Reply
 
Thread Tools Display Modes
 
Old 05-05-2018, 08:16 PM   #1
Mini-Skoolie
 
BigBlue's Avatar
 
Join Date: Jul 2017
Posts: 46
Year: 1993
Coachwork: Thomas
Chassis: Saf-T-Liner
Engine: Cat 3116
Rated Cap: 78
Floor Options - 2X2's or just Insulate and Plywood?

Should the floor have 2X2's to prevent the insulation from being compressed? Afterall they say compressing insulation actually makes it less effective.

Or should you just lay insulation with glue then tongue and groove plywood?

Another reason I've heard to use 2X2's is to prevent the floor from warping/sagging under weight differential on each side of your build.


Opinions GO!

BigBlue is offline   Reply With Quote
Old 05-05-2018, 08:30 PM   #2
Traveling
 
Join Date: Dec 2017
Location: Dawsonville, Ga.
Posts: 8,955
Year: 1999
Coachwork: Genesis
Chassis: International
Engine: DT466/3060
Rated Cap: 77
Until someone proves me wrong with data, I think if you have plywood flooring over the rigid insulation you won't ever create enough pressure in any given area enough to compress the foam.
o1marc is offline   Reply With Quote
Old 05-05-2018, 09:53 PM   #3
Bus Geek
 
Join Date: Sep 2017
Location: Owasso, OK
Posts: 2,627
Year: 1999
Coachwork: Thomas
Chassis: Saf-T-Liner MVP ER
Engine: Cummins 6CTA8.3 Mechanical MD3060
Rated Cap: 46 Coach Seats, 40 foot
Quote:
Originally Posted by BigBlue View Post
Should the floor have 2X2's to prevent the insulation from being compressed? Afterall they say compressing insulation actually makes it less effective.

Or should you just lay insulation with glue then tongue and groove plywood?

Another reason I've heard to use 2X2's is to prevent the floor from warping/sagging under weight differential on each side of your build.


Opinions GO!

There are no good reasons to frame the floor, and doing so compromises the insulation.

Let's do the math ...

Compression strength of XPS Foam board ... 25 lbs/sq in

Rough area of shower wall base-plate ... 32x3.5" ... 112 sq in

The foam can support 112x25 = 2800 lbs ... or about 1.15 ton.

And that's ignoring completely the load spreading effect of the plywood sub-floor.

There is literally nothing you can put in the bus that will affect the foam underlayment.
__________________
Steve Bracken

Build Thread
Twigg is offline   Reply With Quote
Old 05-05-2018, 09:58 PM   #4
Traveling
 
Join Date: Dec 2017
Location: Dawsonville, Ga.
Posts: 8,955
Year: 1999
Coachwork: Genesis
Chassis: International
Engine: DT466/3060
Rated Cap: 77
Quote:
Originally Posted by Twigg View Post
There are no good reasons to frame the floor, and doing so compromises the insulation.

Let's do the math ...

Compression strength of XPS Foam board ... 25 lbs/sq in

Rough area of shower wall base-plate ... 32x3.5" ... 112 sq in

The foam can support 112x25 = 2800 lbs ... or about 1.15 ton.

And that's ignoring completely the load spreading effect of the plywood sub-floor.

There is literally nothing you can put in the bus that will affect the foam underlayment.
1.4 ton, but who's counting. I agree with you completely.
o1marc is offline   Reply With Quote
Old 05-05-2018, 10:50 PM   #5
Mini-Skoolie
 
BigBlue's Avatar
 
Join Date: Jul 2017
Posts: 46
Year: 1993
Coachwork: Thomas
Chassis: Saf-T-Liner
Engine: Cat 3116
Rated Cap: 78
Thank you for shedding some light on this!! I have no idea how building works and really didn't want to frame the floor anyhow
BigBlue is offline   Reply With Quote
Old 05-06-2018, 12:25 AM   #6
Mini-Skoolie
 
Join Date: Mar 2018
Location: Interior BC
Posts: 55
Year: 1998
Coachwork: Thomas
Chassis: Thomas
Engine: 8.3l Cummins
Ok, lovely calculations which don't mean much to me. I'm happy not to frame the floor, 1/2" ply over rigid board suits me to the ground. Any concerns about framing walls (probably 2"x2" studs) off this? What are you guys planning on doing for fixing?

Any Damp Proof Membrane (DPM)? Probably a whole new thread in itself, but I assume that everyone is making the metal skin whole again (coins/silicone seems easiest I've seen) so trapping moisture with a DPM beyond this is probably a recipe for rust...?
Curious Slug is offline   Reply With Quote
Old 05-06-2018, 03:20 PM   #7
Mini-Skoolie
 
BigBlue's Avatar
 
Join Date: Jul 2017
Posts: 46
Year: 1993
Coachwork: Thomas
Chassis: Saf-T-Liner
Engine: Cat 3116
Rated Cap: 78
I'd guess that the wall framing would be done by attaching wood to the walls of the bus and building off of that first? But I honestly haven't built yet and don't know a thing about it! XD

Or maybe framing specifically where you're building walls up so that you have a solid piece of wood under to attach to?
BigBlue is offline   Reply With Quote
Old 05-06-2018, 03:58 PM   #8
Mini-Skoolie
 
Join Date: Apr 2018
Posts: 20
Quote:
Originally Posted by Twigg View Post
There is literally nothing you can put in the bus that will affect the foam underlayment.
Dow and Owens Corning also do special foams for floor use. Down Highload 100 is rated for over seven tons per square foot.
Jshaul is offline   Reply With Quote
Old 05-08-2018, 09:07 AM   #9
Bus Geek
 
Brewerbob's Avatar
 
Join Date: Oct 2016
Location: Essex, MD
Posts: 3,680
Year: 1999
Coachwork: Blue Bird
Chassis: Blue Bird TC RE 3904, Flat Nose, 40', 277" wh base
Engine: 8.3L Cummins ISC 260hp, MT643, 4.44 rear
Rated Cap: 84 pax or 1 RV; 33,000lbs
Quote:
Originally Posted by Twigg View Post
There are no good reasons to frame the floor, and doing so compromises the insulation.

Let's do the math ...

Compression strength of XPS Foam board ... 25 lbs/sq in

Rough area of shower wall base-plate ... 32x3.5" ... 112 sq in

The foam can support 112x25 = 2800 lbs ... or about 1.15 ton.

And that's ignoring completely the load spreading effect of the plywood sub-floor.

There is literally nothing you can put in the bus that will affect the foam underlayment.
Nice use of numbers but here's a question for the non-framers, how do you calculate slope?

With rigid board you're pretty safe but I'm going to use spray foam so will use the 2x2s to keep things level.
Brewerbob is offline   Reply With Quote
Old 05-08-2018, 11:54 AM   #10
Bus Geek
 
Join Date: Sep 2017
Location: Owasso, OK
Posts: 2,627
Year: 1999
Coachwork: Thomas
Chassis: Saf-T-Liner MVP ER
Engine: Cummins 6CTA8.3 Mechanical MD3060
Rated Cap: 46 Coach Seats, 40 foot
Quote:
Originally Posted by Brewerbob View Post
Nice use of numbers but here's a question for the non-framers, how do you calculate slope?

With rigid board you're pretty safe but I'm going to use spray foam so will use the 2x2s to keep things level.
Few people ever get the bus completely level, so instead of using slope, measurements are taken from fixed reference points.

Once you get the floor flat, you and use a 90 degree from it to all the uprights.
__________________
Steve Bracken

Build Thread
Twigg is offline   Reply With Quote
Old 05-08-2018, 12:28 PM   #11
Bus Geek
 
Brewerbob's Avatar
 
Join Date: Oct 2016
Location: Essex, MD
Posts: 3,680
Year: 1999
Coachwork: Blue Bird
Chassis: Blue Bird TC RE 3904, Flat Nose, 40', 277" wh base
Engine: 8.3L Cummins ISC 260hp, MT643, 4.44 rear
Rated Cap: 84 pax or 1 RV; 33,000lbs
Quote:
Originally Posted by Twigg View Post
Few people ever get the bus completely level, so instead of using slope, measurements are taken from fixed reference points.

Once you get the floor flat, you and use a 90 degree from it to all the uprights.
Level isn't the right word as it is an RV and will be parked where ever and close enough is good enough.

Straight is a better term. I don't want it dipping here and there only to rise in the middle, sides, whatever. A marble going across the floor can be fixed with more air pressure on one side. A zigzag floor, not so much.

Speaking of leveling a bus, what are people using when parked? I know you can buy the RV leveling jacks but 1) does anyone bother 2) are they rated for a school bus? I guess rating wouldn't be a problem as even cranes have outriggers.
Brewerbob is offline   Reply With Quote
Old 05-08-2018, 05:54 PM   #12
Bus Geek
 
Join Date: Sep 2017
Location: Owasso, OK
Posts: 2,627
Year: 1999
Coachwork: Thomas
Chassis: Saf-T-Liner MVP ER
Engine: Cummins 6CTA8.3 Mechanical MD3060
Rated Cap: 46 Coach Seats, 40 foot
Quote:
Originally Posted by Brewerbob View Post

Speaking of leveling a bus, what are people using when parked? I know you can buy the RV leveling jacks but 1) does anyone bother 2) are they rated for a school bus? I guess rating wouldn't be a problem as even cranes have outriggers.
If you have the ability to fit them yourself, cost is a main issue.

You can fit RV-type self-leveling jacks, but I think the cost is around $3000 for the parts.

It can probably be done quite a bit cheaper, but I'm thinking that hydraulic jacks would be much easier to use than, for example, screw jacks that also exist.
__________________
Steve Bracken

Build Thread
Twigg is offline   Reply With Quote
Old 05-09-2018, 08:47 AM   #13
Bus Geek
 
Brewerbob's Avatar
 
Join Date: Oct 2016
Location: Essex, MD
Posts: 3,680
Year: 1999
Coachwork: Blue Bird
Chassis: Blue Bird TC RE 3904, Flat Nose, 40', 277" wh base
Engine: 8.3L Cummins ISC 260hp, MT643, 4.44 rear
Rated Cap: 84 pax or 1 RV; 33,000lbs
Quote:
Originally Posted by Twigg View Post
If you have the ability to fit them yourself, cost is a main issue.

You can fit RV-type self-leveling jacks, but I think the cost is around $3000 for the parts.

It can probably be done quite a bit cheaper, but I'm thinking that hydraulic jacks would be much easier to use than, for example, screw jacks that also exist.
Truff. Skoolie people are crafty (and cheap). 4 Horrible Freight bottle jacks at 6 tons each would be MUCH cheaper than teh gold plated RV stuff.
Brewerbob is offline   Reply With Quote
Old 05-09-2018, 09:58 AM   #14
Bus Nut
 
Yukon Cornelius's Avatar
 
Join Date: Apr 2018
Location: Barrie ON
Posts: 440
Year: 1997
Coachwork: Thomas
Chassis: International
Engine: T444E
Rated Cap: 72
Quote:
Originally Posted by Twigg View Post
There are no good reasons to frame the floor, and doing so compromises the insulation.

Let's do the math ...

Compression strength of XPS Foam board ... 25 lbs/sq in

Rough area of shower wall base-plate ... 32x3.5" ... 112 sq in

The foam can support 112x25 = 2800 lbs ... or about 1.15 ton.

And that's ignoring completely the load spreading effect of the plywood sub-floor.

There is literally nothing you can put in the bus that will affect the foam underlayment.
What about base anchoring your, walls, seating, cabinets etc? are you drilling through the floor and using standoff bolts? or only relying on the wall/roof anchor points? or putting a floor strap in for those key locations?

Would be really shitty to god forbid you get into an accident that was survivable until the lower cabinets full of likely most of your heavy items came off the wall and to the front of the bus during the rapid deceleration. I ponder this as I've seen this happen in both aviation and vehicular incidents.

my background in aviation incidents may have me being over cautious?

Yukon
Yukon Cornelius is offline   Reply With Quote
Old 05-09-2018, 10:07 AM   #15
Mini-Skoolie
 
Join Date: Apr 2018
Location: Revelstoke, BC, Canada
Posts: 65
Year: 1995
Coachwork: Blue Bird
Engine: Cummins 8.3l 12v
Rated Cap: 84 pax
Quote:
Originally Posted by Curious Slug View Post
Ok, lovely calculations which don't mean much to me. I'm happy not to frame the floor, 1/2" ply over rigid board suits me to the ground. Any concerns about framing walls (probably 2"x2" studs) off this? What are you guys planning on doing for fixing?
1/2" will be fine depending on what you're putting over it. If the floor finish has some rigidity and will span joints in the ply then you don't have to worry about the edges (which are vulnerable to point loads and could dip). If you're using a thin sheet finish like vinyl then I'd use a T&G ply.

No concerns with 2x2 if you're sheeting it with a wood product that will reinforce the connections in the 2x2 (it's a bit small section for good mechanically fastened joints on it's own, though you can always add a dab of PL that will help). 2x4 for partitions is complete overkill on a bus except at corners where you need the section size to make internal corner fixing for the finish - create an L in plan with a 2x4 and a 2x2.

Glue the bottom plate to the ply with a polyurethane adhesive (LePage PL or similar) and secure with screws just long enough penetrate the thickness of the ply to hold in place and down while the glue sets

Quote:
Originally Posted by Curious Slug View Post
Any Damp Proof Membrane (DPM)? Probably a whole new thread in itself, but I assume that everyone is making the metal skin whole again (coins/silicone seems easiest I've seen) so trapping moisture with a DPM beyond this is probably a recipe for rust...?
DPM (damp proof membrane) is a water-impermeable layer that prevents ground moisture from rising into a structure so not exactly applicable in this scenario but I think I see what you're getting at. Your floor should be sealed against moisture ingress but rigid XPS (the coloured Extruded Polystyrene) is water resistant enough that any moisture entering the body wouldn't affect the floor. EPS - the 'white-balls' Expanded Polystyrene is more water absorbent but still only 3% so prob ok, but it has a lower insulation value, is less rigid, is messier to work with, is more damaging in manufacture, etc, etc - it's cheaper, and considerably, but that is it's only benefit.

Glue the foam down then glue the ply to the foam - Use a product like LePage PL300, designed for adhering foam with damaging it. XPS is vapour impermeable so creates a vapour barrier but I'd tape or spray foam the seams (depending on how tight you get them), and the perimeter of, the foam to prevent any chance of water vapour reaching the cold floor under and condensing.
N'om'ad is offline   Reply With Quote
Old 05-09-2018, 11:28 AM   #16
Bus Nut
 
Join Date: Dec 2017
Posts: 453
Coachwork: Gillig
Quote:
Originally Posted by Brewerbob View Post
Truff. Skoolie people are crafty (and cheap). 4 Horrible Freight bottle jacks at 6 tons each would be MUCH cheaper than teh gold plated RV stuff.
Funny you mention HF. I was thinking about picking up a few of these 20ton Air Hydraulic Bottle Jacks. I figured I could even run them off the bus air once I get that set up?
ComfortEagle is offline   Reply With Quote
Old 05-09-2018, 12:20 PM   #17
Bus Geek
 
Join Date: Sep 2017
Location: Owasso, OK
Posts: 2,627
Year: 1999
Coachwork: Thomas
Chassis: Saf-T-Liner MVP ER
Engine: Cummins 6CTA8.3 Mechanical MD3060
Rated Cap: 46 Coach Seats, 40 foot
Quote:
Originally Posted by ComfortEagle View Post
Funny you mention HF. I was thinking about picking up a few of these 20ton Air Hydraulic Bottle Jacks. I figured I could even run them off the bus air once I get that set up?
Four of those would make a great leveling system.

It would be ideal if they work upside down, but I suspect they won't. It would be worth checking.
__________________
Steve Bracken

Build Thread
Twigg is offline   Reply With Quote
Old 05-10-2018, 11:01 AM   #18
Bus Geek
 
Brewerbob's Avatar
 
Join Date: Oct 2016
Location: Essex, MD
Posts: 3,680
Year: 1999
Coachwork: Blue Bird
Chassis: Blue Bird TC RE 3904, Flat Nose, 40', 277" wh base
Engine: 8.3L Cummins ISC 260hp, MT643, 4.44 rear
Rated Cap: 84 pax or 1 RV; 33,000lbs
Quote:
Originally Posted by Twigg View Post
It would be ideal if they work upside down, but I suspect they won't. It would be worth checking.
Hmm, a normal bottle jack should? I'm assuming it's filled and doesn't have an air pocket in the design. No clue about air over hydraulic. Definitely worth checking.

The 12 ton is $30 cheaper and as you're getting 4 of them... more than enough to completely lift the bus if you were so inclined. Hell, one would lift mine fully loaded.
Brewerbob is offline   Reply With Quote
Old 05-10-2018, 11:06 AM   #19
Bus Geek
 
Brewerbob's Avatar
 
Join Date: Oct 2016
Location: Essex, MD
Posts: 3,680
Year: 1999
Coachwork: Blue Bird
Chassis: Blue Bird TC RE 3904, Flat Nose, 40', 277" wh base
Engine: 8.3L Cummins ISC 260hp, MT643, 4.44 rear
Rated Cap: 84 pax or 1 RV; 33,000lbs
Kinda on the same (off)topic, has anyone added a winch to their bus. I think it was Somewhere that got his bus stuck in the sand with a flat. I got someone or other's magazine that had winches up to 17,500 lbs for $700 ish. Better than a $2,000 tow if you take the wrong road.

The rule of thumb as I understand it is 3x GVR to get unstuck from the mud but 1) that's mud (which has suction) and 2) is buried to the frame. 17,500 should be plenty for a little wheel spin here or there.
Brewerbob is offline   Reply With Quote
Old 05-10-2018, 11:09 AM   #20
Bus Geek
 
Brewerbob's Avatar
 
Join Date: Oct 2016
Location: Essex, MD
Posts: 3,680
Year: 1999
Coachwork: Blue Bird
Chassis: Blue Bird TC RE 3904, Flat Nose, 40', 277" wh base
Engine: 8.3L Cummins ISC 260hp, MT643, 4.44 rear
Rated Cap: 84 pax or 1 RV; 33,000lbs
P.S. HF has those too.
https://www.harborfreight.com/18000-...ake-62194.html

P.S.S. I did find 60,000 lb military winches for between $5k and $10k the other day for those that do want to take their buses mudding.
Brewerbob is offline   Reply With Quote
Reply

Tags
build, floor, flooring, insulation, plywood

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


» Featured Campgrounds

Reviews provided by

Powered by vBadvanced CMPS v3.2.3

All times are GMT -5. The time now is 09:37 AM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2020, vBulletin Solutions, Inc.
×