Floor insulation

[Jcparmley]

I was wondering what you think about this plan for my floor.  I am doing a roof raise so I won't lose headroom when I insulate the floor.  I am planing on tearing out the old floor and clean all of the gunk under the original floor.  I will weld in tubing in the ceiling of the bay so their won't be any clear span of over 24 inch and the new floor will be well supported.  I plan on using 1/4 marine ply then 3.5 inch closed cell foam board then 1/2 inch tongue and groove underpayment and vinyl plank flooring.   My hope is the floor will be solid without having to run a bunch of furring strips in the floor.  THe compression rating on the foam is very high.  What are your thoughts?

[Dave5Cs]

Remember to leave accesses to the engine compartment able to be opened after your done and if you can make them larger is really nice. Some put beds or closets over them and then have to tear out everything to get to the back of the engine.
Otherwise it sounds feasible. We used 5/8" silent floor tongue and groove.

[Gary Hatt - Publisher BCM]

You should consider using EHP for your insulation, especially in the floor because it is very thin but very efficient.  Check them out. http://www.engineheatprotection.com/

[Jim Blackwood]

Is that stuff still ungodly expensive, or have the prices begun to come down?

[Gary Hatt - Publisher BCM]

Is that stuff still ungodly expensive, or have the prices begun to come down?

Well, you get what you pay for. I have not looked at their prices lately but I have heard from several people that it is worth every penny.  What it costs will be saved over the years in heating and cooling your bus.  You can read about it in the September 2018 issue of BCM by clicking here...  https://www.busconversionmagazine.com/wp-content/uploads/2018/11/BCM-2018-09-Sep.pdf

[Jim Blackwood]

Sometimes I buy that argument, sometimes I don't. Early adopters always pay a premium and for high rollers that's easily justified. For the rest of us, not so much and there are always other alternatives.

But a good suggestion and appreciated. At some point it's likely to be where it's price does make sense for everyone. I'm just wondering if it's gotten there yet.

Jim

[Gary Hatt - Publisher BCM]

Sometimes I buy that argument, sometimes I don't. Early adopters always pay a premium and for high rollers that's easily justified. For the rest of us, not so much and there are always other alternatives.

But a good suggestion and appreciated. At some point it's likely to be where it's price does make sense for everyone. I'm just wondering if it's gotten there yet.

Jim

I am not that familiar with his prices Jim.  Give him a call and he may work with you depending on how much you buy.  His prices may have come down since you last looked.

Gary

[richard5933]

... I plan on using 1/4 marine ply then 3.5 inch closed cell foam board then 1/2 inch tongue and groove underpayment and vinyl plank flooring.   My hope is the floor will be solid without having to run a bunch of furring strips in the floor.  THe compression rating on the foam is very high.  What are your thoughts?

Two thoughts:

I'd use something beefier than 1/4" on the bottom layer for two reasons. 1) In the future you will be screwing things to the underside of the floor, and 1/4" plywood will not hold. There are just too many things that will need to be mounted to the ceiling of the bays to imagine you'd never need to do this. 2) No matter how much resistance the foam has to compression, it will compress. The 1/4" plywood will not provide much help and will bow between the supports over time. My suggestion would be to use the 1/2" on the bottom layer as well.

Is the 3-1/2" foam layer necessary? Heat rises and most of the heat loss will be through the walls and ceiling. Seems like a foam layer that thick might present stability problem for whatever is mounted above it.

Of course, if you do go with the 3-1/2" thick foam layer, you'd be able to put in some decent sized wire chases front-to-back by incorporating a few well-placed large conduits in channels cut into the bottom of the foam.

[Jcparmley]

That's a great point about the thickness of the bottom layer.  I will add at least 1/2 inch.  The reason I want that much insulation is:

1.  I already have the insulation
2.  I am raising the roof so I won't loose headroom
3.  I want to be able to use the bus in colder climate
4.  I want to put less load on the HVAC

Richard, is your bus set up for winter use? 

Two thoughts:

I'd use something beefier than 1/4" on the bottom layer for two reasons. 1) In the future you will be screwing things to the underside of the floor, and 1/4" plywood will not hold. There are just too many things that will need to be mounted to the ceiling of the bays to imagine you'd never need to do this. 2) No matter how much resistance the foam has to compression, it will compress. The 1/4" plywood will not provide much help and will bow between the supports over time. My suggestion would be to use the 1/2" on the bottom layer as well.

Is the 3-1/2" foam layer necessary? Heat rises and most of the heat loss will be through the walls and ceiling. Seems like a foam layer that thick might present stability problem for whatever is mounted above it.

Of course, if you do go with the 3-1/2" thick foam layer, you'd be able to put in some decent sized wire chases front-to-back by incorporating a few well-placed large conduits in channels cut into the bottom of the foam.

[richard5933]

...Richard, is your bus set up for winter use?

Yes and no. I can easily keep the inside warm when plugged into shore power with outside temps in the 20s using the electric heaters. I've also got a propane furnace, but I'm guessing that it would struggle a bit at temps that low.

The insulation in the main bus is adequate, not great, but adequate. The bays are not insulated, however, so I'd have to run the electric heat in the wet bay to keep that from freezing. That works when parked and on shore power or generator. There is a vent from the LP furnace as well in the wet bay.

For some reason, Custom Coach did not tap into the OTR heater for the wet bay, so keeping the bay warm while on the road is the problem right now. It's on my list - hopefully I can just cut a hole through the ceiling of the bay on each side of the bus to bring some of the air flow down from the main OTR heat ducts which run along the sides of the passenger compartment. That's what they did on our 4106, and I hope that it would work on the 4108 as well.

[TomC]

Floor insulation is mostly to prevent heat from raising into the bus. I left the standard 1" plywood with 1/4" rubber mat (transit bus) and have had no issues with heat or cold. Most important is side and roof insulation along with double pane windows. Good Luck, TomC