To use or not reuse that is the question...

[Sirdave]

I have a couple of questions as I start my build, well more than a couple but first things first. I'm thinking of pulling the metal perforated ceiling down and doing the spray foam insulation and then putting it back up, is there a reason to not reuse the metal ceiling? Pros and Cons, besides it being a great place to keep my refrigerator magnet collection...lol And the next question because my bus is a rear engine should I keep the heater that's mid way in the bus and runs all the way to the front for the drivers heat? and if not what would I use for heat up front while traveling, also from what I've read here keeping that system gives me the ability to help cool down the engine if it starts running hot by opening up the system and allowing coolant to flow through the heater system.

[EastCoastCB]

I doubt you'd get it back up. Once it comes out its pretty much out.

[Scooternj]

Another con for attempting to reuse the ceiling is thermal bridging and condensation.

[Sirdave]

I had read people talking about the condensation but wasn't sure if the metal roof being perforated made any difference.

[EastCoastCB]

Yeah- buses sweat a LOT inside. The tin can effect. Check my thread if you wanna see what it was like under there.

[DoubleO7]

if your going to get condensation on the interior metal, your still going to get condensation if it is any other material.
Depending on what you end up using, you might not see it since it has soaked into or migrated to the next impermeable surface up.

As moisture evaps, it goes somewhere or nowhere it does not disappear on it's own.

[KashMoore31]

Originally Posted by Sirdave

I have a couple of questions as I start my build, well more than a couple but first things first. I'm thinking of pulling the metal perforated ceiling down and doing the spray foam insulation and then putting it back up, is there a reason to not reuse the metal ceiling? Pros and Cons, besides it being a great place to keep my refrigerator magnet collection...lol And the next question because my bus is a rear engine should I keep the heater that's mid way in the bus and runs all the way to the front for the drivers heat? and if not what would I use for heat up front while traveling, also from what I've read here keeping that system gives me the ability to help cool down the engine if it starts running hot by opening up the system and allowing coolant to flow through the heater system.

I had the same set up. Rear engine with heater midway. For the time being I removed the heater and ran the heater hoses under the bus to the front. I did that so I would have heat and defrost in the front. I hung on to the heater and may incorporate it back into my layout. Hope this helps...


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[AlleyCat67]

I have rear engine with TWO heaters between engine and driver. I'm not gonna worry about removing mine as I intend to integrate them into the design so I have heat going down the road when needed.

My front heater blower doesn't seem to be working though, I do need to figure that out before it gets cold..... defroster works well though so at least I'll be able to see out my windshield.

[Sirdave]

My heaters are so clogged with dust and dirt nothing comes out of them so first step will be tearing them apart and giving them a thorough cleaning, I don't think they got a lot of TLC during the years as a school bus.

[TAOLIK]

I reused one of my ceiling panels. Part of it was used to skin the drivers side window of my bus, the other part was used as a table topper for my shop table. But there is absolutely no way I felt willing to purchase and redrill 3,000 screws into prexisting holes in the ceiling while using my triceps to align a 30 pound piece of flexible sheet metal with those preexisting holes and drilling. 5 times? no thanks.

Benefit of the doubt though, as Tango has mentioned: A bluebird engineer stressed the importance of the inner sheets for the structural integrity of the bus. So your bus will be a lot more meteor/tree proof with the inner ceiling. I think either way it will still total any car foolish enough to hit you.

[Brad_SwiftFur]

Originally Posted by TAOLIK

Benefit of the doubt though, as Tango has mentioned: A bluebird engineer stressed the importance of the inner sheets for the structural integrity of the bus. So your bus will be a lot more meteor/tree proof with the inner ceiling. I think either way it will still total any car foolish enough to hit you.

Yes, the inner sheets do provide quite a bit of extra structural integrity to a bus. The same holds true for box, van, and refrigerated road trailers which have no frame.

Try taking a sheet of paper and folding it into a channel shape (3 sides, 2 "walls" and a "floor"). Support it on each end (like the axles on the front and rear) and place some weight in the center. It won't take much before it folds.
Now take a similar sheet of paper and fold it to have a box shape. Secure the seam with tape. Support both ends, and put some weight in the middle (inside). It will support much more than the channel did. The top gives the upper "walls" the support they need to keep from buckling. Road trailers work on exactly the same concept, and is why putting a concentrated load in the center can (and does) cause them to buckle. Our bus bodies use the same principle between the inner and outer skins (hence the reason for a bajillion screws or rivets). The entire body doesn't need this support, as our buses have full length frames to support the weight, but it does add a lot of rigidity to the whole structure.

RV's have very low crash standards, where school buses have very high crash standards, so if you remove the inner sheeting and don't replace it, I don't think anyone is going to make an ordeal of it. Most of us do have something covering our ceilings, and that does help offset the removed steel sheets ... and more to the point, most of us aren't carrying around a load of school kids, so even if the worst does happen, the roof isn't likely to flatten innocent kids (the interior is another matter!). The NTSB isn't likely to come knocking for a retired school bus that has been extensively modified (unless it was a defect from the original builder).

[Sirdave]

That's good information to know, I was definitely planning on covering the ceiling once I had the spray foam installed, just didn't know if I was going to try and reuse the perforated steel I took down or a nice luan or tongue and groove or... so many choices.

[DoubleO7]

I think I want to re-skin the ceiling of mine with maybe a "low wave" corrugated tin.
You can get it at pole barn steel suppliers cut to the exact length you want and only pay to the inch. And the corrugation allows you to follow the curvature of the ceiling without pre-forming.

[Geo Jeff]

Engineers and structure hmm I've met and worked with these so called individuals.

I was really hoping to put the back 24ft of panels back on? Are we thinking that's not going to happen? I was going to foam in there. Since its just going to be a work shop I thought the metal would be perfect and predrilled.

I thought it would go right back up there?

[AlleyCat67]

No reason it shouldn't but because of the size of the panels you'll want to recruit some help, or have enough bracing, to hold the panels in place until you get at least a few screws or rivets back in, enough to hold them up anyway.... one at each corner, one in the approximate middle of the bus, then one or two more on each side spaced about equally. Then you can put the others in on your own as you get time.

This of course assumes that the panels are in decent enough condition to be worth putting back up. If there were roof leaks and the insides of the panels are corroded, it wouldn't be worth the effort. You could use the corrugated tin panels like DoubleO7 mentioned, though of course you would have to drill the holes in those.

[DoubleO7]

Before I totally remove all the panels and pull out the skimpy cheap fiberglass....
I am at least going to try this:
Remove the (mine are screwed in) screws from one side plus some extras from the last panel installed. Then pull the loose end down towards the floor without bending or kinking the panel(s) and using some tie wire, secure the loose end to the floor. Enough of the panel from the loose end will be unscrewed so that I can get the crappy FG out.
If that ones goes well, do the rest the same way.
After running new wires, etc. reverse the process and resecure the panels.
All holes should line up to existing holes as lon as a dozen screws on one end of panels was not removed.
Either insulate as you go or inject expanding foam, blow in foam, etc. ?

Maybe.

I want to investigate this Aircrete stuff R3.9 per inch, foam into cavity does not push walls out from expansion, etc.
Home | Airkrete - All Green Spray Foam Insulation!

[TAOLIK]

Just to clarify something you're probably aware of. If you use one part expanding foam insulation, you'll want to make sure that it has proper air to cure. Otherwise there's been an incident or two of people using greatstuff improperly (such as spraying within the frame) and it corroding the metal. I forgot the build but there was one shortbus build where the ceiling was completely rusted/destroyed from improper use of spray foam.

Also your wire tie idea will probably work, but it may be good to look into if there are any cleco's that will temporarily fasten the ceiling. They will be much easier to use than tie-ing and untie-ing a wire tie.

[Sirdave]

Love the Airkrete idea looks like really good stuff, just not sure about overhead application, but something to look into for sure.

[DoubleO7]

Originally Posted by Sirdave

Love the Airkrete idea looks like really good stuff, just not sure about overhead application, but something to look into for sure.

I google "air krete pros and cons"
Seems it noticeably shrinks when even in 5 gal portions.
And is crumbly when cured.
Does not sound like it is that great after all.

Now leaning towards rock wool for walls and ceiling.

[EastCoastCB]

Originally Posted by DoubleO7

I google "air krete pros and cons"
Seems it noticeably shrinks when even in 5 gal portions.
And is crumbly when cured.
Does not sound like it is that great after all.

Now leaning towards rock wool for walls and ceiling.

I'm using rockwool in some walls. Interior walls especially since its completely fire proof and thus could help if such a calamity strikes. Its hydrophobic as well. Good stuff for certain applications.
Poly board will be used in the exterior walls and ceilings. I *MAY* do a bit of spray foaming, but I'm trying to keep this simple and cost effective.