Framing floor

[CC08]

I’ve seen a lot of pros and cons to framing the bus floor. Lately I’ve been seeing people gluing insulation down and then plywood right on top of it. We are trying to save inches as we aren’t doing a roof raise. Tell me if you framed the floor or skipped it! I’m wondering what you bolted your furniture to, if you did skip the framing.

 

[o1marc]

I laid one layer of polyiso 1/2" and one layer of 1" rigid pink. Cut tight to prevent movement. I laid the vapor barrier and snap together laminate flooring floating on top. Fixtures will be attached to wall ribs.

 

[musigenesis]

I’ve seen a lot of pros and cons to framing the bus floor. Lately I’ve been seeing people gluing insulation down and then plywood right on top of it. We are trying to save inches as we aren’t doing a roof raise. Tell me if you framed the floor or skipped it! I’m wondering what you bolted your furniture to, if you did skip the framing.

Doing a free-floating floor or doing "joists" (essentially wooden furring strips on the floor with cut strips of foam in between) won't really affect the height of your floor, which is determined by the height of the insulation + the height of your flooring (plywood + vinyl sheeting, for example) in both cases. Except insofar as wood is not as good an insulator as foam (about R1 per inch vs. R4), so the more of your layer underneath the plywood is composed of the wood furring strips instead of foam, the less good its insulation factor will be (this is pretty minor though).

Not all foams have the same resistance to compression, however, so they're theoretically not all suitable for a floating floor (although I've seen all of them used in this way).

 

[Shawn & Ash]

We are thinking about thin insulation for the floors also to save head space. Then a thin sheet of pvc over it as our floor base. It’s sturdy and less flammable lol. Would this work and do we need to frame the floor or can we screw into the structure? I would think definitely frame it but trying to save where we can.

 

[rembus]

Thoughts on bolting 2x4s to the floor to have a strong base for furniture or other modifications down the road? Also thinking about using some screws to make sure the metal floor is pulled up to meet the wood everywhere.

Pros? Cons? Anything helps

 

[frugalfannie]

Thoughts on bolting 2x4s to the floor to have a strong base for furniture or other modifications down the road? Also thinking about using some screws to make sure the metal floor is pulled up to meet the wood everywhere.

Pros? Cons? Anything helps

We framed the floor with 2x4s and didn't bolt or screw it to anything. We used pressure against the walls to hold it in place basically, left to right and front to back. Of course, all the 2x4s are screwed to each other but they are not screwed into the walls or floor.

 

[musigenesis]

Thoughts on bolting 2x4s to the floor to have a strong base for furniture or other modifications down the road? Also thinking about using some screws to make sure the metal floor is pulled up to meet the wood everywhere.

Pros? Cons? Anything helps

For my floor, I welded wood screws upright on the steel floor, then screwed 2" pieces of dowel (1.25" diameter) through holes in the 2" XPS foam board and onto these screws; I then screwed 3/4" plywood to the dowels on top. This gives my plywood flooring a solid mechanical connection to the steel floor and lets me secure furniture and cabinetry to it with no problem, and without putting any new holes in the steel floor.

This basically evolved out of my original plan to do something like what you're suggesting, with 2X "joists" bolted to the steel floor. I went from there to welding angle brackets on the floor that I could screw the 2X4s to sideways, then to welding just the screws and spinning down small blocks onto them. This would have involved cutting lots of very accurate small square holes in the foam board to fit down onto them, and I eventually realized that dowel could be spun down after the holes were cut so no elaborate measuring would be required (the spots for each hole can be marked by just pressing the foam board down over the welded screws).

 

[rembus]

For my floor, I welded wood screws upright on the steel floor, then screwed 2" pieces of dowel (1.25" diameter) through holes in the 2" XPS foam board and onto these screws; I then screwed 3/4" plywood to the dowels on top. This gives my plywood flooring a solid mechanical connection to the steel floor and lets me secure furniture and cabinetry to it with no problem, and without putting any new holes in the steel floor.

This basically evolved out of my original plan to do something like what you're suggesting, with 2X "joists" bolted to the steel floor. I went from there to welding angle brackets on the floor that I could screw the 2X4s to sideways, then to welding just the screws and spinning down small blocks onto them. This would have involved cutting lots of very accurate small square holes in the foam board to fit down onto them, and I eventually realized that dowel could be spun down after the holes were cut so no elaborate measuring would be required (the spots for each hole can be marked by just pressing the foam board down over the welded screws).

That sounds like an awesome solution! I wish I had a welder and welding experience! If I seal my bolt holes with auto sealant before tightening, do you think that would suffice for keeping water from entering the holes I've created?

Cheers!

 

[musigenesis]

That sounds like an awesome solution! I wish I had a welder and welding experience! If I seal my bolt holes with auto sealant before tightening, do you think that would suffice for keeping water from entering the holes I've created?

Cheers!

Yeah, you'll be fine. I don't think screws poking through the floor to the underside are actually a problem at all, even without sealant. I think the exposed tips rust and then the screws expand (from the rust) and essentially seal the openings from further water incursion. My bus was about the biggest rust catastrophe you'll see, and it had numerous screws sticking through the floor that were fine and not a source of water incursion.

I like having a flooring system that doesn't introduce new holes because I just don't like holes. Welding machines can be had pretty cheap and welding screws to a floor is one of the simpler things you can do with one. The biggest problem is not stepping on them.

 

[rembus]

We framed the floor with 2x4s and didn't bolt or screw it to anything. We used pressure against the walls to hold it in place basically, left to right and front to back. Of course, all the 2x4s are screwed to each other but they are not screwed into the walls or floor.

That sounds really interesting. Any issues with expansion/contraction from hot/cold weather causing those friction fits to your walls to loosen or over tighten? How has it held up for you since building? Have you found while driving that the floor bounces around at all?

If it holds up, I'd be really interested as that would be super easy to install!!

Cheers!

 

[frugalfannie]

That sounds really interesting. Any issues with expansion/contraction from hot/cold weather causing those friction fits to your walls to loosen or over tighten? How has it held up for you since building? Have you found while driving that the floor bounces around at all?

If it holds up, I'd be really interested as that would be super easy to install!!

Cheers!

The floor is framed. we have not yet insulated and covered it. We will use closed cell spray foam so I think we will be fine with regards to expansion and contraction. Ours will be built for full time living with a mini split for cooling and diesel heaters for winter. we should be able to maintain a pretty good climate inside. I have seen Life is a Joy and Zeppelin Travels use similar system and they have been at it a few years each. Once the build is complete with kitchen and such I doubt the floor will be able to bounce at all. LOL

 

[WillytheMule]

Our bus has what appears to be a coat (of various thicknesses) of spray foam covered by what I think is undercoat on the bottom of the vehicle. Has anyone encountered this? I had to dig into the foam and whatnot to get the nuts on the seat bolts. The metal looks fantastic under it all. Do you think I can just reapply some foam and undercoating, once I'm done with demo and call it good? Is this a viable layer of insulation? I mean after I figure out any plumbing or wiring that may need to be ran. Maybe I should I REALLY apply some foam down there with a good coat of undercoat. Would I be able to skip the framing of the floor and just lay the subflooring to the metal floor? Thoughts?

Sorry about the grammar. Sausage fingers and phone typing do not mix.