| Author |
Message |
Keith Kroeker (Keith) (65.33.33.8)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, November 18, 2002 - 4:21 pm: | |
Sorry one more question.... I've read alot about sprayed foam insulation being put into conversions... Noone talks about traditional fiberglass roll insulation. Is typical residential insulation not good for conversions? Pros vs Cons? Ideas to save money? |
JimStacy (12.87.109.5)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, November 18, 2002 - 4:32 pm: | |
You only have about 1 1/2" of space. The hot spray urethane has an "R" factor of 7 per inch, The fiberglass is about half of that.
The fiberglass will absorb moisture.
The urethane also seals and quiets the coach.
Fiberglass is better than nothing, but not much. |
RJ Long (Rjlong) (24.127.74.29)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, November 18, 2002 - 11:57 pm: | |
Keith -
I agree with Jim's comments. . . plus I'll add this one:
Have it spray foamed by a professional. It's well worth the bucks to have it done right the first time.
RJ
PD4106-2784
Fresno CA |
carl mci9 (66.144.52.102)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, November 20, 2002 - 2:00 pm: | |
I have an MCI 9 and when the inside pannels are off the bus so that it can be insulated with foam can you drive the bus to where you are getting it foamed? do you have to do anything to the outside skin so that it doesn't warp? After the foaming is done do you have to replace the inside skin and rivot it back inplace or can you just put plywood back on the wall? how often does it need to be screwed to the ribs?
thanks
carl
mci9 |
John Biundo (Jbiundo) (67.112.121.112)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, November 20, 2002 - 4:32 pm: | |
Hi Carl,
There's an on-going debate about this. On one side are the folks who advocate that the combination of plywood inner skin, plus perhaps some bracing, can take the place of the original stress panels.
Others argue that the MCI gets its strength from the skin, and that removing this part of the STRUCTURE will result in a weakened bus.
Unfortunately, I don't think there's a clear cut answer. If you're like me, you'll take the conservative approach and re-install the inner skins. This is kind of a bummer, because these skins are a mess -- covered with gunk and a bit damaged from my none-too-gentle removal. If you're a little less risk averse, you might take your chances and leave them off.
I *HAVE* heard people relate stories about having no problems driving their buses without these inner panels during construction, mainly for the reason you cite: getting spray foamed. But again, these are second hand. In my case, I'm either going to have the spray foamer come to my house, or use a DIY kit.
You might check the Yahoo MCI group archives for quite a few discussions on this topic in the last 18 months.
Good luck,
John |
Peter Broadribb (Madbrit) (65.37.89.72)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, November 20, 2002 - 4:36 pm: | |
Don't personally know on the foaming but some have said if it gets too hot then the skin stretches and the foam hardens before the skin shrinks back causing a bowed effect. I suppose it depends upon the skill of the operator. Hosing the outside with water may help was a suggestion made a while back.
The metal skin inside is part of the structural integrity of the bus and should be replaced as you found it and with the correct rivets. Some have plywooded instead and are apparently ok. I was going to replace my metal and then plywood over it, but since I sold the bus I won't have to worry about it now...... LOL. |
Mallie (65.38.24.98)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, November 20, 2002 - 9:52 pm: | |
Carl,, I don't know about all conversions, but I took out a whole passel of windows, and only intend to put back 5. None now. That leaves a lot of skin over ribs, riveted on 2/3 inch centers, that was not there before. Far more strength than all the interior skin put together, not to mention that there is another 9 inches of height added into that new skin with the roof raise.
I would certainly not be afraid to drive mine to be foamed. And I am not going to replace the interior skin even after foam.
Mallie |
carl mci9 (66.144.52.102)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, November 21, 2002 - 12:11 pm: | |
I have another question that deals with foam insulation. I need to keep my windows in because of the painted murals that cover the windows.
has anyone that has left their windows in sprayed foamed over them where there will be inside walls?
Also how does one get the yahoo mci group that john talks about.
Thanks for all your help
carl
mci9 |
RJ Long (Rjlong) (24.127.74.29)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, November 21, 2002 - 1:58 pm: | |
Carl -
To access the Yahoo Group for MCI busnuts, here's the subscription link:
mci-bus-nuts-subscribe@yahoogroups.com
And in case you aren't aware, there are also groups for GMC, Eagle, etc. A whole BUNCH of bus groups, actually. . .
If you haven't already, you'll have to set up a Yahoo profile in order to join, but it's fairly painless - just be sure to scroll thru all the screens, and make sure you check and/or uncheck the various boxes.
HTH,
RJ
PD4106-2784
Fresno CA |
Tom Caffrey (Pvcces) (64.114.233.180)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, November 21, 2002 - 7:19 pm: | |
I have watched this topic with interest, but one thing that I haven't seen brought up yet is the toxicity of various foams in a fire.
I realize that the R value of figerglass is miserable, but I notice that at least some of the makers took some steps to keep it fairly high.
I'm refering to the practice of placing the fiberglass in waterproof bags. I expect that they were trying to keep it dry, since moisture will collect in the skin of these coaches even without a leak.
If very much water gets into the fiberglass, it's R value is bound to drop. In very cold climates, I would expect this to be a serious concern.
I have noticed that in the older coaches such as ours, there is no foam. In a number that have had fires, I see the fiberglass burned away and the aluminum melted, but no sign of foam.
Is there a nontoxic, non water absorbing foam available for these conversions? Can anyone clear this up for me?
Tom Caffrey PD4106-2576
Suncatcher |
FAST FRED (209.26.115.108)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, November 22, 2002 - 5:34 am: | |
Don't know about foam , my coach has sealed FG in vapor proof enclosures , from the factory.
But GRP is something I know about , and it BURNS like crazy.
On USCG boats the use of a "special"FR (Fire Retardant) (extra 5c a pound)resin is required to reduce the burn rate from 500 (cheapo resin) to a legal 100 , which is about what oak burns at.
Special additives reduce that to 10 for the industrial ductwork industry, at a very minor decrease (2%) in streignth.
The foam insulation burn rate is usually "fixed " by covering the foam to prevent any open flame getting to it.
Folks with old extension cords stuck in the foamed walls, are you sleeping well?
FAST FRED |
Gary Stadler (68.7.217.217)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, November 22, 2002 - 11:02 am: | |
Yeah, that one has me concerned too. Much as I like the McMaster foam that I put everywhere in my bus, I've noticed that I've gotta be VERY careful about welding around it. The stuff takes off and burns like like crazy if any glowing slag balls hit it, and the fumes are very toxic. A good whack with the welding glove is all it takes to extinguish it though.
But it's only where the foam's exposed directly to air that there's a problem, and then mostly where the foam has been "broken" or trimmed so there's opened cells exposed. So in a way, I'm not worried at all about wires buried within it.
For example, if I weld on an inner wall where there's foam between it and the outer wall, the foam will get hot and stink like crazy but since no air can get to it, it does not catch on fire. It "self-contains" it's own molten/charred little "pocket" and since no outside air can get in, it doesn't burn. Enough gases escape that it still smells bad but not enough to sustain combustion. BUT you have to be very alert, because if some of it catches and I don't get right on it, it has the potential to spread VERY quickly. A good lesson for any of you is to go to an RV scrapyard and look at the wrecks. What you'll find is that virtually EVERY one is burned, and if you look closely you'll see that it was the foam that usually did the burning/spreading of the fire. Scary. So it's something to be aware of in your design, how to cover the stuff properly to avoid fire-spread should one start in your rig.
Yeah I'm a bit scary, and it was very spooky to try this the first time; I still keep my nasty big CO2 extinguisher right next to me anytime I have to do this, but so far, quite a few welds later it's never been a problem.
So my take on it is that if foam is covered and not directly exposed to air and ignition at the same time, there won't be a problem.
It is however, the one thing that I like and dislike about my conversion. If I could have figured out how to get as good an insulating job with something non-flamible, I'd have done it. My first bus had a rule- "if it burns it doesn't go on the bus"... it was a nice conversion but ended up looking like a tank inside. Wood, foam, cloth, etc are very nice things to be able to work with in a conversion, and limiting myself to metal was....well... only once did I do that and not this time.... |
DaveD (206.47.206.62)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, November 22, 2002 - 12:25 pm: | |
There are two things I'm not sure about regarding foam. They are:
(1) the flame spread and toxicity in a fire situation, and
(2) the off-gassing that might occur from the foam under normal installed conditions.
The first could make the difference between a terrifying experience and fatality, the second might have long term health consequences.
Despite it's poorer insulting characteristics, fibreglas might be safer.
DaveD |
John Biundo (Jbiundo) (67.112.121.112)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, November 22, 2002 - 2:21 pm: | |
Gary,
I can't recall whether you mentioned it at the time (yeah, I'm too lazy right now to go search ;-) but even if you did, here goes: How much of the McMaster foam did you use? Do you know how to translate from "bus size" to quantity of foam? If I recall correctly, I've seen some of these products sold in "board feet", whatever the heck that is.
I have an MC 9 with 8" raised roof. I want, say 2-3" in the ceiling, 1-3/4" in the walls, and to fill the pockets under the floor (guessing that's roughly the equivalent of 1/2 the amount needed for one of the side walls). Any guess as to the quantity/size of kits I'll need?
Thanks,
John |
Gary Stadler (Boogiethecat) (68.7.217.217)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, November 22, 2002 - 4:11 pm: | |
John, I didn't really do any calcs... Consistant with my "style", I simply bought the big pak and started spraying. I'd say for sure if i'd have stuck with an even one inch thickness, it would have covered the whole bus, ceiling and walls, easily.
BUT I purposely made most of the roof almost 4" thick, and my walls are between an inch and two inches depending on where. Plus I screwed up one time and wasted a bunch because I forgot to purge the spray lines first, and learned the very hard way what i'ts like to clean up a MESS of part A that has no part B mixed with it! UGH...
So I ran out about 2/3's the way thru the job which I totally expected. Purchasing the next smaller kit finished it off perfectly. My guess for your bus would be two of the large kits, because like me you are wanting to go thicker and your bus is a bit bigger than mine.
The hardest thing to get a handle on is actually how thick it is as you're spraying. And every bit that you make too thick gets sawn or ground off so is waste. Luckily the design of my ribs and the quantity of them everywhere gave me a good gauge to reference by, so I kinda knew when to move on.
Oh yeah, one last hint, if you wear glasses, put cheepos on that you don't care about while you're spraying. The stuff sends teensy little particles of the stuff everywhere, and it seems to have an affinity for palstic lenses. Totally ruined my perscription lenses at the tune of over a hundred bucks. Drat! And use a fan that provides good ventilation and loads of fresh air to breathe. The stuff won't necessarily make you sick but it's a nasty smell!
I'm definitely happy I did it... in the desert in full sun just using 1 AC now keeps things reasonable inside. Turning them both on gets it downright cold....!
...And Dave, I don't perceive that outgassing of the cured foam is a health problem. I'd be a lot more worried about vinyl, paneling etc. Once the foam is cured properly it's very stable and odor free. Cured Urethanes are fairly low on the health-problem list as compared to products that contain formaldeheyde or vinyl compounds...
Cheers
Gary |
Dale MC8 (66.52.64.97)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, November 22, 2002 - 5:54 pm: | |
John, a board foot is 12" x 12" x 1".
HTH
Dale MC8 |
JimStacy (12.87.109.163)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, November 22, 2002 - 10:49 pm: | |
Don't forget, guys, there is a difference between "hot" spray foam and "cold" spray. The hot product has a higher R factor and different chemicals. Hot system requires pricey equipment with electrically heated hoses to keep product hot at the gun.
Hot foam is stronger, bonds better, and has a significantly higher R factor. Try to find someone in your area that sprays storage buildings such as apple or potato warhouses. The guys who spray hot tubs or conversion vans are usually pricey. FWIW
Jim Stacy |
John Biundo (Jbiundo) (67.112.121.112)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, November 23, 2002 - 1:43 am: | |
Guys - thanks for all the info and suggestions. Couldn't do this without y'all (even though the varied opinions often make me think even HARDER about my decisions - which is a good thing, I guess, 'cept for the headache ;-)
john |
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