Old Spray Foam Removal From Fiberglass Shuttle Bus

[espanaheather]

My wife and I are working on a 2003 Ford E-350 shuttle bus. It was used for transport along the Oregon coast, which means rust. We got it via government auction for a steal, but it needs a lot of baseline work before we can even think about building.

Here is our dilemma: we discovered very badly applied (but strongly adhered) spray foam when we ripped out the walls and ceiling. We actually want to use Havelock Wool insulation when we get to that stage, but first all this foam has to go. We need to properly treat the water damage that happened on the walls behind it, as well as use rust converter on the whole frame. None of that can happen until the spray foam is out.

There are a variety of surfaces behind the foam. Thin wood veneer covering the fiberglass, random metal in some areas, and in other areas (like the ceiling) it's just the fiberglass shell itself. We have been using an oscillating multi-tool to cut through the foam at the edges, and then a rigid paint scraper to pull the foam out by chunks. This works to some extent, but only in the areas with the wood veneer. There's still tons of spray foam in crevices we can't get to, and adhered to the metal framework, and the ceiling. We know pure acetone can dissolve spray foam, but it seems like spraying the entire interior with pure acetone isn't a very practical solution.

Has anyone dealt with this type of spray foam removal? Would you stick with this mess of a bus, or cut and run LOL? We would love any tips. It would be great to just dry ice blast all of it out, which would simultaneously prep our rusty surfaces too, but dry ice blasting is super expensive. We're on a tight budget.

PS No idea why all my photos incorrectly rotated after upload, but the spray foam is on the walls and ceiling, not the floor as it appears at first glance.

 

[Meathead]

It looks like you have some thin areas in the foam, but if it’s stuck well to fiberglass, why not add to it instead of pulling it all out? Foam decreases vibration and strengthens the roof(for walking). The add material does not have to be more foam. Many of us have several different insulating materials in our buses.

Peace

 

[Rucker]

And, closed cell foam will not give you condensation issues like you may have with rock wool.

I second the suggestion to leave in place what already is there, unless you have to get behind it for work.

 

[espanaheather]

Hell no to spray foam.

We DO have to get behind all the existing spray foam to work. Words cannot express how much we abhor spray foam, and we will not be keeping a single bit of it. It traps moisture which then has nowhere to go. It is because of the spray foam that we are having to rip all of it out, because water stayed trapped behind it, which rusted out our frame and rotted all the veneer behind it.

We've decided to replace the rotted veneer with a specific cork underlayment, to provide both rigidity and a thermal break.

 

[JamesKS]

That sure sucks it has to come out! I would try the acetone in a pump sprayer. Respirator, suit and goggles if you get serious. Start in a small area and see what it does, you may be able to get away with diluting it and saving some coin. I am not sure what kind of sticky mess would be waiting for you though. Maybe a light hit of the acetone helps it break the seal and you could remove the rest by hand easier? Good luck!

 

[espanaheather]

Thanks so much James! Yea, we will be giving acetone a try in the areas where the spray foam is super adhered. I think we've figured out a decent way of getting it off the larger, flat areas now thankfully. And yes, goggles and respirators all the way! We're using our oscillating multi-tool to cut around the edges, and then a rigid paint scraper to pull the foam out in pretty big chunks.

The main area of concern now is the fiberglass headliner cap, which is spray foamed like crazy, including over all the conduit that contains the wiring for some of the lights. The walls are super curved, so we're looking at different tool options to get the spray foam out without damaging the cap.

 

[ol trunt]

I'm not saying acetone won't remove spray foam, I'd just say I can't think of a better way to turn a bus into a bomb than to pump spray acetone into such an air filled enclosed space. All it would take for detonation would be a single spark--like occurs in the ignition switch when it is turned on or off. Another great way would be to suck an acetone air mixture through the fan motor being used to clear the fumes.

I don't worry about spray foam but if I did I'd have made sure the bus didn't have any before I bought it. Oh well, can't think of everything.

A wire brush and a paint scraper are probably the best tools to use to remove the foam. I sure don't envy the task.

I don't know if it really works but I keep one of these handy and punch it every time I get myself into a bind and it makes me feel better.
Jack

.

 

[musigenesis]

I'm not sure this would work (and it would probably be even more dangerous than what ol trunt is warning you about), but I recently damaged the XPS foam board on my floor by accidentally spilling a small amount of gasoline on it; I was surprised at how much foam was eaten away by the small amount of gas. The gas sort of melts it down into a very thin layer of solid plastic and then evaporates. Rather than trying to spray it on, I would try painting gas on the foam lightly with a chip brush and see what happens. All windows and doors open, of course.

 

[Bus'n it]

Interesting thought Jack. I hadn't thunk of that myself. Either way, if it blew, he could just get a new bus and not have to work so hard ! (Just being funny OP!) Absolutely take precautions to keep it aired out and don't soak the living $hit out of it.

 

[Rucker]

We DO have to get behind all the existing spray foam to work. Words cannot express how much we abhor spray foam, and we will not be keeping a single bit of it. It traps moisture which then has nowhere to go. It is because of the spray foam that we are having to rip all of it out, because water stayed trapped behind it, which rusted out our frame and rotted all the veneer behind it.

We've decided to replace the rotted veneer with a specific cork underlayment, to provide both rigidity and a thermal break.

Is it possible the moisture is condensation, not leakage? Closed cell foam will prevent the water vapor from penetrating these spaces, so if you have tightly adhered closed cell foam, and there's water behind, that water would seem to be more likely from a leak.

Feel free to share pictures...

 

[Meathead]

It sounds like you just don’t like foam, period. Okay, cut it out like you are doing. There is a blade for your oscillating tool that has no teeth. Cut the foam like a pan of brownies and use the toothless blade to scoop under foam and lift out the brownies. Then zap what you can’t get to with chemicals.

Hmm suddenly I’m hungry [emoji39] .

Peace

 

[JamesKS]

Very fair points about the sprayer. In my head all the windows and doors were open. Since you mention it, disconnecting the battery would be smart. I think the brush idea would be safer and a better idea.

 

[Oscar1]

Sell the bus to someone that wants spray insulation and buy the bus you should have bought, one without spray insulation. If you hate spray foam as much as you say you do you will never be happy because you will not get it all out.
And please listen to Jack, you do not want to be pumping large volumes of acetone in there ever. It's rusty and has foam, get rid of it and start over.
Good luck, stay safe.

 

[peterbylt]

A number of years ago I had to remove an 85 gas tank out of a Boat that had been sealed in with a lot of Spray Foam.

We used a very high pressure, pressure washer, it cut through the spray foam like a hot knife through butter, had the tank out in about 15 minutes.

Peter

 

[Rucker]

We DO have to get behind all the existing spray foam to work. Words cannot express how much we abhor spray foam, and we will not be keeping a single bit of it. It traps moisture which then has nowhere to go. It is because of the spray foam that we are having to rip all of it out, because water stayed trapped behind it, which rusted out our frame and rotted all the veneer behind it.

We've decided to replace the rotted veneer with a specific cork underlayment, to provide both rigidity and a thermal break.

I noticed someone elsewhere in this site is using a needle scaler (air powered) to great effect on rust. Probably the right tool for spray foam insulation.

 

[BeNimble]

I don't think acetone will actually dissolve spray foam, nothing will, it has to be mechanically removed, and it will likely damage whatever it is attached to when removing it mechanically.

I agree with the advice to sell the bus and get another one if the foam is evil to you.
If it was a bargain, you should be able to sell it easily, with all the seats removed, and confirmed insulation already in it.

I don't quite understand how the spray foam in the ceiling made your frame rust??