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Old 01-14-2021, 05:28 AM   #1
Join Date: Jan 2021
Location: Oregon Coast
Posts: 13
Year: 1987
Chassis: Ford E150
Engine: Diesel
Advice on insulating shuttle bus


This is my first post, and I am hoping somebody will be able to provide some good advice on how to insulate my shuttle bus. I've watched a ton of conversions online and there are so many different ways to do it -- I'm not sure what is right for me and my area.

First, the bus has a wood floor, not metal like a lot of the buses. It has a fiberglass ceiling with metal framing. The walls are fiberglass with metal patched areas. There are also some wood patches inside the fiberglass (such as around the window in image 1).

1. There is quite a bit of rust on the metal. It seems like I should treat it with a rust converter first. There is a lot of old glue on it also, but I would like to not have to sand all of that off if I don't have to just to save time and effort since it will be covered up. Does that sound OK?

2. I live where it rains a LOT, and there is a ton of condensation from the metal. Every day I empty a dehumidifier that fills up. I know the insulation is supposed to stop this from happening in general, but should I install a vapor barrier? I have seen yes and no on this -- yes you need it or no it will trap moisture because nothing is every perfectly sealed.

Or is it just enough to have a thermal break on the metal parts. I saw somebody cover the metal strips with sill seal before adding walls. I saw somebody adding furring strip over the metal before adding walls. Somebody else added CeraTex over the metal.

For full vapor barrier, I saw somebody use a shiny metallic vapor barrier as the first layer below the others (this was a new metal floor, though). Another person painted the wood subfloor on both sides with Kilz (a replacement wooden subfloor).

Hence, my confusion. I plan on going to fairly warm climates, but again it will be stored in a wet and cold (not freezing) world at home, so I want it to withstand the falls/winters.

3. I've seen people use 2x2s and 2x4s to build up the floor and add the insulation boards between the wood. Then I read that this is not necessary and that the insulation could be put straight down and the plywood put over it. The large plywood pieces will spread the weight distribution so that the insulation doesn't get compressed. This seems like a time saver. Is it your experience that this is fine to do? Or is the thicker wood needed to have something to screw the plywood into?

4. For the main floor insulation, I was just going to go with the rigid foam.

5. In image 6, you can see that the floor in front of the lift doors is not in the best shape. There is water damage, but the wood is not flaking off or anything. So I'm hoping I don't need to replace it, but instead I can just go over it.

6. The previous owner glued up pieces of regular styrofoam on the ceiling (images 3 and 4). Is it OK to leave it there and just add real insulation on top of it? Or should I tear it out first? I don't know how much R value I will lose or if it will make much of a difference.

7. The lift doors are pretty thin. They are metal on the outside. Besides adding foam insulation in the panels, is there anything else I can do to help it without interfering with the functionality? I hate the doors themselves, but I like having the doors because I want to have an open air feeling.

8. Should I rip out the extra wood pieces, such as in images 1 and 2? Are they likely for support? or maybe I can just replace them with insulation?

Any help you can give is greatly appreciated. I just want to do this right the first time.

Thank you!
Attached Thumbnails
1-wall-detail.jpg   2-wheel-well.jpg   3-ceiling.jpg   4-ceiling-detail.jpg   5-floor.jpg  

6-floor-by-lift-doors.jpg   7-lift-doors.jpg  

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Old 01-14-2021, 09:37 AM   #2
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Phatman's Avatar
Join Date: Jan 2015
Location: Brazoria County, Texas
Posts: 819
Year: 1997
Coachwork: Carpenter
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Rated Cap: 32 Passenger
Try filling out your profile info so others can help with where you are at. Somebody in south Texas is a lot different than those in Pennsylvania.
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Old 01-14-2021, 10:33 AM   #3
Bus Crazy
Join Date: Apr 2020
Location: Northern California (Sacramento)
Posts: 1,473
Year: 1999
Coachwork: El Dorado Fiberglass
Chassis: Ford E450
Engine: V10 Gas
I'd research house construction best practices in your area to glean any tips they may have. I'm guessing a vapor barrier is highly recommended. In wet climates the dew point is going to be closer to the current air temperature, so condensation is more likely, even with small fluctuations of air temperature.

A vapor barrier prevents moisture in the air on the inside of the bus from reaching the bus skin. As long as there is some insulation between the vapor barrier and the exterior skin of the bus, condensation should be minimal. The more insulation you have, the fewer thermal bridges you have, the better.

Here's what I imagine is happening with your bus: as the outside air temp cycles, the bus skin follows very closely; but the air temperature inside the bus follows with a delay. Condensation occurs with falling temps, when the temperature differential is enough for the inside air near the exterior skin to reach dew point.

One other thought: putting a small space heater in the bus may help the inside air hold that moisture, rather than trying to squeeze it all out with a dehumidifier. It would be an interesting experiment at least.
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Old 01-14-2021, 11:06 PM   #4
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Join Date: Oct 2020
Location: Florida
Posts: 1,589
Coachwork: Integrated Coach Corp.
Chassis: RE-300 42ft
Engine: 466ci
Rated Cap: 90
Everything Rucker wrote, I second.
Dew point issue.
I'd follow Phatman's profile suggestion, too.

Your fiberglass body will probably an easier task than our steel tubes.

CCR, not the band

Imagine an ice cold beverage in a warm space. The beads of sweat cannot be stopped by a thin layer of anything. Foam coosy, yes.
Thats Conduction

Leave the fridge cracked just a wee lit'l bit. Cold front meets warm front, Sweaty fridge interior.
That's convection.

A cars wet ac vent on a hot sunny dashboard.
Thats radiation.

Consider how to battle all three and/or lower the relative humidiy of the interior air.

Edit: Its well worth your time to study the Rusty87 interior build out.
Ceiling: Framing & Electrical Rough-in
Convert Hatch to AC & Roof Patch
🇺🇸 Frederick Douglass: "If there is no struggle, there is no progress.Ē
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Old 01-15-2021, 03:55 AM   #5
Join Date: Jan 2021
Location: Oregon Coast
Posts: 13
Year: 1987
Chassis: Ford E150
Engine: Diesel
Originally Posted by Phatman View Post
Try filling out your profile info so others can help with where you are at. Somebody in south Texas is a lot different than those in Pennsylvania.
Thanks for the good suggestion. I filled out what I know.
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Old 01-15-2021, 04:08 AM   #6
Join Date: Jan 2021
Location: Oregon Coast
Posts: 13
Year: 1987
Chassis: Ford E150
Engine: Diesel
Thank you all for your advice. I'm working my way through the Rusty87 thread. Luckily I don't have such a rusty situation as that.

Here are some photos of the bus for a better overall view.

Attached Thumbnails
driver side.jpg   passenger side.jpg   front and side.jpg   inside front.jpg   inside back.jpg  

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insulation, shuttle bus, thermal break, vapor barrier

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