ceiling insulation

[JohnEd]

Now your talk'in!

[garhawk]

hi oregon

my bus is also a 1989 rts by tmc.  to fill in the indentations on the ceiling and the sidewalls (both inside and outside the bus) it was easy enough to make templates and cut out 3/4" foam inserts for each of the cavaties.  a cheapy band saw was used with the table set at the proper angle for the edges.  that gave a snug fit.

this method brought the indentations level with the cross sections whereby larger sheets of 3/4" foam could be overlayed.  condensation will only form in places where new moisture laden air is allowed to enter.  pay close attention to fit and you'll have no moisture problem.  the very best insulation is dead air space.

gary t'berry
'89 rts 102 40er

[Oregonconversion]

I have been looking at different foams on ebay and other places and most have an R value of 4 to 6 for an inch of foam. Where can I find the really high quality stuff? I would like 9 or more.

[HighTechRedneck]

I haven't seen any that ran more than about R-6.5 per inch. 

The 2 inch rigid foam I got at Home Depot has an R-12 rating.  The 3/4" has a rating of R-4.5.   R-Max is slightly higher with 3/4" rated at R-5 and it has foil on one side which probably helps with radiant heat.  But I've also noticed that it seems more susceptible to moisture damage than the standard rigid foam.