Spray foam and riveted ceiling panels

[Maddie-SKO]

First, I know this is not the best way to do it. For a long list of reasons the best ways aren’t available or possible, this might be. The bus is already converted and it’s where we live full time.
Second, I know that by not doing insert-thing-here I’ll still have air and thermal leaks and whatever else. For a long list of reasons I can’t address those right now.
Third, I’m mostly interested with making an improvement over not doing anything, even if it isn’t ideal or perfect.

I am looking to gain risk awareness around how I’m thinking of doing ceiling insulation.

I have a 2006 international skoolie. Removing the light and speaker rails there are holes where the wires were run and I can see whatever the stock insulation was. Water got into the roof so I want to remove the current insulation through those holes and a few others. I likely won’t get all of it but I’m hoping to get a majority of it. The ceiling is riveted and perforated and per the first two points they can’t come down.

I’m wondering what risks I should be aware of (health/safety) if I remove the stock insulation this way and then use spray foam insulation through those existing holes. I know there will be air leaks from other parts of the bus, and that I likely won’t get an evenly distributed spray as if I took the panels down but like I said in point 3, im just looking for an improvement vs doing nothing.

 

[TaliaDPerkins]

Hi, by this . . .

by not doing insert-thing-here I’ll still have air and thermal leaks and whatever else

Do you mean the spray foam with riveted panels over it are already in place?


Why would there be huge thermal and air leaks?

 

[Maddie-SKO]

Do you mean the spray foam with riveted panels over it are already in place?


Why would there be huge thermal and air leaks?

The riveted panels are already in place, and the bus had been “converted” by previous owners. My goal would be to spray foam in the gap between the perforated ceiling panels and the bus roof.

Air leaks was just something people mentioned last time I asked as a way to say “why bother”

 

[Red_Fir]

FWIW.
The problem with not going down to base and building out is rust, ... any that's started will continue.
But, first ensure its dry (as in do this in August).
Old insulation is not biological materiel it will not contribute to mold, ... but it will harbor it.
Make a race out of plywood, 2x's and Plexiglas the same length and width and depth as the void you are trying to fill. Using 3/8 vinyl hose and high expansion open cell foam measure how long it takes to fill the hose, and how slowly you need to pull the hose out of the void to ensure complete fill.
Drill a half inch hole inside the bus at either end of the void you wish to fill, using two electrician's fish tapes from both ends (a hook on one and a small tangle of string on the other) pull a length of 3/8 vinyl hose through the void, plug the far end of the void after the hose is in place, shake up your foam, connect it to the hose, have a friend operate the trigger and can, while you, using a stop watch and sharpie reference lines on the hose pull it back at the measured rate.
If the voids are not continuous you should figure it out on the first attempt to fish.
A couple of caveats!... While everyone makes a great fuss over foam very few foams are flame resistant, many burn like gasoline once lit and the smoke from all of them is toxic as ****!, there's a reason fiberglass retains its preeminent position in insulation.
Also while you're experimenting it might be worthwhile to see if you could (using a slightly larger hose (1"?)) use blown cellulose rather than foam as this can be rendered flame resistant, and far less toxic if lit.
Here's an article addressing flammability and toxicity:
https://timberhomesllc.com/cellulose-fire-safety-and-health-concerns-of-flame-retardants/