How short do you need to be to ride this bus?

[ManWithNoBrows]

Does anyone know the maximum height a person can be to stand up in a Skoolie without a roof raise? I know roofs can be 6 foot or 6.5 foot, but I want to know a general rule of thumb on how much space I'll lose with a floor and shiplap ceiling.

[TheHubbardBus]

There is no standard way to build a floor or ceiling, and you'll find countless variations of either in the build threads here. Their respective depths are a variable you'll have to determine based on wants/needs. Also, I'm no expert, but I'm guessing there are more variations in gutted floor-to-roof height than the two you listed. Finally, make sure you account for the fact that being able to stand up straight in the middle of the bus does not equate to standing up straight anywhere else. Your layout of the bus will determined in part - and in part be determined by - how much headroom you need in various areas.

[RamRod4]

I'm 6' tall and we have a 6.5' interior height bus (Amtran/International).

3/4" XPS foam inuslation under subfloor
5/8" Plywood subfloor

Roof insulation is 1.5" XPS foam but it is between the roof ribbing so its not a net loss for ceiling height.

1/4" Cedar plank T&G ceiling
3/8" Nailers under cedar plank (this may change).

Total loss of interior height is ~ 2"

Keep in mind that these measurements are at the highest point of the ceiling in the center aisle.

[musigenesis]

My bus was originally 6'7" from metal floor to ceiling. My subfloor is 2" of XPS and 3/4" of plywood (plus another 1/8" or so of vinyl flooring eventually); ceiling is 1.5" XPS packed between the ribs plus an additional layer of 3/4" XPS and 3/16" plywood, so my floor-to-ceiling height is now 6'3". I'm 6'0" tall and I feel that 6'3" is the absolute minimum ceiling height I can have while walking normally inside my bus.

The majority of school buses are more like 6'1" or 6'2", so with similar insulation to mine you would need to be around 5'7" or shorter to get away without a roof raise (and shiplap ceiling will be about 1/2" thicker than my ceiling plywood). You can go with less insulation on the floor, but even using 1" XPS instead of 2" XPS only nets you 1" of extra ceiling height (and colder footsies).

These measurements also only work if you do a center-aisle (or "bowling alley") layout in your bus - the headroom at the edges will be 5 or 6 inches less thanks to the roof curvature (Thomas C2s have somewhat flatter roofs and also have high ceilings to begin with, around 6'7" as well). The center-aisle layout seems fairly unpopular in skoolies, although I personally think it's just a natural engineering solution to the height problem.

[ManWithNoBrows]

Hi guys. Thanks for your input. I'm 5'6" so while I always figured I'd fit, it's great to know that 6' people can stand up straight in the middle. While I don't think I'll have any issues with the height, I plan to work the height factor in for a 6' person and that way when I sell it someday, I'll have a better shot.

I'm also planning to stay away from foam board and spray foam because they're flammable, and instead go with fiberglass insulation, even if the thinner areas will have a bit lower R value. The wooden bits will get Fire Tect sprayed all over them to protect them for a few years in case of a fire. That way while the inside might have a fire somewhere, it'll start relatively localized while the Elide fireball explodes to extinguish it (utility closet) or I spray my CO2 fire extinguisher at it (living areas).

My plans won't prevent all potential fire damage that could happen, but fiberglass insulation is one of the important safety measures I'm planning on since it's all over the shell of the house.

If anyone has ideas on how to beef up the R value of a thinner layer of fiberglass insulation, I'd appreciate it. (Thinsulate sprayed with Fire Tect perhaps?)

[HamSkoolie]

Our 96 AmTran was about 6'5" at the center. After pulling the flooring and ceiling it's even more. We will be installing 1" foam under 1/2" ply and 1/4" or less finish flooring. Ceiling will be the original metal or 1/8" sheeting.
I'm 6'1" and should be fine in the center. However, in the bed area (rear of bus) it would have been nice to have had a 1' raise.....but we're willing to deal with that to avoid the hassle of a raise.

[RamRod4]

Originally Posted by ManWithNoBrows

Hi guys. Thanks for your input. I'm 5'6" so while I always figured I'd fit, it's great to know that 6' people can stand up straight in the middle. While I don't think I'll have any issues with the height, I plan to work the height factor in for a 6' person and that way when I sell it someday, I'll have a better shot.

I'm also planning to stay away from foam board and spray foam because they're flammable, and instead go with fiberglass insulation, even if the thinner areas will have a bit lower R value. The wooden bits will get Fire Tect sprayed all over them to protect them for a few years in case of a fire. That way while the inside might have a fire somewhere, it'll start relatively localized while the Elide fireball explodes to extinguish it (utility closet) or I spray my CO2 fire extinguisher at it (living areas).

My plans won't prevent all potential fire damage that could happen, but fiberglass insulation is one of the important safety measures I'm planning on since it's all over the shell of the house.

If anyone has ideas on how to beef up the R value of a thinner layer of fiberglass insulation, I'd appreciate it. (Thinsulate sprayed with Fire Tect perhaps?)

While I’m all in favor of being cognizant of fire hazards, I don’t think that should be you’re reasoning for going with fiberglass. Fiberglass is, as you alluded to, not nearly as efficient as foam (spray or board) per inch. Also, after inhaling more than I’d like to admit, it poses its own hazards like foam and damn near everything else in this crazy synthetic world we live in.

Your concern of fire hazards can be mitigated by proper wiring and fuse/breaker protection. Additionally, You’re likely already inside a giant tinderbox of plywood and lumber so the foam is far from being the only thing that could catch fire haha.

Do what works for you, but I think your fire concerns may cause you more pain than gain.

[musigenesis]

I second RamRod4's comments about fire. A lived-in skoolie is packed full of combustible materials as it is, so regardless of what insulation you use you'll either put a fire out as soon as it starts or the entire bus will be destroyed.

If anyone has ideas on how to beef up the R value of a thinner layer of fiberglass insulation, I'd appreciate it.

Just not going to happen. R-value is (literally) a function of a material's thermal conductivity and its thickness. The only way to increase the R-value of a thin layer of fiberglass is to replace it with some material other than fiberglass. Fiberglass is R-3.5 per inch, while XPS is R-5 per inch and polyiso is R-6.5 per inch (although this value declines at lower temperatures). Aerogel is about R-10 per inch but it's not exactly practical or cost-effective.

[HamSkoolie]

Not all foams, nor even types of foams, are equal. Check the fire rating. If the material has a 1 hour fire resistance rating, that's most likely better than your plain old wood. Also, if it can resist fire for 1hour, you're probably going to realize there is a fire and take corrective action. I can't imagine a smoke or CO detector not going off if the batteries haven't been pulled out.

[Gathman]

Just wanted to underscore that if you're careful, you can keep it comfortable for a 6' person. I've got 1" XPS, 1/2" plywood, and ~1/4" vinyl tile on the floor. We removed the sheet inner roof and used havelock wool insulation (amazing stuff, look into it before you choose fiberglass) , and ~1/4" composite floor tiles screwed directly into the ribs. I'm 6' and have a good inch when I'm in the center.

[john61ct]

If you aren't "following the 60's" but living off-grid in extreme weather conditions for weeks & months at a time

you will need to raise the roof for comfort and economy

unless all occupants are very short.

3-4" of polyiso is a good starting point.

More in the roof against Arctic cold, more in the floor if using aircon a lot.

[HamSkoolie]

Originally Posted by Gathman

Just wanted to underscore that if you're careful, you can keep it comfortable for a 6' person. I've got 1" XPS, 1/2" plywood, and ~1/4" vinyl tile on the floor. We removed the sheet inner roof and used havelock wool insulation (amazing stuff, look into it before you choose fiberglass) , and ~1/4" composite floor tiles screwed directly into the ribs. I'm 6' and have a good inch when I'm in the center.

Please do start a thread and tell us about these floor tiles. I'm having a hard time imagining a composite floor tile that would be rigid enough for this.

Also, what is the R value on the Havelock wool compared to closed cell spray foam that also seals out drafts and moisture (which aren't calculated when determining R value but do make a big impact in a drafty bus (not all are drafty but most are).

[HamSkoolie]

Originally Posted by john61ct

If you aren't "following the 60's" but living off-grid in extreme weather conditions for weeks & months at a time
you will need to raise the roof for comfort and economy
unless all occupants are very short.
3-4" of polyiso is a good starting point.
More in the roof against Arctic cold, more in the floor if using aircon a lot.

For someone concerned about interior height and not raising the roof 3-4" of any insulation isn't going to work.

[john61ct]

Originally Posted by HamSkoolie

For someone concerned about interior height and not raising the roof 3-4" of any insulation isn't going to work.

Yes exactly, that reinforces what I wrote.

Just like "good / fast / cheap, pick two"

[Veloc]

Originally Posted by ManWithNoBrows

Hi guys. Thanks for your input. I'm 5'6" so while I always figured I'd fit, it's great to know that 6' people can stand up straight in the middle. While I don't think I'll have any issues with the height, I plan to work the height factor in for a 6' person and that way when I sell it someday, I'll have a better shot.

I'm also planning to stay away from foam board and spray foam because they're flammable, and instead go with fiberglass insulation, even if the thinner areas will have a bit lower R value. The wooden bits will get Fire Tect sprayed all over them to protect them for a few years in case of a fire. That way while the inside might have a fire somewhere, it'll start relatively localized while the Elide fireball explodes to extinguish it (utility closet) or I spray my CO2 fire extinguisher at it (living areas).

My plans won't prevent all potential fire damage that could happen, but fiberglass insulation is one of the important safety measures I'm planning on since it's all over the shell of the house.

If anyone has ideas on how to beef up the R value of a thinner layer of fiberglass insulation, I'd appreciate it. (Thinsulate sprayed with Fire Tect perhaps?)

It it's a real concern for you, and you have the money, look at aerogel insulation. It'll cost you a lot of dollars per linear foot, but you can put a blowtorch on the bottom and your hand on top and not feel a thing. The R value is somewhere in the R30 range per inch of thickness for the pricey stuff, maybe more. They also have one designed for home use that is R9.6 per inch that would be ideal for buses, BUT as it is a blanket and not foam board you would need to support it so it doesn't crush.

[ManWithNoBrows]

I think what I failed to consider on insulation is how long it would take for insulation to start burning. If it takes 1 hour for XPS to catch fire before it goes whoosh, then I should be good. I mean, a burning hot wire will eventually fail in some way, but probably under an hour. (Load, fuse, wire breaks instead)

The load is more what I need to be concerned about. While I'm going with a Webasto heater and other webasto products, I do know that cheap Chinese heaters are built all wrong and I've seen one or more builds that went up in flames when they used those. I don't trust them, but it's an example of something that could burn the house down. So loads are more probable than fused appropriately sized wires, to cause a fire, IMO. I'll try to keep heavier loads quarantined from combustible materials, and heaters definitely won't touch them.

Thoughts?

[musigenesis]

I've never seen a build that has gone up in flames because of a diesel air heater.

[ManWithNoBrows]

Originally Posted by musigenesis

I've never seen a build that has gone up in flames because of a diesel air heater.

Maybe it was just the one then. I did see a different team take apart a Chinese heater and talked about the poor workmanship.

[HamSkoolie]

Originally Posted by ManWithNoBrows

Maybe it was just the one then. I did see a different team take apart a Chinese heater and talked about the poor workmanship.

While the Webastos are higher quality and if yo can afford them go for it, I would suggest that any fire started by one of the cheap Chinese versions was more likely installation or operation error than anything else.

They do use combustible (not flammable) fuel and create high heat. They also have fuel supply lines that can be compromised by improper installation and maintenance. So being a source of a fire is a possibility. But properly installed and maintained (remember, the skills and craftsmanship of skoolie and van builders is as variable as the words out of a politicians mouth) systems are safe and in use in thousands of rigs.

[RamRod4]

Originally Posted by HamSkoolie

While the Webastos are higher quality and if yo can afford them go for it, I would suggest that any fire started by one of the cheap Chinese versions was more likely installation or operation error than anything else.

They do use combustible (not flammable) fuel and create high heat. They also have fuel supply lines that can be compromised by improper installation and maintenance. So being a source of a fire is a possibility. But properly installed and maintained (remember, the skills and craftsmanship of skoolie and van builders is as variable as the words out of a politicians mouth) systems are safe and in use in thousands of rigs.

Very much agree.

This forum serves as a great resource to help people gain knowledge and bounce ideas off of each other. Generally, most of the builds on this forum are higher quality compared to what I’ve seen on Facebook/IG/Reddit. I’m not trying to offend anyone but there are a lot of people building skoolies that shouldn’t be allowed within arms reach of a vehicle and power tools. Those people are likely the root cause for the fires the OP may have heard about. Not that a freak accident can’t happen, but there probably 5 haphazard builds for every 1 quality build.