Interior wall thickness

[mike802]

Here is a video showing what I have done, and the second one showing what I am doing.  I dont know how this is going to work out, but we do not plane on using the bus in winter conditions. 

MC9 wall insulation finished

Bedroom paneling

[Uglydog56]

My interior walls are 2x4's turned the other way, clad with 1/4" plywood, and filled with polyisocyrunate.  This makes them 2" thick.  Currently the receptacles are just screwed to the plywood, but as I rewire, I'm putting them all in shallow boxes. 

[chev49]

for my current bus, I am used 3/4 X 2 inch strips on edge, and most walls with 1/2 plywood. I got around 200 of these from my neighbor who had them saved from a furniture shop years ago. In the past, I started off with 2x4's then 2x2's in later bus, and 1 1/4 in sq tubing. I have seen some built with the 2x4 metal studs for commercial work.

I think the easiest for me to do was this last bus, and they are screwed together so i can take it apart if i wanna change something.

[Scott & Heather]

We love wood! 

[Bill B /bus]

Exterior surfaces are two layers of 1/4" Luan. The second layer is glued to the first to make the thermal break. Insulation is your choice. My preference would be foam application. Interior walls can be as thin as 3/4" ply. 7 ply would be best.  You don't need to stud walls. Why waste the space?

Bill

[artvonne]

  3/4 plywood has an R value about equal to a single pane of glass and weighs 40 pounds a sheet, whereas 3/4 foam or fiberglass could be R4 or higher and weighs almost nothing. 30 sheets of 3/4 ply could add as much as 1200 pounds to a 40 foot Bus. Maybe not much to some, but should be considered as part of the overall "package". The outer walls of a Bus are quite strong, and as most noise will come up from the floor, and most heat will flow in or out through the walls and ceiling, I personally dont see the need for heavy plywood walls. 1/8 or 1/4 inch paneling or tongue and groove strip should be very solid. And while foam panels and spray are quite popular, once aged a few years its not a great deal better in R value than fiberglass.

  Interior walls do not need to be 4 inches thick. Wood or hollow steel 2/4's set sideways, would be more than sufficient. Running all electrical wire in conduit during the construction phase could help a great deal later on if there is any wiring issue.

  3 inches of fiberglass in the ceiling could give you R 15 plus. OTOH, foam might reach as high as R 21. The foil back insulation can add as much as R 2 to the insulation, not sure what an outer foil film, combined with an inner film would do.

  I personally have some strong concerns with any foam insulation in direct contact with steel framing and the foam filling of structural frame tubing. This was done on steel buildings years ago and is no longer recommended due to severe corrosion issues due to condensation. Any moisture that gets inside the wall will be trapped if the wall cannot breathe. By the time any damage is seen externally, the structure can be greatly compromised. Fiberglass may not be superior to foam in the short term, but after foam has aged 5 or more years it appears to become much more equal to fiberglass. That some of these Buses are still rolling down the road after 30, 40, and some 50 years old or more with fiberglass insulation should be duly noted. I do understand the sound issues though. My fear is that foam could do to Buses, what fiberglass epoxy did to wood boats in the 60's. Yes, if water gets fiberglass wet it can also cause rust, but I am speaking only about natural condensation, not water leakage.

  But hey, its your Bus, do it the way you want.

[Van]

 

[robertglines1]

See we brought up a old but common subject of heat transfer and condensation. Any thing you can do to keep moist air from getting to cold metal will help this condensation . Foil faced insulation helps give you a higher r factor with less thickness. Can't see where moisture would enter a filled cavity that is also insulated over also.:Anything is possible. More is better in the beginning in this case (insulation). Don't forget ceiling of bays-any area you can possibly get to.  Happy bussin  Bob-enjoying vacation at the Flywheelers.

[Jeremy]

...what fiberglass epoxy did to wood boats in the 60's.

Curious to know what you're referring to by this. Possibly people sheathing wet wood with fibreglass and finding that it didn't work - but that's hardly the fault of the fibreglass. Incidentally, in the '60s few boatbuilders would have even heard of epoxy, and even today the vast majority of resins that are used with fibreglass in boats are polyester or vinylester resins, not epoxy. Epoxy resins are widely used in wooden boat construction, but that's as a timber adhesive and not associated with laminating fibreglass.


By the way, if anyone's interested, my bus has two interior walls - one's 3/4" plywood faced with veneered 4mm plywood, and the other one is constructed from a frame of 1" steel box section with 4mm plywood facings on both sides and foam filling the void in the middle. The reason for using steel for this wall is that it's curved - this wall is one end of the bathroom, and the shape of the wall is the mirror image of the shape of the quadrent shower enclosure that forms the other end of the bathroom. Creating the same curve using wood would have made the wall thicker than I wanted.

Jeremy

[artvonne]

...what fiberglass epoxy did to wood boats in the 60's.

Curious to know what you're referring to by this.
Jeremy

  The advent of fiberglass resin in the 50's spawned a whole era of new boat manufacturing and repair. Where wooden boats had always been stripped and refinished with high quality varnishes, fiberglass resin was being touted as the last coating you would ever have to put on your boat. Almost every wooden boat ever built or owned in North America was redone with fiberglass in the 50's and 60's, some quite beautifully. Many came out of factories brand new finished that way. It took well over 10 years before the problems were really getting attention, and by then it was already to late for many of the older classics.

  It didnt matter how dry the wood was when it was sealed, any moisture that got behind the resin stayed there, whether from water splashing inside the boat, or a scratch or blemish in the hull from a rock or dock strike. The wood couldnt breathe. From the outside of the hull, the resin looked hard and solid. From inside, the structure looked fine as well. But black spots began to appear under the outer finish. Soon blisters appeared. No big deal, strip the glass off and fix it, right?

  Wrong. By the time people saw problems that warranted major refinish work, there wasnt anything left to refinish. Not only would most of the outer hull wood be rotted, the rot generally had gone into all the lower framing members. Huge numbers of classic and very beautiful Chris Crafts and Hackers and various other wooden boats and yachts were left sitting out there existence in boat yards and back yards slowly rotting away. I saw many where the engines had fallen right through the hull after everything let go, so rotted you couldnt get the boat on a trailer without it crumbling away. They are gone. And a lot of the early all fiberglass boats are gone as well, because they used wood engine bunks and framing encased in fiberglass that sooner or later rotted away inside the cavity. This wasn't a fault with the fiberglass, its great stuff. It was simply that nobody knew exactly the correct way to use it because the problem had never been experienced. Even as the boats were rotting away in boat yards in the 70's, many boat shops continued to deny the problem had anything to do with glassing over the wood, and many continued doing it well into the late 70's and early 80's. If it hadnt been for the massive inflation of classic boat values in the late 80's and 90's, many of the older wooden boats would likely have winked out of existence.

  I think its really neat to see people trying to preserve what few remain. My ex Brother in Law has been trying to restore a 24 foot '51 Hacker Craft for about 10 years, says he's replaced nearly 70% of the wood and hopes to get her out this summer.

  I'm not trying to make something out of nothing, just hoping we dont do that same thing to Buses through some technology we havnt the long term knowledge and experience to know how it will react.

[Jeremy]

I suspect you've re-written the history of boatbuilding there. Fibreglass sheathing is an entirely satisfactory process and not some mistake which ruined boats for decades. And talking about scratches letting water in, or 'black sports appearing under the outer finish' suggests that you're confusing fibreglass sheathing - which is a tough, thick and opaque layer - with varnish or lacquer.

It is possible that in the early days fibreglass resin (without fibreglass) was touted as some sort of permanent replacement for varnish, but this would be a different application to fibreglass sheathing; either way, suggesting that serried ranks of classic boats crumbled into nothingness as a result of fibreglass being applied to them is imaginative exaggeration.

Jeremy

[Brassman]

I do believe Paul is right, but that's boats not buses.

[Jeremy]

Yeah, maybe he is. I was a professional boatbuilder in a previous life, but who knows how those epoxy fumes have affected me


Jeremy

[Brassman]

I have seen fiberglass boats that have used plywood as the core material turn into fiberglass bags.

[artvonne]

I suspect you've re-written the history of boatbuilding there. Fibreglass sheathing is an entirely satisfactory process and not some mistake which ruined boats for decades. And talking about scratches letting water in, or 'black sports appearing under the outer finish' suggests that you're confusing fibreglass sheathing - which is a tough, thick and opaque layer - with varnish or lacquer.

It is possible that in the early days fibreglass resin (without fibreglass) was touted as some sort of permanent replacement for varnish, but this would be a different application to fibreglass sheathing; either way, suggesting that serried ranks of classic boats crumbled into nothingness as a result of fibreglass being applied to them is imaginative exaggeration.

Jeremy

 Dude, I am not confused about anything. I lived in the land of 14,000 lakes for over 50 years and have bought, sold, owned and worked on boats all my life. Chris Craft Boats were built on Lake Minnetonka in Wayzata Minnesota were my Father grew up. There were at one time, 100's of boat manufactures in Minnesota, Minnesota has the highest number of boat owners per capita in the world, approx one boat for every 7 Minnesotans. Many people who live on or near lakes have more than one boat. I can assure you, knowledge of wood boats in Minnesota is as high, and likely higher than anywhere in the world, and old wood boats have dissolved like clouds on a windy day. Not from natural rot and decay, but from covering the damn things with fiberglass. Every wood boat shop I ever knew was talking about this 40 years ago when I was a kid, if you never heard of it you likely dont know anything about the subject. All the High Schools had kids building wood boats when I was growing up. Often beautiful Cedar Strip Canoes, then covering them with cloth and resin. If you dont believe that will destroy a boat in short order, you simply havnt seen it or been around it.

 I have been in many boat yards in Minnesota, some filled with 100's of old wooden boats that will never, ever see the water. There are, and were, really old boats from the the 1800's through the 1940's and 50's, from little row boats to 40 plus foot Yachts, that survived for decades with normal and occasional refinishing and maintenance, that simply dissolved once encased in Fiberglass, and disappeared. I actually witnessed a neighbor fiberglass his Grandfathers old wood row boat, a boat built well before WW2, in around 1969. By the time I started driving in 1974, the boat was completely ruined, the entire bottom nothing but rotted goo. I should probably also add that there were several guys up there who had full time jobs replacing wood transoms in fiberglass boats, for all the same reasons.

 I dont know why you always come across like you think im stupid or making things up, but its becoming rather tiring, Jeremy.