No metal floor!

[Champagne]

Finally got around to pulling up the plywood in my shuttle bus and as it turns out there are large sections with no metal flooring. In other words, underneath the plywood, are the coolant lines etc. and the ground. This sort of throws a wrench in my plan of insulating underneath the plywood. Any suggestions for how to move forward?

I'll post pictures soon when I head out to the bus next time.

Thanks!

[Piper]

I came across this same problem in my shuttle bus. The best solution we came up with after asking around was to install 3/4 inch marine grade plywood, treat it, and then coat on a layer of roofing tar facing the ground to protect the wood from road debris. Then we framed and insulated on top of that and plan on adding a 1/2 inch final layer of plywood on top. Although marine grade plywood is more expensive, it handles water way better and is good to have as an extra safety measure considering there’s no metal floor. Hope this helps, I sure needed it when I was lost!

[BeNimble]

The last thing you should do is seal the bottom of the wood, it will just hold in water and rot the wood.
Marine plywood is also just extra expense for nothing of value. Marine plywood does not have voids in the plys (where the knots were) which makes it stronger for the same weight over regular plywood. I suppose you could use 5/8 instead of 3/4 for 2x the cost to get 1/8 more head clearance, otherwise wasted money you could spend on insulation.

One could weld in some steel so it could rust, like the other buses.

Just put the wood back in and insulate on top of it to solve this 'problem'.

[s2mikon]

My old Gillig has a plywood floor and is 50+ years old and is in real good shape. The factory undercoated it with a bitumen based product and then sprayed silver paint on top of that. I have cut a few holes in it with a hole saw and I wish I could buy that kind of quality plywood today. What did the your body manufacture use to seal it if at all?

[Danjo]

There are definitely different grades of plywood. The term “marine grade” is used by products that might not measure up to others that call themselves the same. It’s important to understand the types of glue used in the manufacture of plywood and also understand the number of plys have an effect on the rigidity of the product.

There are pros and cons to sealing the underside, but I think that if you can imagine the soaking that the underside will get after days of driving on wet roads, that you would probably agree that applying a sealing layer is a good idea.

Here’s a link to an explanation of glues used in plywood

http://theplywood.com/glues

[Piper]

Thanks for making me feel better about my choices Danjo hahah

[Champagne]

Thanks for the responses guys!

I am not sure exactly what type of plywood or sealant was used on the original body. It is a 2006 build from El Dorado. Unfortunately, I haven't been able to find a description of their builds online that matches mine, but I will try to get in touch with them.

Fortunately, The plywood and all of the metal support seems to be in really good condition, and the bus has been in Washington State the whole time where we get plenty of rain.

I suppose my next move is to figure out the insulation on top of the plywood as BeNimble suggests. My question then is what type of insulation? (I know this is a highly debated topic), and do I then lay more plywood on top of the insulation? I am trying to save headroom since I'm 6'2", but also don't want to cause issues walking on the insulation (maybe there's no need to worry about that?). My original plan was to use Rmax sheets, but I am not sure how those would fare walking directly on them.

Please forgive my ignorant questions as this is my first bus build.

[Champagne]

Originally Posted by Danjo

There are definitely different grades of plywood. The term “marine grade” is used by products that might not measure up to others that call themselves the same. It’s important to understand the types of glue used in the manufacture of plywood and also understand the number of plys have an effect on the rigidity of the product.

There are pros and cons to sealing the underside, but I think that if you can imagine the soaking that the underside will get after days of driving on wet roads, that you would probably agree that applying a sealing layer is a good idea.

Here’s a link to an explanation of glues used in plywood

http://theplywood.com/glues

Thanks for this link! I am sure it will come in handy.

[musigenesis]

To save headroom, you could glue together a sort of sandwich with 3/4" plywood on top, then 2" XPS foam board (or whatever thickness you're using) and 1/4" plywood on the bottom (or even sheet metal on the bottom - the rebuilt part of my floor is essentially like your bus with just open beams, and I covered these openings with 14 ga. sheet metal then XPS on top of that and then plywood on top of the sheet metal), and then set this onto your frame. This should be even stiffer than just 3/4" plywood (which is plenty stiff already).

XPS foam board is rated for 20-25 PSI which is strong enough if it's under a stiff top layer of plywood but isn't enough to be walking around on it. A 100-pound ballerina en pointe would easily dent it - or just kneeling on it will leave knee prints as my flooring testifies.

[BeNimble]

What is your finish flooring? Hardwood, Tile, Laminate all are plenty strong on top of foam board. Sheet vinyl would need maybe something, but maybe not if thick stuff, the cheapy thin stuff, well don't use that anyway. You can test it yourself, don't believe free advice on the internet.

[Danjo]

Originally Posted by musigenesis

To save headroom, you could glue together a sort of sandwich with 3/4" plywood on top, then 2" XPS foam board (or whatever thickness you're using) and 1/4" plywood on the bottom (or even sheet metal on the bottom - the rebuilt part of my floor is essentially like your bus with just open beams, and I covered these openings with 14 ga. sheet metal then XPS on top of that and then plywood on top of the sheet metal), and then set this onto your frame. This should be even stiffer than just 3/4" plywood (which is plenty stiff already).

XPS foam board is rated for 20-25 PSI which is strong enough if it's under a stiff top layer of plywood but isn't enough to be walking around on it. A 100-pound ballerina en pointe would easily dent it - or just kneeling on it will leave knee prints as my flooring testifies.

SIP panel totally came to my mind

[RamRod4]

Advantech.

3/4" Advantech subfloor and never worry about it again. Find it at you local lowes or HD

[Brian S]

I had the same issue. On my bus I sheeted the floor with 18 Ga galvanized attached with sheet metal screws and calk. Overlaid with 1" thick insulation and 3/4" plywood over that.

[Mekanic]

If your going to have wood as your primary flooring use ADVANTECH sheeting

Its as close to waterproof flooring as you can get. (If i remember right it has a 50 year water damage warranty)
https://www.huberwood.com/advantech/subflooring

[Champagne]

Originally Posted by Brian S

I had the same issue. On my bus I sheeted the floor with 18 Ga galvanized attached with sheet metal screws and calk. Overlaid with 1" thick insulation and 3/4" plywood over that.

Thanks Brian!,

So you laid the metal sheeting down where the original plywood was and then insulation and then plywood back down on top of that? or was all of this built on top of the existing plywood?

[Champagne]

Here are some photos of the flooring as promised. Thanks everyone for the tips. I checked out the Avantech subflooring and this seems like a good option. I am still a little hesitant to take out the existing plywood though because it is in such good condition both on top and underneath. If I were to keep the original plywood, sounds like the best option is to do a thin insulation layer and then another thinner plywood layer on top of that. I'm a little considered about my headroom at that point, but I think I can get some off the ceiling.

[musigenesis]

Originally Posted by Champagne

Here are some photos of the flooring as promised. Thanks everyone for the tips. I checked out the Avantech subflooring and this seems like a good option. I am still a little hesitant to take out the existing plywood though because it is in such good condition both on top and underneath. If I were to keep the original plywood, sounds like the best option is to do a thin insulation layer and then another thinner plywood layer on top of that. I'm a little considered about my headroom at that point, but I think I can get some off the ceiling.

Leave the plywood ... take the cannoli.

[roach711]

Our 2000 Aerotech has the same plywood floor and it has been a solid sub floor for our build. I used 3/4" poly-iso foam boards with 3/4" flake board covering it and linoleum for the final floor. I used wood cleats to support the flake board but many here have skipped that step and had no problems with the insulation board crushing under the weight of people and cabinets. .

I'm 6'1" tall and still have plenty of head room with another 3/4" poly-iso foam panel glued to the ceiling.


Eldorado is very good about answering questions regarding a specific bus. I emailed my VIN and got detailed wiring schematics.

[Champagne]

[/QUOTE]

Originally Posted by roach711

Our 2000 Aerotech has the same plywood floor and it has been a solid sub floor for our build. I used 3/4" poly-iso foam boards with 3/4" flake board covering it and linoleum for the final floor. I used wood cleats to support the flake board but many here have skipped that step and had no problems with the insulation board crushing under the weight of people and cabinets. .

I'm 6'1" tall and still have plenty of head room with another 3/4" poly-iso foam panel glued to the ceiling.


Eldorado is very good about answering questions regarding a specific bus. I emailed my VIN and got detailed wiring schematics.

Awesome! This is probably what I will end up doing as well. Thanks man! Did your ceiling also have this kind of corrugated material sandwiched between fiberglass?

[Champagne]

This is what my ceiling looks like. There were these plastic inserts I removed, which gave a good view of the construction.