looks like it's gonna be awsome.
1993 Dodge W350 Cummins with all the goodies
2014 Ram 1500 Laramie Longhorn 2wd 395hp
2017 Forest River Surveyor 243 RBS
2001 Super Sherpa & 2012 DL650A go along also
Jfet wrote:
Steve, very nice job on your aluminum roof. I am now unsure if I want to go aluminum though. I see you used a vapor barrier under the aluminum (smart) but this would not allow me to sikaflex the aluminum directly to the marine plywood. Perhaps TPO or that other EPDM? stuff would be the better way to go for me, so I can bond it to the plywood that is screwed/glued to the metal roof joists.
Hmmm...
Steve, very nice job on your aluminum roof. I am now unsure if I want to go aluminum though. I see you used a vapor barrier under the aluminum (smart) but this would not allow me to sikaflex the aluminum directly to the marine plywood. Perhaps TPO or that other EPDM? stuff would be the better way to go for me, so I can bond it to the plywood that is screwed/glued to the metal roof joists.
Hmmm...
There would be no need for a vapor barrier between the aluminum and plywood , the aluminum , especially if one sheet , is in effect a vapor barrier . Add to this that is the wrong placement of a vapor barrier which should be on the inside wall ( warm side of insulation ) it becomes a negative . On a TC which usually has an impervious material as an outside skin I question if a vapor barrier should be used at all , even on the inside . Some how the wall has to breath or condensation will be trapped and eventually cause problems . Unless of course you can vacuum seal it or fill it with gas as in thermal windows , but I doubt that is practical .
'68 Avion C-11
'02 GMC DRW D/A flatbed
ticki2 wrote:
There would be no need for a vapor barrier between the aluminum and plywood , the aluminum , especially if one sheet , is in effect a vapor barrier . Add to this that is the wrong placement of a vapor barrier which should be on the inside wall ( warm side of insulation ) it becomes a negative . On a TC which usually has an impervious material as an outside skin I question if a vapor barrier should be used at all , even on the inside . Some how the wall has to breath or condensation will be trapped and eventually cause problems . Unless of course you can vacuum seal it or fill it with gas as in thermal windows , but I doubt that is practical .
There would be no need for a vapor barrier between the aluminum and plywood , the aluminum , especially if one sheet , is in effect a vapor barrier . Add to this that is the wrong placement of a vapor barrier which should be on the inside wall ( warm side of insulation ) it becomes a negative . On a TC which usually has an impervious material as an outside skin I question if a vapor barrier should be used at all , even on the inside . Some how the wall has to breath or condensation will be trapped and eventually cause problems . Unless of course you can vacuum seal it or fill it with gas as in thermal windows , but I doubt that is practical .
ticki2, but then why did he put the vapor barrier right under the aluminum and nobody on the 11 page roof rebuild thread said anything negative about it?
Jfet wrote:
Steve, very nice job on your aluminum roof. I am now unsure if I want to go aluminum though. I see you used a vapor barrier under the aluminum (smart) but this would not allow me to sikaflex the aluminum directly to the marine plywood. Perhaps TPO or that other EPDM? stuff would be the better way to go for me, so I can bond it to the plywood that is screwed/glued to the metal roof joists.
Hmmm...
sabconsulting wrote:
Just to add to bka0721's comments - this is the write-up I did on adding solar panels to my aluminum roof:
Solar clicky...
The first page also contains links to the complete roof rebuild.
Unfortunately I have lots of screws going through my roof, but I didn't have much alternative if I wanted to keep all the hatches etc. that the camper originally had.
Cheers,
Steve.
Just to add to bka0721's comments - this is the write-up I did on adding solar panels to my aluminum roof:
Solar clicky...
The first page also contains links to the complete roof rebuild.
Unfortunately I have lots of screws going through my roof, but I didn't have much alternative if I wanted to keep all the hatches etc. that the camper originally had.
Cheers,
Steve.
Steve, very nice job on your aluminum roof. I am now unsure if I want to go aluminum though. I see you used a vapor barrier under the aluminum (smart) but this would not allow me to sikaflex the aluminum directly to the marine plywood. Perhaps TPO or that other EPDM? stuff would be the better way to go for me, so I can bond it to the plywood that is screwed/glued to the metal roof joists.
Hmmm...
Having not read all this, I'm not sure of the application here, but I would not ordinarily recommend thee sole "vapor barrier under the aluminum". For one thing, the aluminum is a terrific vapor barrier all on it's own.
The most important other aspect, though, is that the aluminum already forms a vapor barrier on the exterior "cold side" where we don't really want it. Because of the need for "wet" water-proofing, it can't be helped, but this aluminum barrier traps any attic cavity humidity from properly dissipating outdoors through the outer membrane. That is to say that any vapor that penetrates the inner ceiling cannot continue to the outside which, in turn, means that it is likely to be trapped and reach the dew point within the wall cavity and therefore condense to "wet" water. Rot and mold can follow.
As an example, a full size stick home has a large hollow "trussed" attic that is ventilated to allow vapor escape, even though the shingles prevent rain intrusion. Some curved camper roofs also have shallow trusses that allow venting, wiring and even A/C ducts to run the length of the RV roof.
It is possible to vent a flat camper ceiling in a similar way by running an additional layer of purlins (cross-timbers) under rafters at a 90 degree angle. After the ceiling panels are attached, air may still freely circulate through the entire matrix by weaving around the perpendicular framing, if that makes sense. A bonus is that wiring may be simply threaded through this same matrix without drilling holes in single layer roof joists. The idea would be to add insulation only between the purlins and allow open ventable air space above this layer. It is important to add a "warm side" vapor barrier between the ceiling panels and bottom of the insulation. This is actually more important on a roof assembly than wall assembly. There is a tendency of more accumulated vapor towards the ceiling.
TRIVIA:
The breathable air inside the cabin is made up of mostly nitrogen and oxygen in that order of prominence. Both these gaseous molecules exist in relatively dense pairs, O2 and N2. Because they exist in pairs they (the denser air) are actually heavier than H2O "gaseous" dry vapor which exists as "feathery" single molecules. H2O is only one "half-heavy" oxygen molecule and two very light hydrogen atoms. Dry water vapor therefore "floats" to the top of the interior atmosphere, just like light wood on heavy water. This also true of outdoors evaporating humidity. Outside the invisible rising vapor eventually reaches a cool upper air that is cold enough to condense the vapor to tiny droplets, combined molecules ("wet" water) we are able to see as clouds (same as fog). If the droplets coagulate too much, they get compact and heavy enough to fall as rain. The point being, water vapor itself, is lighter than air and collects near ceilings.
Wes
...
Days spent camping are not subtracted from one's total.
- 2019 Leprechaun 311FS Class C
- Linda, Wes and Quincy the Standard Brown Poodle
2001 F350 Lariat CC 4WD 7.3 PSD dually, chipped, 4" SS exhaust, 350 hp, Rancho 9000's, front receiver, front & rear Roadmasters
2009 Arctic Fox 990S, storm windows, Cummins/Onan, FastGuns, Torklifts
Jfet wrote:
ticki2, but then why did he put the vapor barrier right under the aluminum and nobody on the 11 page roof rebuild thread said anything negative about it?
ticki2 wrote:
There would be no need for a vapor barrier between the aluminum and plywood , the aluminum , especially if one sheet , is in effect a vapor barrier . Add to this that is the wrong placement of a vapor barrier which should be on the inside wall ( warm side of insulation ) it becomes a negative . On a TC which usually has an impervious material as an outside skin I question if a vapor barrier should be used at all , even on the inside . Some how the wall has to breath or condensation will be trapped and eventually cause problems . Unless of course you can vacuum seal it or fill it with gas as in thermal windows , but I doubt that is practical .
There would be no need for a vapor barrier between the aluminum and plywood , the aluminum , especially if one sheet , is in effect a vapor barrier . Add to this that is the wrong placement of a vapor barrier which should be on the inside wall ( warm side of insulation ) it becomes a negative . On a TC which usually has an impervious material as an outside skin I question if a vapor barrier should be used at all , even on the inside . Some how the wall has to breath or condensation will be trapped and eventually cause problems . Unless of course you can vacuum seal it or fill it with gas as in thermal windows , but I doubt that is practical .
ticki2, but then why did he put the vapor barrier right under the aluminum and nobody on the 11 page roof rebuild thread said anything negative about it?
In that thread he mentions putting the plastic under the aluminum as a precaution against condensation under the aluminum , not exactly a vapor barrier . I humbly submit that Tyvek would have been a better product for that purpose . The same problem of condensation in that situation will exist whether the material is aluminum , steel , glass ,plastic , or rubber . It's a non-porous material trapping moisture . In a S&B building moisture can escape through the exterior of the wall and roof , in an RV it cannot , that is why I question the benefit of an interior vapor barrier in an RV . I don't pretend to be an expert in RV building , or anything else for that matter , just food for thought .
I have used Tyvek under metal roofs for that very reason , the difference in that use is the condensation is not trapped , it rolls down the roof on top of the Tyvek and out the eves . The corrugations also provide ventilation .
My Blue Heaven wrote:
Having had two aluminum RV's, I learned the hard way that aluminum dents from hail or rocks. You might want to consider alternatives.
Having had two aluminum RV's, I learned the hard way that aluminum dents from hail or rocks. You might want to consider alternatives.
x2
EPDM maybe?
free radical wrote:
x2
EPDM maybe?
My Blue Heaven wrote:
Having had two aluminum RV's, I learned the hard way that aluminum dents from hail or rocks. You might want to consider alternatives.
Having had two aluminum RV's, I learned the hard way that aluminum dents from hail or rocks. You might want to consider alternatives.
x2
EPDM maybe?
Was thinking EPDM or TPO as an alternative. Certainly they seem easier to handle/bond to the marine ply than aluminum. Probably cost the same or less.
Or the other alternative is to coat the marine ply in fiberglass...messy though.
Also, take a look at Escape trailers built in Canada. Escape trailers I toured their factory and was impressed with their design and strength. I've always wondered how that could be used in TC's. Bigfoots are somewhat similar in that method of construction.
2000 F350 Lariat LE V10 CC LB 4WD DRW
2005 Eagle Cap 850 Camper
1993 Robalo 2440 twin '07 Merc Optimax 150's
1978 Glasply 28' with twin 310hp V8's
Sparky87k5 wrote:
I'm not making a claim that I know anything about building TC's but I've done my share of boat building and boat mods that have included gel coat applications to storage lockers, boats, cabinets and my utility trailer. If you totally enclose your TC in 3/32" plywood and apply sprayed on gel coating, wouldn't that solve leak issues as it does in a boat? In order to keep a fiberglass or wood boat from condensation buildup we apply a felt cloth like covering over the interior. Although aluminum boats are popular, their condensation issues are somewhat hard to eliminate. Just my $.02 worth.
Also, take a look at Escape trailers built in Canada. Escape trailers I toured their factory and was impressed with their design and strength. I've always wondered how that could be used in TC's. Bigfoots are somewhat similar in that method of construction.
I'm not making a claim that I know anything about building TC's but I've done my share of boat building and boat mods that have included gel coat applications to storage lockers, boats, cabinets and my utility trailer. If you totally enclose your TC in 3/32" plywood and apply sprayed on gel coating, wouldn't that solve leak issues as it does in a boat? In order to keep a fiberglass or wood boat from condensation buildup we apply a felt cloth like covering over the interior. Although aluminum boats are popular, their condensation issues are somewhat hard to eliminate. Just my $.02 worth.
Also, take a look at Escape trailers built in Canada. Escape trailers I toured their factory and was impressed with their design and strength. I've always wondered how that could be used in TC's. Bigfoots are somewhat similar in that method of construction.
Be careful with straight gel coat. It's not actually completely water proof. You need to use epoxy for a true waterproof barrier (likely with fiberglass near seams and holes). Once you do that, I would suggest paint as it's easier to apply.
Tammy & Mike
Ford F250 V10
2021 Gray Wolf
Gemini Catamaran 34'
Full Time spliting time between boat and RV
