Great stuff in ribs

[EricW]

I've seen people putting what appears to be great stuff in the ribs of the bus. Do you just shoot it down from the top and let it go down and wipe or cut excess? Any risk of great stuff expanding in a manner that would push out the ceiling from the rivets or anything like that?

[scootie]

No way! maybe you are joking? Maybe you didn't phrase that correctly.
the general idea as I understand it, (and partially did myself, is once your ceiling is removed, put some blue tape over the rivet holes and spray some in the channel via a rivet hole. let expand, and remove tape.
I guess it helps some, and should cut down on condensation too.

[Timelord]

Great stuff requires air and moisture to properly set. In an enclosed space like that, it will not fully set and, as I understand it, will cause metal destruction. The general consensus here has been to avoid great stuff, especially for enclosed spaces.

[Docsgsxr]

Timelord is right. You won't get proper cure from it.

Why not just dip a rag in tsp, clean it out, dip another rag in some rustoleum, pull it through, and let it dry. Those ribs aren't going to make any difference in insulation factor in the grand scheme of things. If you're worried about making sure it doesn't transfer heat and cold, fill it with silicone..........

[EricW]

Not super concerned. I put 1.5in foam board insulation between the outer skin and the seat rail part then I'm attaching 2x4s to the ribs. This means that there won't really be any insulation between the ribs and the plywood inside. I suppose I could always go get more insulation but that seems a little silly seeing as I'm keeping most of my windows. Idk any opinions? Maybe reflectix on the ribs just so there's something

[Docsgsxr]

Originally Posted by EricW

Not super concerned. I put 1.5in foam board insulation between the outer skin and the seat rail part then I'm attaching 2x4s to the ribs. This means that there won't really be any insulation between the ribs and the plywood inside. I suppose I could always go get more insulation but that seems a little silly seeing as I'm keeping most of my windows. Idk any opinions? Maybe reflectix on the ribs just so there's something

Go to the UPS store and get some styrofoam peanuts and cram'em in there!!

[aaronsb]

The ribs channel any moisture or leaks down their length and into the wall of the bus body, then out the drainholes along the body wall. I'd avoid spraying anything in those cavities except maybe some anti corrosion wax.

A layer of insulation over the ribs is the way to do it. At a minimum, acrylic foam insulation tape will greatly reduce the thermal bridging.

[EricW]

Originally Posted by aaronsb

The ribs channel any moisture or leaks down their length and into the wall of the bus body, then out the drainholes along the body wall. I'd avoid spraying anything in those cavities except maybe some anti corrosion wax.

A layer of insulation over the ribs is the way to do it. At a minimum, acrylic foam insulation tape will greatly reduce the thermal bridging.

Thanks. That's the info I was looking for. Maybe I'll do the tape as well as just throw another layer of maybe just some of that cheap white foam insulation rather than spending more on the good foam board. Otherwise I could just glue some scraps onto the ribs

[EastCoastCB]

Originally Posted by Timelord

Great stuff requires air and moisture to properly set. In an enclosed space like that, it will not fully set and, as I understand it, will cause metal destruction. The general consensus here has been to avoid great stuff, especially for enclosed spaces.

THIS^

[Sevier]

Originally Posted by aaronsb

The ribs channel any moisture or leaks down their length and into the wall of the bus body, then out the drainholes along the body wall. I'd avoid spraying anything in those cavities except maybe some anti corrosion wax.

A layer of insulation over the ribs is the way to do it. At a minimum, acrylic foam insulation tape will greatly reduce the thermal bridging.

Hello aaronsb -

Are you saying that we will find holes along the lower part of our bus wall, where it meets the floor, and we should not cover those up with a sealant? Leave them open to lets condensation drain out?

[EastCoastCB]

Originally Posted by Sevier

Hello aaronsb -

Are you saying that we will find holes along the lower part of our bus wall, where it meets the floor, and we should not cover those up with a sealant? Leave them open to lets condensation drain out?

that's what they're for.

[Sevier]

Originally Posted by EastCoastCB

that's what they're for.

Oh my god ... it took 9 straight hours today of reading about how to insulate a bus to stumble across that little fact. I had no idea, and I would have sealed up every little hole I found. I am so concerned, no matter how much I try to teach myself, that I will do this all wrong

[EastCoastCB]

Originally Posted by Sevier

Oh my god ... it took 9 straight hours today of reading about how to insulate a bus to stumble across that little fact. I had no idea, and I would have sealed up every little hole I found. I am so concerned, no matter how much I try to teach myself, that I will do this all wrong

Just do everything slow and be mindful. It'll all work out fine.
There's really no WRONG way... just better ways.

[creationsofmaria.com]

I’ve read about many people having trouble with thermal bridging through the ribs, and even condensation coming through the screws attached to their ribs. Even if a bus is insulated, as I understand it if there’s not about 1.5” layer of spray foam or equivalent insulation covering that rib to prevent thermal bridging to the inside of your living space, condensation will become inevitable. The source of info about 1.5 inches is from this video:

https://youtu.be/zCER7XJObHA

There’s been talk about the spray foam not curing inside the ribs and that makes sense, so I’ll share my method and hope it can help, or that y’all can pick it apart and teach me somethin! Lol. This is why I’m here

I have screws inside my bus instead of rivets, so I removed one screw every 20 inches. Since the hose of the spray foam (Great Stuff 3”) doesn’t fit inside of the screw hole, I drilled out the holes with a 5/16 drill bit to open them up so I could put the hose inside. I started filling the holes from the bottom of the ribs (from the floor) again starting roughly 20 inches up from the floor, closing the hole with a piece of blue tape FAST, making sure no air or foam is inside the tape (you can even use a magnet outside the tape for extra security- that works great!). If you start by doing the bottom holes, then covering the hole you went in from and letting JUST that cure fully, you’ll see it come up to the next hole when fully cured. The holes I drilled initially in the rib are giving enough air for the foam to cure, and since I’m drilling into them anyway for structural purposes I’m more worried about thermal bridging/condensation issues than letting the bus drain as it was meant to.

For thermal bridging between my ‘studs’ (plywood strips) and the metal, I’m about to purchase Echo Tape : https://echotape.com/products/fo-v23...k/?print=print

Everyone’s got different styles and budgets but since I don’t have the budget to spray foam the whole thing, I’m thinking this will help.

Thanks for the knowledge (I’m used to reading these threads but never posting!!)

Maria

[Byrd Scheit]

I put a mechanical dail and magnet on the roof of the bus before I sprayed foam into the hat channel. I'm pretty sure it only moved .001
I'll try to find the picture. Just make sure you dont have any water leaks first

[EastCoastCB]

Originally Posted by creationsofmaria.com

I’ve read about many people having trouble with thermal bridging through the ribs, and even condensation coming through the screws attached to their ribs. Even if a bus is insulated, as I understand it if there’s not about 1.5” layer of spray foam or equivalent insulation covering that rib to prevent thermal bridging to the inside of your living space, condensation will become inevitable. The source of info about 1.5 inches is from this video:

https://youtu.be/zCER7XJObHA

There’s been talk about the spray foam not curing inside the ribs and that makes sense, so I’ll share my method and hope it can help, or that y’all can pick it apart and teach me somethin! Lol. This is why I’m here

I have screws inside my bus instead of rivets, so I removed one screw every 20 inches. Since the hose of the spray foam (Great Stuff 3”) doesn’t fit inside of the screw hole, I drilled out the holes with a 5/16 drill bit to open them up so I could put the hose inside. I started filling the holes from the bottom of the ribs (from the floor) again starting roughly 20 inches up from the floor, closing the hole with a piece of blue tape FAST, making sure no air or foam is inside the tape (you can even use a magnet outside the tape for extra security- that works great!). If you start by doing the bottom holes, then covering the hole you went in from and letting JUST that cure fully, you’ll see it come up to the next hole when fully cured. The holes I drilled initially in the rib are giving enough air for the foam to cure, and since I’m drilling into them anyway for structural purposes I’m more worried about thermal bridging/condensation issues than letting the bus drain as it was meant to.

For thermal bridging between my ‘studs’ (plywood strips) and the metal, I’m about to purchase Echo Tape : https://echotape.com/products/fo-v23...k/?print=print

Everyone’s got different styles and budgets but since I don’t have the budget to spray foam the whole thing, I’m thinking this will help.

Thanks for the knowledge (I’m used to reading these threads but never posting!!)

Maria

Great stuff is going to start corroding inside those ribs a lot faster/harsher than you think.
I once used it on some steel in a confined area. About 6 years and it had eaten entirely through.

[DeMac]

I concur with ECCB
Great Stuff = Rust Accelerator
The Potential Risk Outweighs the Potential Benefits.


When removing the ceiling panels, we discovered that our ribs are already filled with insulation.

The IC/Navistar factory stuffs a strip of fiberglass insulation into the hollows of each rib, prior to installing the exterior skin. Visible in the photo below.


(IC Corp Factory Photo)

Sure, it's joined metal-to-metal & probably conducts, but there is no air pocket inside. No convection.

[creationsofmaria.com]

Thanks for the heads up guys!! I already did half the ribs (all ribs but only on the drivers side of the bus), now I’m wondering if I can combat the future rust at all from this point? It didn’t seem like there’s rust inside but now I’m nervous about it eating through the steel. Should I drill holes into the ribs every few inches so the great stuff is less enclosed?

Thanks for your input

Maria