I’m in the process of doing a complete makeover on a 2006 Holiday Rambler Admiral before hitting the road for an extended period. The interior walls and ceiling were a bit dated. While it is opened up, I plan on improving the insulation. The exterior is fiberglass end caps with aluminum walls and a fiberglass roof. The present insulation consists of fiberglass and styrofoam. Does it require a vapor barrier when reinsulating? I do not see one now unless that is the function of the styrofoam, as well as insulating. —Gary Vernon
P.S. I’m very disappointed in how difficult/impossible it is to get any information from manufacturers!
Holiday Rambler has had several owners over the past many years including Harley-Davidson way back in the late 1980s. As the brand shut down, sat dormant, and then the name got purchased, unfortunately, there was very little documentation that was archived or traveled along with the name. This is typical for companies that close such as National RV, Monaco, and others. 2008-2011 was probably the worst of times, as the industry was at an all-time low and many companies went out of business.
Holiday Rambler walls
If memory serves me correctly, the aluminum exterior walls of your 2006 Holiday Rambler Admiral are fastened with rivets rather than adhesive. Is this correct? And I do believe your interior walls are a thin plywood called Luaun with a wallpaper-type interior skin, right? If so, the panel will be hard to pull apart from the block foam and aluminum framework without tearing either the Luaun or the block foam. Then you will have an issue getting the new paneling fastened. Most renovators either paint the existing walls or apply stick-on wallpaper. I don’t know of any RV manufacturer that used a vapor barrier. However, I think it would be a good idea.
I recommend researching Vintage Camper Trailer magazine. They specialize in renovating vintage units and might be familiar with the HR history. If you do get the interior paneling off, I would suggest replacing any loose-fill insulation with block foam. Most manufacturers use the 2# white beadboard, as the adhesive holds better. Winnebago used the Dow Blue Board for awhile but found the thickness was not consistent and the slick surface caused delamination.
One thing I have witnessed in renovations is fastening the interior paneling to the framework using flat head screws in line. Then they’re covered with a paneling seam tape—which is a decorative tape used to cover seams between two panel edges.
Read more from Dave here.
Dave Solberg is a leading expert in the RV industry and author of the “RV Handbook” as well as the Managing Editor of the RV Repair Club.
HAVE A QUESTION FOR DAVE?
We have started a new forum link for Ask Dave. Please be as brief as possible. Attach a photo or two if it might help Dave with his response. Click to visit Dave’s forum. Or send your inquiries to him using the form below.
1/3 This is a 3 parter
I have a 1972 29′ aluminum box framed HR. It has a gap between the outer aluminum skin the width of the aluminum framing.
Then there is 1 inch thick foam board with luan glued to it. The seams joining each sheet at the sides were somehow joined seamlessly, im not sure by what, some matching tape that isnt ease to tell.
Anyways, Ive also gutted her and designed my own way to do it.
First, I bought ‘rain shield’ a meshed sheet roll of ‘plastic’, like a loose brillow pad, used initially as an air gap behind cedar wall and roof shingles allowing air circulation preventing any rot from moist air.
Now that same product has come a long way. Its now hard and heat proof, used under metal roof and siding for same principle, allowing air circulation to remove moisture from accumulating between cold metal, or hot.. and different underside temp that can cause condensation.
So i bought the 3/8″ stuff for metal roofs.
I next ‘straped’ the aluminum framing with 1x2s ..actually they are 3/4 by 1 5/8. I did thermal break between straping and frame with pink sill gasket used in house construction. I calked it to frame, place straping over this and used as few SS flat screws to secure well, and when half screwed in, put a dab of butyl caulking on threads to draw down into wood to metal furthering thermal break. Now my insulation available depth is 2inches double the R value of foam board.
I used Rock Wool insulation to fill cavoty and into hollow sides of framing, lapping a bit over straping on sides, top. It friction holds in well but to prevent any sagging I overkilled by using spray foam as a ‘glue’ on joining pieces to make it hold fast no matter what.
Now vapour barrier and BLUE TUCK TAPE. red might unglue in cold weather. Blue much improved.
The vapour barrier is important to be well laid in. Tucking behind outlets , switches and taped to wall barrier. Extra allowed to lap on floor and placed vinyl plank and baseboard to hold in well. You could tape.
Now wall board. I 2x primed with an exterior acrylic paint, both sides and raw edges. Used SS air gun nails to attach to straping. I had put a line of calk on plastic before hand to keep vapour integrity though overkill.
Then I used 1/2inch thick straping to create seam covering but rather than every 24 inch, i put every 12 inch to make a board and batten effect. I calked the seam to attach and used SS air gun nails to hold as well. Now Paint!
For cielings, which were done first before walIs, I left in old foamboard under aluminum skin. I did though fill joins/cracks with spray foam and spray foamed (can stuff) empty spaces like around roof vent framing etc. I did Rockwool the same as walls except didnt overlap fave of frame.
I didnt strap. Next I just calked aluminum framing to hold vapour barrier, in 1 long sheet tucking sides into space at top of wall that the foam ceiling panels fit in to. I taped to wall vapour.I then bought 1 inch closed cell 4×8 sheets sandwiched between thin layer of fiberglass. Got at commercial roofing supply and much cheaper than home depot blue board with better R value
Used SS screws to attach at edges and reused plastic flower capped screws in the field of sheet. Last resnap up seam board that was there. I might later face ceiling with luan but painted ceiling 2x and seams solid enough.
So why all the thermal breaking and tight vapour barrier etc? I live in my HR year round. 36°C to -10°C.
I heat, breath, shower cook and AC in her. Condensation rather tjan leaking is the killer.
In humid areas lijely not great either. I have to vent and circulate air well in winter especially through gap in roof vent with vent cover over that oe vents would condensate. Now covers do but drip onto otherwise just barely open roof vent.
I dehumidify 1 day each week and use fans one low and other high at other end of trailer to encourage circulating air and air temps. Thermal breaks also help. Otherwise every interior svrew head would transfer cold from outer skin, through frame to heated inside dripping at each one.
Window frame likewise thermal broke with pink sill foam gasket, then fitted right angle wood trim/frame combined. I also use butterfly clips to clip in thin wood framed and double plastic winter window. Its set inside window frame and has closed cell foam tape around its perimiter. Butterfly clips secure it. I did this as condensation down single pane window has to be addressed too. Put in winter wood/foam door gasket for citting drafts too.
Works excellent!!! Very happy I went the extra mile. But of course… seal your exterior roof seams first
No point going to all this trouble and have roof or window leaks. PS.. i could see in the inside metal skin, dried impression of streaming water.. condensation lines from top of wall but inside not from outside.. makes sense.. heat rises,heat plus humid air plus cold metal… condensation. Wood rot at floir wall junction possible. I lucked out there.
So that mesh air gap between outer skin and rockwool is crucial. The warmth of insulation against cold metal that is porous.. not closed cell no air gaps.. will create condensation layer where they meet.
I dint think spray foam closed cell into walls and ceiling is for RVs. Every step on roof will crack it. Every racking while under tow and levelling trailer will crack walls. A cracked insulation is luke no insulation at all especially if you live in it or cool inside on a hot day or heat on a cold one. Overtime you will have a pond held back in your roof vapour barrier.
Thats what happened to me. Rusting cans in the cupboard. Delaminating cupboard doors. Wall foam/luan bulding in towards heated room and away from moist cold on back side. It sucks. But no more.
6) Don’t glue the insulation to the back of the aluminum skin. The sun heated temperature of the skin will destroy any bond the glue will have (over a short time). The interior skin would be best glued and fastened to the framing. Glue choice will be some kind of ‘caulk tube’ applied material that will be able to be vertical without running and have an ‘open time’ long enough to not ‘skin over’ before you get the wallboard up. I recommend having help to do this so it can be done quickly.
7) Securing the wallboard to the tube frame will need to spread the glue and close the joint. It can be done with either screws or blind rivets. Spacing needs to be pretty close because the thin wallboard will flex a lot This is going to leave a very prominent, visible pattern that there is no practical way to disguise (well). Small (1/8″ or smaller) broad head rivets are likely best (shallowest and broadest heads). Do not use countersunk head rivets as they have an inadequate grip on the luan.
Thank you for all of your very knowledgeable information, Steve! We, and our RVtravel.com readers, appreciate it very much! Have a great day. 😀 –Diane
3) The aluminum skin is probably not part of the glue sandwich so when the insulation is removed, should be clean.
4) 1.5lb EPS is poor insulation having an R-value of ~3/inch. It is far better to use Polyisocyanurate (aka urethane foam faced with foil on both sides which is not very structurally strong) or extruded polystyrene (XPS) with an R-value of ~6.5/inch (which is stronger). For walls, 1.5lb/cuft is adequate. Floors should have 2.5lb/cuft densities.
5) Gluing it back together as it was is impossible since urethane glue (‘Gorilla glue’) is a moisture activated and foams when it cures, requiring the wall to be held in a vacuum clamp.
I’m a former plant engineer for Safari Motor Coaches and built their wall lamination system. SMC walls consist of an aluminum outer skin riveted to 1-1/2″ square tube framing with 1.5lb/cuft density expanded polystyrene foam and interior with pre-papered 1/8″ luan, all glued with urethane glue. We previously used sprayed contact to assemble the walls. It sounds like a similar construction.
1) No vapor barrier is required since the aluminum/fiberglass outer layer is impermeable to water.
2) Wall disassembly (this is an incredibly big job); removing the interior walls, you will find that the luan wallboard and EPS foam are glued in and you will need destroy them in order to remove them. I am assuming this wall is glue-laminated which it almost certainly is or it would not have lasted long. Once the wallboard is removed, the EPS will be torn up. Removing it is not difficult BUT sharp tools that make contact with the outer skin, can transfer scrape marks through the wall.
He has a handful of headaches ahead, wishing him good luck. For a non professional to tackle a job like that he’ll need all the good luck he can get.