Is Biobased closed-cell soybean oil based spray foam OK for bus?

[Kevin Warnock]

Hello,

I have my 1994 RTS with Series 50 totally stripped and ready for the insulation. I got a quote today to spray 500 square feet to a 2" depth from a local spray foam contractor, who will spray my bus inside their heated building.

The salesman is recommending using a soybean derived closed-cell foam to do this job. He said it's the same price as petroleum based spray foam, which they are also willing to use at the same price. But the salesman recommends the soy based product because he says it's safer and better for the environment. They have been spraying this new foam for four months, and have what he said was an exclusive license for the area from the manufacturer.

Here's the datasheet:

http://www.biobased.net/products/prod_info_1701.pdf

The website for the manufacturer of this foam is:

http://www.biobased.net/

The R Value is 5.5 per inch. Is that good? I am thinking about having 2" on the walls the 3" on the ceiling, which would cost only 50 cents a square foot more for the part sprayed to 3". That would give me R 16.5 on the ceiling and R 11 on the walls.

The contractor I got the quote from has a guy who has done vehicles before. The salesman is so interested in my project he said he will attend the spraying to watch.

The fixed price he quoted in writing is $1,400. Does that sound OK?

My question is should I go with this newer 'green' product, or stick with the old petroleum based foam? One concern I have is that the data sheet says the highest service temp is 180 degrees F. Will the outside metal of the bus get hotter than that on hot days where it can get over 100 out? I don't often travel to such hot places, but I don't want to melt the insulation if I get caught in a hot location.

He said I will be able to press my finger into the dry insulation. I had been led to believe that you can't do that with closed-cell petroleum based spray foam. He said it will be about as firm as the rigid foil backed foam sheets you get at Home Depot.

He also said with the soy based product that they can spray it so accurately he won't need to trim it, but can still spray to the wood blocks I have in place to screw things to later. That sounds unlikely, but it also sounds easy to trim with a knife.

Any comments?

Thanks!

[steve5B]

Reading your post, I thought CLOSED CELL is the real hard spray foam.  I need to have mine done also but the price here where I live (Indianapolis)  was about half the price of what they gave you. I've have the same size bus, 1975 5B.  Maybe it's the type!

Good luck!

Steve 5B....

[Tony LEE]

I assume you will be driving the bus with all the inside wall lining stripped off.

Given the warnings that this is structural and that the body should be blocked up to prevent sagging when it is temporarily removed during conversion, can anyone comment on whether this cation applies to a 5A.

[RTS/Daytona]

I believe there is an easier and less costly way to insulate an RTS - I have first hand experience

using a cheap Harbor Freight spray gum / and Rmax foam insulation panels (available at most big building contractor supply stores)

see--> http://www.rmaxinc.com/Rmatt-3%2005-07.pdf      ---  guess what --> R-Valve 6.4 per inch  Plus foil backing to reflect heat

The trick is to fill the spray gun with contact cement and never let it seat empty overnight - and allows pull the trigger half way (air only) before you store it in a plastic bag - It can stay usable over a year - I spray with 80-100 PSI air pressure - comes out like cotton candy - I open all the windows and put in box window fans to blow out the fumes - yes I use solvent based contact cement - you only do sections at a time anyway not much vapor - I always wear a mask - no flames or spark sources

shoot a small section of the ceiling with contact cement - shoot a piece of foam - touch the 2 together - it will stick like crazy - use a rubber mallet and a small 2 x 4 to tap the surface into the curve of the roof / sides / corners - use strips to make it easy

#1 - the ceiling dimples in an RTS are 3/4" depressions - Just made for 3/4" Rmax (or similar insulation)

#2 - once the dimples are filled - that leaves a perfect 3/4" depression up to the 5' S/S frame members - perfect for another layer of 3/4" Rmax strips / pieces

#3 - continue the process for as many layer as you wish - I used four  2 x 4's  running front to back to form twin "ducted A/C" channels (1.5" x 8") and provide for 2 more layers of 3/4" rmax in the non-duct areas - I also added a 2 x 3's (with the 2.5" side secured to the frame every 5' with rivit-nuts to provide mounting for all my overhead cabinets 

#4 - the side are done the same way - use furing strips to block out sections and provide material to be mailed to when you do the walls

#4 - done - no shaving - no fuss - no mus  - HELL OF LOT LESS COST - BETTER R-Valve + Foil Reflection

#5 - Driving in my RTS is like riding in a THERMOS BOTTLE

any questions call me -- ***386**672*0571***

Pete RTS/Daytona

[TomC]

I had mine done in 1995 for $1600 for the petroleum based stuff that is really stinky until cured.  I swear by it, so $1400 now is a bargain.  Good Luck, TomC

[Tenor]

The petroleum based stuff has an  "R" factor of 7. something.  Mine did not stink after about 2 hours.  It needs to set for a little while before you drive anyway.  For about the same footage based on 1.5 inches, I paid $600.  Are you planning on having it really mounded over and then shave back to stud height or have them shoot to be as close as possible to the right depth?  Less waste that way, but maye less insulation.  Just something to consider. 

[buswarrior]

Spray foam is a great thing for a bus conversion on two fronts:

A nice R value, and, perhaps more importantly, it seals up all the little places for air infiltration.

All the insulation in the world doesn't help you as much as stopping the wind from blowing through the cracks.

Letting the inside air escape/outside air intrude is the biggest challenge to improving a vehicle's (or a house's) HVAC efficiency. In our old buses, every seam on the outside skins is a source of air infiltration.
Seal it up on the inside, job is done.

A coach with a lot more loose insulation can lose more heat/ac than one with a lot less but that is sealed up tighter. The outside air is able to mingle deep into or around the loose insulation, partially defeating the insulating goal. Spray foam seals up the skins, preventing that inside/outside air swapping in the walls/ceiling.

Don't be too concerned about leaving the spray just a little shy of your finished building surface in a few places, the fact you've got it sealed up is the best part, less work to get it trimmed back is good, and the fraction of an inch loss in R is pretty much a non-issue.

Also, efforts around the windows, and the bus front end, (defroster, holes under the driver, loose front skins) to slow up air infiltration yield good results. In the heating season, the roof airs are terrible for letting out your heat. A circle of velcro and a nice quilted cover from underneath would help.

happy coaching!
buswarrior

[tekebird]

my concern with the Bio based stuff is bio base stuff degrades because it is Bio Based....Bio Degradable.......thus is safer for the environement.....

but we all know they best stuff causes cancer, global warming etc.........or taste better....LOL from the food side.

I'd go for the petro stuff if it were my bus and money

[HighTechRedneck]

my concern with the Bio based stuff is bio base stuff degrades because it is Bio Based....Bio Degradable.......thus is safer for the environement.....

but we all know they best stuff causes cancer, global warming etc.........or taste better....LOL from the food side.

I'd go for the petro stuff if it were my bus and money

Excellent point.  I wonder what the long term effects of humidity or, worse, water leaks, would be on the bio version.  Consider packing peanuts. The traditional ones are an environmental hazard because they virtually never decay.  On the other hand, the biodegradable corn starch peanuts disolve almost instantly in water and shrink almost 50% from humidity in the air in just about 3 months.  In the case of a bus conversion, being around forever is a good think in my opinion.

[HB of CJ]

Sound OK to me, but then what do I know.  Only consideration would be that over a long period of time, it may not stick well enough to whatever it was sprayed/bonded onto and that it would pop loose from all the accumulated vibration/shocks/bumps a coach would endure.  Also another poster addressed the possible bio-de-gradeable nature of the stuff which I had not thought of.  Your call.