R value for interior insulation?

[grantgoold]

What are people trying to get in "R value" for their interior insulation. What is the R value of the spray insulation? Hard board or other forms of insulation used in bus conversions? I have the opportunity to use R21 insulation for the side walls of the bus. I was told that I could almost get 20 degrees cooler using this insulation.

Any ideas?

Thanks

Grant

[chazwood]

Two inches of the high quality closed-cell spray foam is R20.... not to mention quiet and stiff.

[Stan]

I haven't heard of the R10 foam. This is the more commonly accepted R value for foam coming from one manufacturer.

# Closed Cell Polyurethane Foam Insulation - Expands 8 to 1 for better control and less waste.
# R-7 Per Inch - Low perm rating makes it practically waterproof

[chazwood]

My friend, spraying mine, said they spray rooftops with it, in place of shingles.  Also said there were lots of different degrees of quality. All I know... is what they yell at me.

[grantgoold]

Thanks for the input. The product I have access to also comes attached to a 4X8 piece of plywood so I get a double bang for the buck. The product is used extensively to make commerical freezers and so forth.  It is supposed to absorb no water and so condensation/mold shouldn't be an issue.

I plan on making this material my interior side walls and the back wall of the rear cap. One person used the material on his boat and says he cannot believe the difference in both climate as well as sound.

Any thoughts?

Grant

[rcbishop]

Bottom line is.....how much glass does one have.....? ....makes a HUGE difference.

FWIW
RCB

[John Z]

I think infiltration is the most important issue in my bus. I am amazed at the number of air leaks yet after all this time.  It would not make much difference if the R value is 10 or 100. If your air leaks total up to the equivilent of having one or two windows open, all the expense of the extra R value is right (pardon this one) out the window!

[chazwood]

My walls and ceiling are stripped all the way to the outside skin. (waiting for foam) I walked around yesterday on a very pleasant sunny day and took some temp. readings with my death ray info blaster. (I get to use it when my kids lay it down) I still have all my OG windows. I was a little surprised to find that the ceiling metal was reading 78 and the tinted window glass read 102.

So, Yes, If you have loads of windows, all the foam in the world will only do so much.

[Tenor]

For extreme conditions, hot or cold, I'm thinking of using 4x8 sheets of that foam to make inserts for my side windows.  I'll also be making some heavy curtains for the front and door windows.  I was amazed at how much of a difference some old white thin curtains made on my old bus when hung over the windshield.  Don't forget the power of shade in the summer.  Awnings are a huge help.  I still have 10 feet of RV window where the old passenger windows were so my 19 ft awning will take care of one side, and I have a 17 Ft awning for the drivers side.  Not many people put the full size ones on the drivers side, but we camp in groups quite often, so it's nice to create extra party zones!

[Tom Y]

Grant, How do you plan to install them? Are you going to foam in between the supports first? How much space are you willing to give up to insulate? 2 iches per side? Just a thought.  I did not spray foam mine,but cut foam to fill in. Took way longer than I thought it would. I agree with most that having it sprayed is best.  Good luck.  Tom Y 

[grantgoold]

Tom, we plan the following; I have the entire interior stripped. We plan on placing the sheets of insulation up to the curve on the wall. This we hope will maximize the opportunity to insulate the bus. We are going to completely cover 8 of the 14 windows with this same material. The sheets will be held in place with screws that attach the plywood at the same location as the luggage rack and below at the wall connections for the seats. These two locations should provide enough securing to keep the plywood and insulation in place. We are also going cut out window holes that will be somewhat smaller than the original window openings.

Thanks

Grant

[rv_safetyman]

An alternative is the product from E.H.P.  They advertise in Bus Conversion.  Their website is:  http://engineheatprotection.com/rollboard.html

This is some amazing stuff, but quite pricey.  I used to be a dealer, but the demand did not justify keeping it in the line.

I have used the Rollboard for exhaust applications a couple of times and it works great!!  The website (and ad in BC) shows it being used used to insulate the interior of a bus. 

This subject has come up before on one of the boards, and I believe that someone pointed out that this product does not have an R rating and may not function well in this specific application.  I am a little weak (understatement? ) on the science of insulation, but I can't imagine that it would not do a great job.

I used foam board in the walls, but plan to use the Rollboard when I do the ceiling. 

Jim

[grantgoold]

Interesting stuff! I am not sure what I will do for the roof but this stuff looks like it has promise. I am picking up the board tomorrow and will try to keep a detailed photo albumn so others can see how it installs. I am getting this material at a great price ($12.50 per sheet). That is $16.00 cheaper than plywood at Lowes and the vendor says about 1/6 the price of the material shipped to me.

Have a good day.

Grant

[jackhartjr]

While we are in the very early stages of our conversion...I have done a lot of research on this subject.
We are going to bite the bullit and have it sprayed in.  Not only do you fill a lot of voids that you might miss with sheeting, I like the fact that you can then walk on the roof and it not move.  I like the strength of that.
Just my two-cents!
Jack

[HighTechRedneck]

An alternative is the product from E.H.P.  They advertise in Bus Conversion.  Their website is:  http://engineheatprotection.com/rollboard.html

This is some amazing stuff, but quite pricey.  I used to be a dealer, but the demand did not justify keeping it in the line.

I have used the Rollboard for exhaust applications a couple of times and it works great!!  The website (and ad in BC) shows it being used used to insulate the interior of a bus. 

This subject has come up before on one of the boards, and I believe that someone pointed out that this product does not have an R rating and may not function well in this specific application.  I am a little weak (understatement? ) on the science of insulation, but I can't imagine that it would not do a great job.

I used foam board in the walls, but plan to use the Rollboard when I do the ceiling. 

Jim

Looks interesting, but at 3 times the price per square foot of rigid foam, I sure would want to see more documentation on the insulating value.  Their is suprisingly little specification data on their site.  For me, it is a moot point anyway since I have already insulated and am quite happy with the rigid foam I used.  That said, if I ever do another one and had the budget, I would probably go with spray foam.