| Foam insulation [message #347273] |
Tue, 03 September 2019 11:55  |
Rich Kinas
Messages: 113
Registered: July 2019
Karma: 1
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Senior Member |
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Hey all,
Working on the floors in my 76 Elaganza. The second sheet of flooring plywood (from the front) had a significant bowing upward in the center. This had to be fixed (actually I'm replacing all the floor) so that I could start on the interior rebuild. So to inspect what was causing the issue I took my Skill saw, set the blade to just under the thickness of the plywood and made a cut from side to side about 3 inches from the rear edge (8' side). I then just used a screw driver to pop this section of plywood off (much of it actually just fell apart from previous water damage). Anyway what I discovered is that there is foam between the aluminum cover protecting the bottom of the plywood and the plywood, to the point it looks as though the foam is what has caused the floor to buckle upward. The interesting thing is that the the original Norcold frig that I just removed a few weeks ago had all of its insulating foam expand (over the years ?) to the point the doors would no longer shut and it split all the interior plastic by pushing it inward. Also this frig would not come out since the sides were swelled out as well. Hmmm....so it looks like old foam continues to expand (at some constant rate, or accelerated because of temperature, etc ?) Does this sound reasonable. Also then do others have foam between the bottom aluminum and the floor plywood.
Thanks as always...
Rich Kinas
76 Elaganza II
Orlando, FL
Rich Kinas
1976 Elaganza II
Orlando, FL
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| Re: Foam insulation [message #347351 is a reply to message #347273] |
Wed, 04 September 2019 21:08  |
Rick Staples
Messages: 126
Registered: May 2014
Location: Johnstown, Colorado, USA
Karma: -1
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Senior Member |
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Rich,
I believe the aluminum-shielded foam insulation was standard on all coaches after 1973. Makes floor warmer/cooler, quieter, and less likely to scorch above mufflers. Glad I have it.
Since the aluminum is fairly thin and not supported by anything below, I wouldn't expect it to exert much upward pressure on the floor if it did expand. But then, I've never heard of old foam insulation expanding years later either. Maybe something to do with the extreme humidity of Florida?
Rick Staples
Rick Staples, '75 Eleganza, Johnstown, CO
"Advice is a dangerous gift, even from the Wise to the Wise, and all paths may run ill." -Tolkien
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| Re: [GMCnet] Foam insulation [message #347410 is a reply to message #347366] |
Thu, 05 September 2019 18:15 |
Jimmy_Bonez
Messages: 105
Registered: September 2017
Location: NH
Karma: 0
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Senior Member |
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It’s unlikely that the foam continued to expand over the years. Foam insulation has been used in automotive and residential house applications for years with no such expanding. What is more likely happening is that water has got into the floor which you explained and it has expanded with heating and cooling temperatures. Which is probably the case with fridge as well condensation building up from a crack or poor air flow. Using any sort of new spray foam kit or can will not expand over time. Imagine all the houses with completely spray foamed walls and having to worry about the foam expanding cracking all your dry wall. Not going to happen. Use the new foam as directed and you’ll be worry free
Sent from my iPhone
> On Sep 5, 2019, at 6:54 AM, Rich Kinas via Gmclist wrote:
>
> I've been researching online to see if there is any information about the expanding foam years after it was installed. My original Norcold frig had
> this in a bad way and is why everyone has such a difficult time in replacing them, the clearance on the sides was tight before the foam extra
> expanded, and once expanded it wont come out without a fight! However I am not finding much if any information on this issue. My only concern is the
> rate of additional expansion for the original, but mostly for newer foams that I am planning on using to replace the original. I am going to follow
> what Justin did and bring the original insulating foam up to a full wall thickness to help with sound, temp, etc. this includes these floor sections
> and I guess I'm just going to stop worrying about it. I just would prefer that if I bring all the walls, floors up to full thickness (shaving off the
> high spots) that 10 years down the road my walls are not bulging inward :)
>
> Rich
> --
> Rich Kinas
> 1976 Elaganza II
> Orlando, FL
>
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Jim DeMellia and Jen Radefeld and our cat Ickis
NH natives
1975 GMC “Palm Beach” ,455, her names Linda
Full time RVers exploring the beautiful and unusual parts of the country.
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| Re: Foam insulation [message #347420 is a reply to message #347273] |
Thu, 05 September 2019 21:13 |
GatsbysCruise
Messages: 261
Registered: January 2017
Location: Waukegan, Illinois
Karma: 3
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Senior Member |
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This is interesting.
My Norcold is over 20 years old. roughly 7 years ago, my GMC fridge died. As I still had the Norcold from the old scuttled RV, I modified the cabinet to take the extra depth of the Norcold Body.
I had no problem with the Norcold, no expanded foam, no pushed out panels, actually, Nothing!
I also used expanding foam when I sealed windows and doors in the house. The expansion was at the time I applied it and after 15 years, non of it has continued to expand.
May be possible that there was a miracle, and GM applied a bit too much and it had to expand somewhere. I say miracle because if you saw the little bit of foam on my walls and ceiling, you'd understand why this doesn't sound right to me.
But I guess it depends on who fitted it out and if they added more foam insulation.
GatsbysCruise. \
74GMC260 Former Glacier Model style. \
Waukegan, Illinois \ Keep those MiniDiscs Spinning \ MY GREYHOUND IS FASTER THAN YOUR HONOR ROLL STUDENT \ WindowsXP-Win7-Win8.1-UBUNTU STUDIO - UBUNTU VOYAGER - Berzin Auto Center
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| Re: Foam insulation [message #347428 is a reply to message #347420] |
Fri, 06 September 2019 04:01 |
Rich Kinas
Messages: 113
Registered: July 2019
Karma: 1
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Senior Member |
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Hmm....the great mystery. I agree that the original foam insulation (or more appropriately lack there of) seems to be fine everywhere else on the coach. I'll take some pics today so that everyone can see what I am talking about.
Rich
Rich Kinas
1976 Elaganza II
Orlando, FL
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