Journey with Confidence RV GPS App RV Trip Planner RV LIFE Campground Reviews RV Maintenance Take a Speed Test Free 7 Day Trial ×
 


Reply
 
Thread Tools Search this Thread Display Modes
 
Old 01-26-2004, 01:14 PM   #1
3 Rivet Member
 
Join Date: Oct 2003
Posts: 132
Images: 2
Lightbulb Under floor insulation

When I removed the belly pan and fiberglass insulation, I thought I would replace the fiberglass with "styrofoam" insulation.

I've got two questions:

1. Is using this type of insulation a good idea for this application? and

2. I plan to screw it in place by driving a screw (complete with wide washer) through the insulation and into the flooring about one quarter of an inch. Is this a good idea assuming number one is acceptable?

Rick
Rick Alston is offline   Reply With Quote
Old 01-26-2004, 01:22 PM   #2
Rivet Master
 
Chas's Avatar
 
Austin , Texas
Join Date: Oct 2002
Posts: 949
Images: 22
Other than it being HIGHLY FLAMMABLE I don't see a real problem, at least it won't soak up the bellypan water.

Ahh yes, those were the days, poking around into the bowels of an Airstream floor, rotted steel & wood, snakeskins and other assorted varmints.

Kinda enjoying my time off from Airstreams for a while but I feel the bug still within me, damn it, just can't seem to shake it!!

Chas
Chas is offline   Reply With Quote
Old 01-26-2004, 01:22 PM   #3
Rivet Master
 
TomW's Avatar
 
1967 26' Overlander
Huntsville , Alabama
Join Date: Dec 2003
Posts: 3,022
Images: 4
Breathing

Someone in a previous post, indicated the floor needs to breathe. How much, I don't know. I'm in a similar situation as you right now, and hope someone posts a good answer.

Was cost a consideration to you? While it won't break the bank, it seems styrofoam would be more expensive.
TomW is offline   Reply With Quote
Old 01-26-2004, 01:37 PM   #4
3 Rivet Member
 
Join Date: Oct 2003
Posts: 132
Images: 2
Cost is not yet a consideration.

Chas-

Perhaps my use of the term "styrofoam" is too loose. When I say "styrofoam", I mean housing grade insulation which is approved for installation in residential and commercial buildings. Every time I pass a constructions site I see either pink or blue insulation boards in 4X8 sheets (about 3 inches thick) and think how nice that might work under the floor.

Rick
Rick Alston is offline   Reply With Quote
Old 01-26-2004, 01:40 PM   #5
Contributing Member
 
Pahaska's Avatar
 
2018 Interstate Grand Tour Ext
Austin (Hays County) , Texas
Join Date: Jun 2002
Posts: 7,164
Images: 4
Another suggestion

On a previous SOB, I used the foil-bubble-foil stuff stapled in place. I understand Airstream now uses this material on Limited models with slideouts. The stuff is light and can't soak up water. The fact that Airstream is using it says it should be safe for the floor.

I can vouch for the efficiency of the foam-bubble-foam stuff. My whole Scamp was lined with the stuff and it was a super snug trailer.
__________________
John W. Irwin
2018 Interstate GT, "Sabre-Dog V"
WBCCI #9632
Pahaska is offline   Reply With Quote
Old 01-26-2004, 01:47 PM   #6
Rivet Master
 
Ken J's Avatar
 
1956 22' Flying Cloud
Durango , Colorado
Join Date: Sep 2002
Location: 1975 25' Tradewind
Posts: 3,499
Images: 14
This may be unpopular - but what I do is take out the insulation and I don't put anything back - I figure all it does is hold moisture.

Ken J.
Ken J is offline   Reply With Quote
Old 01-26-2004, 02:11 PM   #7
3 Rivet Member
 
Join Date: Oct 2003
Posts: 132
Images: 2
John

I think we are discussing the same type of generic foam insulation. I like the idea that it won't hold water, too.

Ken

I've got to admit that I, too, thought of not replacing the insulation. I have never camped below 31 degrees, so I don't think I need all that added insulation. However, the next owner may want the added protection. Since re-insulating the unit is pretty simple, I will go ahead and do it.

I am intrigued by the issue of the flooring needing to breathe. That sounds reasonable, but does it breathe adequately from the other side? What about laying down floor tiles with glue? I have a feeling that the breathing issue may not be as strong a concern as some people think.

Rick
Rick Alston is offline   Reply With Quote
Old 01-26-2004, 03:33 PM   #8
Rivet Master
 
Janets Husband's Avatar
 
1977 Argosy Minuet 6.0 Metre
1964 26' Overlander
1977 25' Tradewind
Eastern , Washington
Join Date: Jan 2004
Posts: 865
Images: 6
I'm sort of thinking like Rick on this subject, but I'm not really sure.
I have a few questions I can't seem to clear up in my mind.
Conventional thinking on insulation is
a.] The vapor barrier goes toward the heated side.
b.] Insulation should have adequate ventalation on one side to keep it dry
The question is if the insulation is between the floor and the belly pan where is the "vapor barrier" and where is the "air space" for ventalation?
This brings up another question: If your insulation gets wet for what ever reason does it not dry out by the water vapor going through the wood floor? Does this cause rot?
Is there a better way, maybe styrofoam?
Nothing clear in this head.
__________________
Peace
Gary
Janets Husband is offline   Reply With Quote
Old 01-26-2004, 03:45 PM   #9
Rivet Monster
 
wahoonc's Avatar

 
1975 31' Sovereign
1980 31' Excella II
Sprung Leak , North Carolina
Join Date: Jun 2003
Posts: 7,172
Images: 40
My take on this is that the belly pan is not sealed air tight, also with the tank connections and vent stacks and what have you going thru the floor, there are plenty of opportunities for vapor to escape. I like the idea of a vapor barrier, but wonder if it is necessary. I like the idea of the batt insulation only because it is easy to stuff around things. The styrofoam (FWIW know as extruded polystyrene) has the advantage of not absorbing water, doesn't lend itself well to nesting critters and won't absorb and hold odors. Downfalls; it is quite noxious if burned, and being ridgid is hard to fit in and around things. That being said...want to guess what I insulated the roof of my house and barn with?

Aaron
wahoonc is offline   Reply With Quote
Old 01-26-2004, 03:55 PM   #10
Rivet Master
 
Ken J's Avatar
 
1956 22' Flying Cloud
Durango , Colorado
Join Date: Sep 2002
Location: 1975 25' Tradewind
Posts: 3,499
Images: 14
I've been in my trailer down to about 10 degrees and did not seem to miss the insulation...

As far as breathing goes what that refers to is you don't want your belly 100% sealed - it should breathe - otherwise any mositure in there would stay there + you would get condensation.

This was something I had concerns with several years ago because the belly on my 59 was not 100% sealed - I was told not to over vulcum........

Ken J.
Ken J is offline   Reply With Quote
Old 01-26-2004, 03:57 PM   #11
Rivet Master

 
, Minnesota
Join Date: Aug 2003
Posts: 7,721
Images: 59
R-value

Aaron: I think it's the other way, expanded polystyrene (3.8) has a higher R-value than fibreglas (3.2). Extruded polystyrene R-value is 4.8, and sprayed polyurethane R-value is 5.9.
markdoane is offline   Reply With Quote
Old 01-26-2004, 03:59 PM   #12
Rivet Master
 
Chas's Avatar
 
Austin , Texas
Join Date: Oct 2002
Posts: 949
Images: 22
The problem is along the lower seam, behind the rubrail, water comes in quite easily.

From the factory they are somewhat sealed with double edge tape which holds for maybe a few months, perhaps a couple of years. If any of the flooring is exposed anywhere near this seam the water wicks into the plywood and you have rot. Then insulation gets wet also and further contributes to the problem. Aluminum starts corroding at the rivets and then the belly starts falling off while the steel framing turns to rust.

The more I think about it the recent AS models had a lot going for them with the abscence of a bellypan. If I had anothe Airstream I would pull all the insulation out and put a bunch of "soffit-like vents" in the bellyskin, keeping it well aired out.

Chas
Chas is offline   Reply With Quote
Old 01-26-2004, 04:06 PM   #13
Rivet Monster
 
wahoonc's Avatar

 
1975 31' Sovereign
1980 31' Excella II
Sprung Leak , North Carolina
Join Date: Jun 2003
Posts: 7,172
Images: 40
Re: R-value

Quote:
Originally posted by markdoane
Aaron: I think it's the other way, expanded polystyrene (3.8) has a higher R-value than fibreglas (3.2). Extruded polystyrene R-value is 4.8, and sprayed polyurethane R-value is 5.9.
OOPS I was thinking of Expanded Polystyrene.

Aaron
wahoonc is offline   Reply With Quote
Old 01-26-2004, 05:34 PM   #14
3 Rivet Member
 
Cruiser's Avatar
 
1952 25' Cruiser
Dummerston , Vermont
Join Date: Sep 2002
Posts: 169
Images: 45
I used 2" polyisocyanurate rigid insulation with foil backing under our newly installed floor. I used panel adhesive with a few screws as you propose to hold it in place overnight. The stuff has less noxious off-gassing than polystyrene, it doesn't absorb water, and it has high R-values (7-10). I used spray foam in cracks around edges of panels with advice from Geof to increase R-values further. It was tedious cutting and fitting the polyisocyanurate insulation into so many odd sized panels. I used 1-1/2" in the walls and managed to get it to bend okay. The trailer didn't heat up nearly as much in the hot sun last summer (no A/C). Might make a difference in the floor, too, if you're on hot pavement?
Doug
Cruiser is offline   Reply With Quote
Old 01-26-2004, 07:49 PM   #15
Rivet Master

 
, Minnesota
Join Date: Aug 2003
Posts: 7,721
Images: 59
Insulation

Doug:
Shame on you! Tell us how neat it is (isocyan' w/foil) and don't tell us where to get it or what it cost.
markdoane is offline   Reply With Quote
Old 01-26-2004, 08:35 PM   #16
Rivet Master
 
Davydd's Avatar
 
Tonka Bay
Join Date: Aug 2003
Posts: 770
Images: 13
Don't use expanded polystyrene

Aaron,

Expanded polystyrene (compressed polystyrene beads) will hold water between the beads. Extruded will not absorb water. Also, I know for a fact that critters will attack polystyrene in any form. I have extruded closed cell polystyrene enveloping my entire house protected on the interior side with 2" T&G pine boards. At night I can hear the mice in the insulation. Luckily they've never penetrated the pine and gotten into the house. BTW, if the boards are white they are expanded polystyrene. If the boards are blue (Dow), pink (Owens Corning) or yellow (Certifoam) they are extruded closed cell polystyrene.

Doug's idea of using polyisocyanurate boards with an aluminum foil vapor barrier is commonly used in commercial roof insulation. They can, by code, be applied directly over a metal roof deck without a fire barrier. Polystyrenes require a gypsum board fire barrier. The foil faced type of boards can be used inside a building with the foil on the warm side. Polyisocyanurates are very similar to polyurethanes, are closed cell non water absorbing--and safer than polystyrene.
__________________
Davydd
2015 Sprinter Class B Camper Van
(Former 1971 vintage Airstream Owner)
Davydd is offline   Reply With Quote
Old 01-26-2004, 08:47 PM   #17
3 Rivet Member
 
Cruiser's Avatar
 
1952 25' Cruiser
Dummerston , Vermont
Join Date: Sep 2002
Posts: 169
Images: 45
Did I mention I'm a distributor? (just kidding) I found polyisocyanurate insulation in several sizes at our local small town home center/ lumber yard. I've seen it at the big box stores, too. Some of the sales folks have never heard of it, even though they carry it. I think the problem is that none of us know how to pronounce it. You may have to do some explaining for folks to know what you're talking about. I can't remember what I paid - didn't think it was too expensive, maybe $10 or $15/ 4'x8' sheet.
Doug
Cruiser is offline   Reply With Quote
Old 01-26-2004, 08:58 PM   #18
Rivet Master
 
Davydd's Avatar
 
Tonka Bay
Join Date: Aug 2003
Posts: 770
Images: 13
Polly I so sigh an your ate

I think that is phonetically close.
__________________
Davydd
2015 Sprinter Class B Camper Van
(Former 1971 vintage Airstream Owner)
Davydd is offline   Reply With Quote
Old 01-26-2004, 09:02 PM   #19
Rivet Master
 
LOST , Hawaii
Join Date: Jun 2002
Posts: 2,193
One of the trade names is Thermax, made by Dow; I have seen it at HD and Lowes. I also used under my floor and really like the way it went in and it doesn't hold water.

John
74Argosy24MH is offline   Reply With Quote
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools Search this Thread
Search this Thread:

Advanced Search
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

Disclaimer:

This website is not affiliated with or endorsed by the Airstream, Inc. or any of its affiliates. Airstream is a registered trademark of Airstream Inc. All rights reserved. Airstream trademark used under license to Social Knowledge LLC.



All times are GMT -6. The time now is 09:59 PM.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.