Insulation questions

[Mex-Busnut]

Dear Friends,

I hope you guys and gals are not getting tired of my millions of questions!



Today my carpenter friend Beto and I went over to the Home Depot in our state capital, about 35 miles away, to locate some insulation for the bus. There was only one option, which was Owens Corning R-19 fiberglass rolls. It is the stuff that has the Pink Panther on it. We are planning to do a carefull sealing to waterproof the roof (We have the ceiling removed!).

1. Do I need to place some protection between this stuff and the engine, such as more sheet metal, or maybe the heavy tin foil stuff airconditioning people use on their ducts? (This will go under 5/8" plywood floor in the engine area.)

2. Does this stuff catch fire? If so, how do we protect it?

3. Does it need to be protected from humidity? How do we do that? The stuff we removed from the ceiling appeared to be very rotten.

4. My paint and body shop guy is suggesting adding some undercoating-type paint to the under-roof before putting in the fiberglass and the ceiling, to increase protection. Does this sound like a good idea?

Thanks in advance!

[robertglines1]

no foam board?  fiberglass gets wet= mush  will melt in fire.& burn must stay fluffy to = r value

[niles500]

A layer of 6 mil visqueen properly installed between the insulation and the finished ceiling/walls of the coach will isolate the water vapor to some extent - HTH

[Mex-Busnut]

no foam board?  fiberglass gets wet= mush  will melt in fire.& burn must stay fluffy to = r value

Yes, Bob: We also got 10 sheets of 4 by 8 foam board, but the R value is way down. So maybe put this foam board under the fiberglass, and seal it carefully against moisture?

[chev49]

I don't exactly reccomend this for a bus, but instead of plastic sheeting, i now use house wrap (like tyvek). I'm not getting into the mositure questions here, but i have used it while repairing a travel trailer.

[Dreamscape]

We used 1 1/2" closed cell roofing insulation, tar paper both sides. Then went over the top with 3/4" foil two sides from Lowes. It has worked very well and in this hot Texas heat, we stay mighty cool.

Check a roofing supplier, hoping you find one in your area.

If you check our blog, there is some information along with pictures. Go here http://www.uniquebusconversion.com/2008/11/these-pictures-show-installation-of.html

Note: We did ours before I even knew about bus boards! Might have done it differently, but it is what it is.

[robertglines1]

Biggest (one of) thing is the thermal break between the outside steel/alum skin and inside. that said ; make sure no metal is exposed to interior that it is all covered by insulation and or wood -a non heat/cold conductive material. Heavy shades or drapes for windows when not in use will help also.   Yes I no all material will conduct some heat or cold but at a lower rate.

[mike802]

I did a lot of research before deciding on which type of insulation to use on my conversion.  The conclusion was the fiberglass batting was out because of condensation getting it wet and ending up with absolutely no R value.  I didn't think I could totally eliminate condensation in a bus environment no matter how hard I tried.  The best choice is blown in expanding foam, but it only has a slight advantage in R value over pink, or blue board and cost a lot more.  I decided to go with Styrofoam board, packing in as much as possible and filling in any gaps and tightening it all up with expanding foam in a can. Now condensation is no longer a worry as far as R value is concerned.  I may have a little less R value than fiberglass and a little less than spray in expanding foam, but it's only about 1 or 2 R's.  Also take into consideration that huge hole in the front called a windshield, maybe the dash, or the whole front end depending on how difficult your particular bus is to insulate there, can you really take full advantage of the R value your insulation has to offer. Remember that R value is calculated in a laboratory setting under perfect condition, a bus does not even come close to that.  For me I feel I made the right choice for my budget and my intended use for the bus. 

[rampeyboy]

Regarding the foam board insulation, how do you attach it to the metal roof? What type adhesive?

Boyce

[Dreamscape]

A foam adhesive would work, won't burn through. Any hardware or box store has it.

[robertglines1]

tip   plastic sheet on some foam board will seperate from board and stay glued to roof without board. lesson learned  da   foam to metal 

[Just Dallas]

No one has bothered to mention that if you compress the fiberglas R-19 you'll lose the majority of your insulating value.
If you have an extra 6"+ in your ceiling for the fiberglas, you'll still be better off with foam board at R-7 per inch.. three inches would give you an R-21 rating, and as mentioned, seal all the seams and cracks with expanding foam insulation.
I went one step farther and used Reflectix between the finished ceiling and the foam board.
I could keep the front third of the bus cool with an 8Kbtu window air and a box fan when ambient was 85°

Do it your way, and good luck.

[rampeyboy]

Any preference to which foam board? I see some that are foil backed on both sides, some that are not lined on either side, and I think I saw one with a foam liner on one side only....

[robertglines1]

I like the most r-valve for thickness  which is either pink or blue.    The white bead board I stay away from.  The blue had the plastic on it. Removed it on one side and adhesive held to ceiling just fine.

[garhawk]

The best insulation in dead air space!

Build accordingly.