I'm getting ready to do my ceiling and am looking for a material for a heat barrier and wondering what's being used out there. I was thinking of using rigid 1/2" insulation covered by 1/4" plywood, but is there anything less thick, say 1/4" that will be easier to install. What about 1/4" insulation used under siding installs. Any ideas besides green shag carpet? Thanks Gerry H
Check out the "Beginning From This Morning" YouTube channel. They did some head to head testing on this very subject and posted the results. I believe they are on one of the bus forums now as well.
I used 1 inch blue foam board. Joints with foam in can. Put foil bubble wrap below it. then furring strips to hold insulation in place. Did same on side walls. with Luan over all. Then covering of your choice. Used Marine vinyl on ceiling stappled and then reversed to sides. Don't forget floor /top of bays anywhere you can. I cool to 100 deg in sun and single digits for heat. two 9000 BTU and 1 each 12000 btu. 45 ft XLE. 8yrs with this set up. If you go to bus projects section 45XLE there are several pictures. Last post in 2018.
The Beginning From This Morning videos show something glued directly to the metal roof before the insulation. From their testing it helped enough to be worthwhile.
Check out EHP. Several bus people are using this now for their superior insulation value. It is probably the best insulation on the market. www.engineheatprotection.com
Read an article about using this insulation in the September issue of BCM.
https://www.busconversionmagazine.com/wp-content/uploads/2018/12/BCM-2018-09-Sep.pdf
Thanks for your input everyone, so far I like the CeraTex 3170 idea from Beginning from this morning, Thank you Richard.