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Old 06-09-2024, 12:44 PM   #1
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Anyone seen this strapping method?

I just bought a 2001 Thomas MVP pusher. Previous owner gutted it and had started initial stages of the conversion. Has anyone seen strapping done on the roof channels like this? They used the pink insulation board then two layers of wood. On the sides, thereís a piece of wood on either side of the hat channel which looks like it will expose a lot of thermal bridging. Iím considering pulling this all out and starting over. Any reason I shouldnít? Photos for reference.
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Old 06-09-2024, 02:45 PM   #2
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The wood under the side windows, I would just leave that alone, maybe fill in the space with more insulation.

The roof, hard to tell what is going on there as the pic is sideways and really does not show much....

Before we make any suggestions on the roof, what was your plan/idea on attaching materials to the ceiling ?

What your vision on the ceiling build ???
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Old 06-09-2024, 03:43 PM   #3
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I have less issues with the ceiling than under the windows. I don't like wood against metal with nothing to blanket the steel from condensating. This build probably planned to cut out the chair rail. Otherwise there is no benefit of their wall strapping. I would remove it and add horizontal plywood strapping. The ceiling is kind of a waste. You can accomplish the same thing with blocks into the side but keep the ceiling height same as factory. If you can afford loosing 1.5inches of extra ceiling, then add strapping from front to back and let the spray foam wrap the hat channel for 95% coverage.
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Old 06-09-2024, 03:47 PM   #4
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Quote:
Originally Posted by evergreens View Post
I just bought a 2001 Thomas MVP pusher. Previous owner gutted it and had started initial stages of the conversion. Has anyone seen strapping done on the roof channels like this? They used the pink insulation board then two layers of wood. On the sides, there’s a piece of wood on either side of the hat channel which looks like it will expose a lot of thermal bridging. I’m considering pulling this all out and starting over. Any reason I shouldn’t? Photos for reference.
I think it would do the opposite for the thermal bridge. This would provide separation from the metal and allow for insulation behind the wood. Spray foaming would also provide a vapor barrier. It may be possible to add foam board to the side assembly to better provide separation from the metal.
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Old 06-09-2024, 07:55 PM   #5
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Yeah I donít know why they uploaded sideways. Just mentally imagine that being the ceiling. Iím focused on the hat channel that has a strip of the pink insulation board, then two layers of 3/4x2 nailed in with finishing nails.

I havenít fully decided on a ceiling style yet, but I do plan to spray foam the bus. What bothers me is with all the research Iíve done so far I havenít seen anyone recommend this method. I can tell that there would be no way to run any wiring across the ceiling without first going to the sides there the existing bus wires run, then back up to the roof.

Iíve watched Chuck Cassidyís framing theory to avoid thermal bridging. Iíve also seen other examples that follow the hat channel and allow for tongue and groove ceilings. What I care about first and foremost is a well insulated rig. Form follows function for me.

Again, just bought the bus and in floor planning right now.

Quote:
Originally Posted by ewo1 View Post
The wood under the side windows, I would just leave that alone, maybe fill in the space with more insulation.

The roof, hard to tell what is going on there as the pic is sideways and really does not show much....

Before we make any suggestions on the roof, what was your plan/idea on attaching materials to the ceiling ?

What your vision on the ceiling build ???
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Old 06-10-2024, 11:01 AM   #6
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Curved roof furring strips

I installed curved roof furring strips on my roof ribs with TEKS screws. I cut 1/2 inch cdx plywood into 3.5 inch wide strips (across the 4 ft dimension, because it bends easier that way), and laminated 2 layers onto the ribs to give 1 inch thickness. I put them in after spray foaming the roof to the depth of the ribs and trimming the foam. Then I added 1 inch very flexible white mylar-faced styro board in between the ribs to achieve 3 inch insulation thickness. The strips were wide enough for me to screw the longitudinally-oriented T&G pine ceiling boards off the ribs to avoid thermal bridging. The level of insulation seems sufficient - no condensation on ceiling or screw heads, bus stays warm on 16 deg F nights.

For wall furring, since the seat rail is 1 inch wide, I used 1 inch furring horizontally. I put in 2 inch pink/blue board between ribs, and 1 inch between furring strips. Then clad the walls where there weren't windows with 1/2 inch cdx.

The vertical wood I see in the photos aside the between-window ribs doesn't make sense to me - I would prefer insulation there - but I wasn't worried about losing an inch and a half of width on each side.
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Old 06-11-2024, 06:06 AM   #7
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Originally Posted by Ross View Post
I installed curved roof furring strips on my roof ribs with TEKS screws. I cut 1/2 inch cdx plywood into 3.5 inch wide strips (across the 4 ft dimension, because it bends easier that way), and laminated 2 layers onto the ribs to give 1 inch thickness. I put them in after spray foaming the roof to the depth of the ribs and trimming the foam. Then I added 1 inch very flexible white mylar-faced styro board in between the ribs to achieve 3 inch insulation thickness.
If Iím picturing this correctly, your layers are:

metal
furring strip
T&G

And your furring strips go the same direction as the ribs? Similar to my picture minus the pink board sandwiched between?

Any reason why you stacked spray foam and styroboard instead of spray foam the full three inches?
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Old 06-11-2024, 12:10 PM   #8
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why styro?

Evergreens,
The reasons I stacked styro board below spray foam are:
I wanted wood furring strips to attach my ceiling T&G to.
The styro board would bend enough to do the job, and had a mylar face, which, when I taped the seams, gave me a vapor barrier.
The styro board with mylar that I could find was 1 inch thick, and 2 layers of 1/2 inch plywood would bend well enough to work, and I already had the plywood scraps.
I wanted more insulation than just 2 inches of spray foam.
The steel ribs gave me a good guide for trimming the spray foam.
I did the spray foam before installing the furring strips.
I ran all my 12 vdc house wiring down the passenger side wall, and needed space to get wires to the ceiling lights and fans.
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Old 06-11-2024, 08:53 PM   #9
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Evergreens,
The reasons I stacked styro board below spray foam are:
I wanted wood furring strips to attach my ceiling T&G to.
The styro board would bend enough to do the job, and had a mylar face, which, when I taped the seams, gave me a vapor barrier.
The styro board with mylar that I could find was 1 inch thick, and 2 layers of 1/2 inch plywood would bend well enough to work, and I already had the plywood scraps.
I wanted more insulation than just 2 inches of spray foam.
The steel ribs gave me a good guide for trimming the spray foam.
I did the spray foam before installing the furring strips.
I ran all my 12 vdc house wiring down the passenger side wall, and needed space to get wires to the ceiling lights and fans.
Cool thanks for all the details!
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