wine
your brand new leopard skin pillbox hat

Marya70Riviera
Getting Hooked!
Status: Offline

Re: Possibly stupid question about condensation behind insul

Post by Marya70Riviera » Sat Jul 04, 2015 1:14 pm

Thanks all for the great replies! Hey Bob did you glue that stuff in or just shove it in there? Colin I appreciate all that detail and in fact (duh) had read those words of yours before! I'm hoping to meet you tomorrow at Kevin's. :) I'm even gonna drive the ol' bus over there if I can get away! :bounce:

Bob - when can you put the new (rebuilt) distributor in?

I got Dynamat in the mail - just enough to do a basic job in the most vibration-y places.

Post Reply