Do all school buses have a plywood subfloor

[Unpluggedone]

Advantages it’s got some give to keep the kids from breaking their skulls when they land on it. It’s not 3/4” thick more like 1/4 or 3/16 and it does insulate a lot compared to having the steel floor directly under the vinyl or carpet. Plywood is extremely durable lasting for decades and decades unlike other substances

Disadvantage is after 40-50 years it will disintegrate if subject to too much moisture

 

[Doktari]

I have no idea how many buses have plywood floor. Mine does. I like marine plywood if I can keep it dry and reduce rusting. Where are school buses prone to leaking from? Do the passenger windows leak?. Ive been wondering if they are removed from the inside? Do the windows push in when removing? I think my Washington state bus floor has a little normal rust but will last the rest of the life of the bus. As long as I can stop the water. So I’m going to cover all the side windows with aluminum and reseal the roof. If that doesn’t do it I’ll go under the bus and see if water is infiltrating from underneath. Thanks and good luck with your floor.

 

[EastCoastCB]

Advantages it’s got some give to keep the kids from breaking their skulls when they land on it. It’s not 3/4” thick more like 1/4 or 3/16 and it does insulate a lot compared to having the steel floor directly under the vinyl or carpet. Plywood is extremely durable lasting for decades and decades unlike other substances

Disadvantage is after 40-50 years it will disintegrate if subject to too much moisture

The plywood bus floor I just pulled up was very much thicker than that. It was at least 5/8 or 3/4.
It didn't last decades, either. It was rotten and hid tons of rust on an otherwise rust free texas bus.

 

[o1marc]

The plywood bus floor I just pulled up was very much thicker than that. It was at least 5/8 or 3/4.
It didn't last decades, either. It was rotten and hid tons of rust on an otherwise rust free texas bus.

I've never seen plywood floors as thin as 1/4-3/8", it's always been 3/4".

 

[alpinekid]

mine has thick plywood, from what I can see in the old bolt holes, it might be 3/4 and its in good shape. When I look at the bare spots left by the backup washers on the under side it looks like a thin galvanize metal floor, then thick plywood and then hard rubber sheet for the top surface.
I've seem no sign of rust so I'm not touching it. I just have to plug up all the holes that I'm not using.

 

[brokedown-SKO]

I recently made a video about how I pulled up my very stubborn rubber+wood floor. Might be helpful for you.

 

[o1marc]

mine has thick plywood, from what I can see in the old bolt holes, it might be 3/4 and its in good shape. When I look at the bare spots left by the backup washers on the under side it looks like a thin galvanize metal floor, then thick plywood and then hard rubber sheet for the top surface.
I've seem no sign of rust so I'm not touching it. I just have to plug up all the holes that I'm not using.

Major rust could be hidden under good looking ply. It would be a shame at this point to not go ahead and endure you have a solid base to start. Where is the bus from? How are you going to leak proof all the seat bolt holes?

 

[Native-SKO]

Major rust could be hidden under good looking ply. It would be a shame at this point to not go ahead and endure you have a solid base to start. Where is the bus from? How are you going to leak proof all the seat bolt holes?

Ditto.


Our floor showed no signs of hiding anything. However, once the wood flooring was removed, I could see through to the ground aroubd the wheel wells.

 

[banman]

Hmmm, I'm beginning to think (as I read more and more on this forum) one is really lifting the plywood to check the condition of the plywood, or replace the plywood. The very thin sheet metal below the plywood is just there to protect the plywood from the elements and mechanical fluids. The 16ga or 18ga sheet has very little strength compared to the 3/4" plywood...

I'm guessing a bus with no plywood uses a thicker ga (gauge) sheet metal with the rubber tread covering.

Thoughts...?

 

[EastCoastCB]

Hmmm, I'm beginning to think (as I read more and more on this forum) one is really lifting the plywood to check the condition of the plywood, or replace the plywood. The very thin sheet metal below the plywood is just there to protect the plywood from the elements and mechanical fluids. The 16ga or 18ga sheet has very little strength compared to the 3/4" plywood...

I'm guessing a bus with no plywood uses a thicker ga (gauge) sheet metal with the rubber tread covering.

Thoughts...?

NO they're the same thickness. Its 14ga I'm pretty sure. The plywood isn't structural. Not at all.

 

[Native-SKO]

NO they're the same thickness. Its 14ga I'm pretty sure. The plywood isn't structural. Not at all.

I concur. The back 2/3 of our bus has no subfloor, only bare metal. It is very sturdy. We'll be using it as an interstate moving van here in a couple of days. We have already done so for our grandson's move across town. The floor is quite robust.

 

[EastCoastCB]

If the plywood were anything structural they'd put it on every bus built.
They have to pass the same standards whether or not there's plywood.

 

[musigenesis]

Hmmm, I'm beginning to think (as I read more and more on this forum) one is really lifting the plywood to check the condition of the plywood, or replace the plywood. The very thin sheet metal below the plywood is just there to protect the plywood from the elements and mechanical fluids. The 16ga or 18ga sheet has very little strength compared to the 3/4" plywood...

I'm guessing a bus with no plywood uses a thicker ga (gauge) sheet metal with the rubber tread covering.

Thoughts...?

The 16ga sheet metal (that's the thickness on my bus, at least) has the edges of the floor panels bent into c-channels and welded together (to create effectively an I-beam) and additional hat channel stiffeners are spot-welded to the underside. So the whole floor structure is much stiffer and stronger than simple flat sheet metal would be.

 

[banman]

I concur. The back 2/3 of our bus has no subfloor, only bare metal. It is very sturdy. We'll be using it as an interstate moving van here in a couple of days. We have already done so for our grandson's move across town. The floor is quite robust.

If the plywood were anything structural they'd put it on every bus built.
They have to pass the same standards whether or not there's plywood.

The 16ga sheet metal (that's the thickness on my bus, at least) has the edges of the floor panels bent into c-channels and welded together (to create effectively an I-beam) and additional hat channel stiffeners are spot-welded to the underside. So the whole floor structure is much stiffer and stronger than simple flat sheet metal would be.

That's why I ask... Thanks!

But Musicgensis address' my point -- 16ga sheet metal has little strength -- it's the compound bends that give it structure -- if you fastened 3/4" plywood to the sub-floor structure as securely as the sheet metal is fastened to the sub-frame it would be stronger than the sheet metal -- it would also take an incredible amount of labor to build that way -- compared to spot welding which is super fast, cheap, strong (till it rusts...)

14ga is the usual thickness of a shovel blade -- I'd be surprised if any floors sheet metal was that thick.

 

[EastCoastCB]

That's why I ask... Thanks!

But Musicgensis address' my point -- 16ga sheet metal has little strength -- it's the compound bends that give it structure -- if you fastened 3/4" plywood to the sub-floor structure as securely as the sheet metal is fastened to the sub-frame it would be stronger than the sheet metal -- it would also take an incredible amount of labor to build that way -- compared to spot welding which is super fast, cheap, strong (till it rusts...)

14ga is the usual thickness of a shovel blade -- I'd be surprised if any floors sheet metal was that thick.

Your'e right- 16ga.

16ga is incredibly thick for what it is. I've cut and handled plenty of it.
All the floors are designed to do is keep kids from falling through to the road lol.

 

[musigenesis]

All the floors are designed to do is keep kids from falling through to the road lol.

They're too good at that, IMHO. Need to get some value engineers on it - if you let the heavier kids fall through, you'll save on cafeteria costs.

 

[o1marc]

Hmmm, I'm beginning to think (as I read more and more on this forum) one is really lifting the plywood to check the condition of the plywood, or replace the plywood. The very thin sheet metal below the plywood is just there to protect the plywood from the elements and mechanical fluids. The 16ga or 18ga sheet has very little strength compared to the 3/4" plywood...

I'm guessing a bus with no plywood uses a thicker ga (gauge) sheet metal with the rubber tread covering.

Thoughts...?

No, the main reason for lifting the plywood is to address the rusty floor. Chances are good the ply will be useless after removing.

 

[Brad_SwiftFur]

All the floors are designed to do is keep kids from falling through to the road lol.

I'd disagree with that, the floor is engineered for much more than that. The frame does not extend the width of the vehicle and the floor and its related joists must support the walls and roof. It also serves as part of the overall structure if the bus rolls or is struck from the side - most smaller vehicles are going to hit the floor (the side skirts will have some impact protection, but guess what? They're attached to the floor too.)

 

[banman]

I'd disagree with that, the floor is engineered for much more than that. The frame does not extend the width of the vehicle and the floor and its related joists must support the walls and roof. It also serves as part of the overall structure if the bus rolls or is struck from the side - most smaller vehicles are going to hit the floor (the side skirts will have some impact protection, but guess what? They're attached to the floor too.)

Exactly -- The 3/4" ply if properly secured to the sub-frame will add way more (math term!) strength than a sheet of 16ga.

I will accept that the ply isn't needed to meet "school bus safety code" but that doesn't mean it still wouldn't build a stronger floor.

 

[EastCoastCB]

Exactly -- The 3/4" ply if properly secured to the sub-frame will add way more (math term!) strength than a sheet of 16ga.

I will accept that the ply isn't needed to meet "school bus safety code" but that doesn't mean it still wouldn't build a stronger floor.

The sheet of steel gets its strength from the shape its made into.

The plywood is an add on and isn't required for the federal crash testing as it isn't an integral part of the bus. If it were every state would be required to buy the plywood add on.