Waterproof Airstream - Impossible?

[bhutch74ly]

I'v spent a lot of time and caulk fixing all of the leaks in my 1974, 25 footer. Still, after a rain I have wet plywood against the rear wall. I believe the water is running down the outer skin, under the trim piece above the bumper storage area, and onto the plywood. I've removed the belly pan and black tank and want to get this leak stopped before I close everything back up. For sure I'm getting rid of as much of the pink fiberglass insulation as possible and replacing it with rigid foam board under the tanks. Fortunately, there's no rot yet because the trailer spent most of its years in Arizona. Now that's it's moved to Louisiana I need to correct this or the floor will rot out fairly quickly. All ideas will be appreciated.

Regarding keeping everything in the trailer as dry as possible. After I get all of the significant leaks fixed, I plan to use fans to ventilate the interior and the area between the plywood and belly pan with as much low humidity air as possible when weather permits. I think it's also important to use flooring that will allow water vapor to move from the plywood to the interior space of the trailer. Leaving cabinets and storage areas open for air movement should also help. I'm sure things will get wet from time to time, but, if I can keep things dry most of the time perhaps the trailer will last outlast the present owner.

[perryg114]

You are wise to have flooring that you can pull up and inspect for leaks. The good thing about an Airstream is that when it leaks the floor rots. When an SOB trailer leaks the whole thing rots and falls apart. Untreated white pine won't last long when it gets wet. SOB trailers in Florida rot so fast you can actually see it happening.

Here are some aluminum composite panels from McMaster-Carr. The 1/2" composite aluminum panels would be the way to go. They are expensive but not crazy. A 2ftx4ft section is $164. I am sure there are cheaper suppliers than McMaster-Carr. Is says .21" deflection with a 100lb load which I can only assume would be in the center of the 4 ft section. No one would put a 4ft span on something like this so that is not bad. It is stiffer than plywood. I am sure you could get bigger sheets of this stuff.

http://www.mcmaster.com/#aluminum-co...panels/=g7c4iz

Perry

[barts]

Our 40 year old trailer had some rot near the front door from leaking window seams, minor problems near the battery box door, water heater and of course rear end separation (rot around the rear shell/frame fasteners) due to the poor design of the rear storage compartment cover. When I fixed the rear end separation, I removed the plate that went under the plywood; we've fixed the leaks in the windows and we epoxied all the floor we could reach (we'll be doing the rest as we rework the rest of the cabinets later on). We painted the epoxied floor with an aluminum polyurethane paint and use rugs. Leaks are now easily seen. We may go to a fancier floor covering later... but I really like being able to see what is going on for now.

We need to think of these trailers as boats, which require on-going maintenance to prevent rot from causing problems. Most wooden boats come to grief from rain - fresh water leaks cause dry rot; salt water leaks don't.


- Bart

[tpi]

I think waterproof Airstream is not going to happen, due to design, quality control, and age deterioration issues.

Since leaks are inevitable (perhaps on any RV), I think Airstream should use a floor with much greater resistance to water damage. The way things stand, even a minor unattended leak in a wet location will rot out area of the floor all too soon.

[barts]

If I were doing a shell off rebuild, I'd replace the existing floor with one laminated from two layers of 3/8" plywood w/ overlapping seams and epoxied on the bottom. I'd cover the edges w/ fiberglass cloth & epoxy and then fasten the floor to the frame with self tapping metal screws sunk into the plywood... and then fill, glass and epoxy the entire floor, tinting it to an acceptable color. Areas where I'd need to cut openings for plumbing, etc, would receive epoxy on the raw wood edges. I'd drill (slightly oversize) holes in the edges for the C channel bolts, and swab them w/ epoxy as well.

Floor coverings would be rugs/mats, etc; one could cover the floor with laminates - but no penetrating fasteners.

This setup would be a LOT more leak resistant than the original design; it would also be easier to spot problems before they snowball. Materials costs would be increased by only epoxy & cloth - fairly minor for this scale of project. Of course, regular attention to potential sources of water intrusion are still needed.

- Bart

[Aerowood]

Originally Posted by bhutch74ly

I'v spent a lot of time and caulk fixing all of the leaks in my 1974, 25 footer. Still, after a rain I have wet plywood against the rear wall. I believe the water is running down the outer skin, under the trim piece above the bumper storage area, and onto the plywood. I've removed the belly pan and black tank and want to get this leak stopped before I close everything back up. For sure I'm getting rid of as much of the pink fiberglass insulation as possible and replacing it with rigid foam board under the tanks. Fortunately, there's no rot yet because the trailer spent most of its years in Arizona. Now that's it's moved to Louisiana I need to correct this or the floor will rot out fairly quickly. All ideas will be appreciated.

Regarding keeping everything in the trailer as dry as possible. After I get all of the significant leaks fixed, I plan to use fans to ventilate the interior and the area between the plywood and belly pan with as much low humidity air as possible when weather permits. I think it's also important to use flooring that will allow water vapor to move from the plywood to the interior space of the trailer. Leaving cabinets and storage areas open for air movement should also help. I'm sure things will get wet from time to time, but, if I can keep things dry most of the time perhaps the trailer will last outlast the present owner.

Another thing to check in that area, is where the rear dome cap rivets to the bottom of the window frame. There are several pop rivets that hold the dome to the frame and should be sealed up. All of the condensation from the rear window will run right through these pop rivets.

[dkottum]

They're (all RV's) gonna leak, and condensation happens.

It will always be our responsibility as owners to minimize conditions that cause it, inspect frequently to find it when it does, and seal or repair as soon as possible.

doug k

[dkottum]

If I could ask airstream to make a special floor for me, it would be the plywood they have with no vinyl floor covering. Instead it would have stiff, low pile carpet (coordinated with interior) in large sections so I can easily lift the carpet and look for leaks, and wipe and dry it when they inevitably occur. The removable carpet would also be easy to clean and a snap to replace.

Carpet that functions like tatami mats, or maybe tatami mats.

doug k

I would also use tatami mats under the mattress if condensation is a problem there.

[perryg114]

That bumper plate is the root of all evil. The only way to get to that area to seal it is to remove the trim (belly band) above the bumper and caulk. I removed the plate and it won't go back. I am still in the process of putting the rear of the trailer back together and I will get rid of the bumper storage if necessary. I think I can make a stand alone box that does not touch the rear of the trailer. Another bad thing about the rear bumper storage compartment is the water that leaks past the cover will end up under the trailer where it can rust the frame.

Perry

Originally Posted by bhutch74ly

I'v spent a lot of time and caulk fixing all of the leaks in my 1974, 25 footer. Still, after a rain I have wet plywood against the rear wall. I believe the water is running down the outer skin, under the trim piece above the bumper storage area, and onto the plywood. I've removed the belly pan and black tank and want to get this leak stopped before I close everything back up. For sure I'm getting rid of as much of the pink fiberglass insulation as possible and replacing it with rigid foam board under the tanks. Fortunately, there's no rot yet because the trailer spent most of its years in Arizona. Now that's it's moved to Louisiana I need to correct this or the floor will rot out fairly quickly. All ideas will be appreciated.

Regarding keeping everything in the trailer as dry as possible. After I get all of the significant leaks fixed, I plan to use fans to ventilate the interior and the area between the plywood and belly pan with as much low humidity air as possible when weather permits. I think it's also important to use flooring that will allow water vapor to move from the plywood to the interior space of the trailer. Leaving cabinets and storage areas open for air movement should also help. I'm sure things will get wet from time to time, but, if I can keep things dry most of the time perhaps the trailer will last outlast the present owner.

[Protagonist]

Originally Posted by bhutch74ly

Now that's it's moved to Louisiana I need to correct this or the floor will rot out fairly quickly. All ideas will be appreciated.

Welcome to Louisiana. After living here more than half my life, I can safely say, this place grows on you. Like a fungus! Unfortunately, I don't know of any cure-all (or prevent-all) fix for wood rot in your trailer in this climate. The ventilation will do as much as anything to help.

Practical example - It's not a trailer, but we had a condensation problem in one of our machinery rooms at one of the navigation locks I deal with; the condensation was so bad there was standing water on the floor all the time (the room had concrete walls, and was partially below water level, so warm air on one side, cold water on the other, instant condensation on the warm side of the wall). We fixed it by adding enough forced-air ventilation to provide six complete air changes an hour, which coincidentally is also the US Coast Guard-required level of ventilation for a boat's engine room, and about the same amount of ventilation needed for a bathroom in a new home if it's built according to code.

Take the total volume of your trailer, in cubic feet. Make it easy on yourself and take maximum height, length, and width rather than trying to compute volumes for the curves. Divide that number by 10. That would be the number of cubic feet per minute (cfm) you will need for your fans. You'll want one inlet fan and one exhaust fan, both the same size. If you can't get the exact cfm you calculated, round up to the next larger size. Also, if the fans will be run less than 18 hours a day, go one size larger as well. With your inlet fan and exhaust fan at opposite ends of the trailer, that should take care of any condensation.

Hint - Mount your exhaust fan at the far end from the door you use most often. That way, when you leave a door open, you don't need the inlet fan on, but would still use the exhaust fan.

Side note - For kitchens, code calls for 15 air changes an hour to get rid of odors, excess heat, and stove combustion byproducts; you may want to add an extra exhaust fan in your kitchen, if you don't already have one— it doesn't need to be big— compute the volume of just your kitchen, and divide that number by 6.67 to get the cfm you need for the kitchen exhaust fan. Since you already have six air exhanges an hour for the whole trailer, you would only need nine more for the kitchen.

If you follow this ventilation recommendation, you'll probably feel a breeze inside your trailer all the time when the fans are running. If you can't feel a breeze on your face, you're not moving enough air to deal with condensation in a high-humidity climate. Fair warning, though, this only works for warm climates; up north in winter if you had this much ventilation you'd be heating the whole outdoors!

[barts]

Originally Posted by perryg114

That bumper plate is the root of all evil. The only way to get to that area to seal it is to remove the trim (belly band) above the bumper and caulk. I removed the plate and it won't go back. I am still in the process of putting the rear of the trailer back together and I will get rid of the bumper storage if necessary. I think I can make a stand alone box that does not touch the rear of the trailer. Another bad thing about the rear bumper storage compartment is the water that leaks past the cover will end up under the trailer where it can rust the frame.

Perry

I removed our bumper plate completely when I fixed the rear end separation; the storage compartment cover is hinged on a piece of aluminum angle that goes from frame to frame just behind the end of the trailer. There's no way for water to end up under the plywood... and there are drainage holes in the bottom to let the water drain out.

- Bart

[bhutch74ly]

Bart, you refer to a bumper plat that was removed. Are you referring to the aluminum sheet metal just forward of the piano hinge for the storage compartment? Did you remove this plate and move it back a little to allow water to drain down past the floor?

Bob

[perryg114]

I think he got rid of the plate that goes up under the rear of the trailer and he attached the hinge that was attached to the plate to a section of aluminum angle. I plan on doing something similar and making a banana wrap between the frame members similar to what is at the front of the trailer. I don't know why AS did not make this simple change decades ago. I think that 90% of floor rot that warrants replacing the floor is caused by this plate.

Perry

[bhutch74ly]

Perry, I agree that this part of the trailer was poorly designed and is an invitation for water intrusion and rotting of the floor. I also think you and Bart are on the right track for correcting the problem. I plan to move the storage compartment and hinge plate back at least 1/2 inch and caulk everything on the rear of the trailer skin to prevent water from contacting the subfloor. In addition, I'm going to construct a new/modified belly pan for the rear 3' (approx.) of the trailer so any water that enters the pan will be isolated from the steel frame of the trailer. My plan is to use steel Z metal (or two pieces of angle iron bolted together) to attach a galvanized sheet metal pan about 1" below the bottom of the main trailer frame. The new pan will easily slide under the trailer from the rear and will be secured in place to the trailer frame by a couple of bolts at the rear. Any water that enters the dropped pan can exit via a few drain holes. Since I will discard the old galvanized holding tank pan and supporting steel that I removed from the trailer, there should be very little if any increase in weight with the new pan. Any rust and corrosion that takes place will be limited to the new belly pan rather than the trailer frame. Another advantage of this is that it will allow quick access to the black and gray tanks as well as drain pipes. No more drilling out pop rivets to work on the plumbing!

[barts]

Originally Posted by bhutch74ly

Bart, you refer to a bumper plat that was removed. Are you referring to the aluminum sheet metal just forward of the piano hinge for the storage compartment? Did you remove this plate and move it back a little to allow water to drain down past the floor?

Bob

Indeed, that's what I meant. I removed the the plate to which the bumper storage compartment lid fastens; it went under the plywood and sat against (just below) the steel angle plate that secured the skin of the trailer to the frame. When rain fell on the the plate, tired caulking hidden under the rear trim belt allowed water to migrate underneath the plywood, and kept the steel angle plate and aluminum bumper plate wet. Corrosion, rust and rot ensued.... most of the fasteners has rusted out on our trailer, and the floor was wet once I'd removed the bathroom. I could tell we had a problem because when I rested on the bumper, I could see the frame move relative to the shell perhaps .050"...

I've replaced the steel angle plate with one I made from stainless steel... the rotted out floor has been replaced, and the bumper plate is no more as I described earlier. I also added another piece of aluminum skin underneath the existing one (about 12" up) since there was a lot of corrosion around the bottom row of rivets that held the skin to the C channel. I also added a close-set row of rivets that fasten the existing skin, new skin and stainless angle plate together. I replaced the #12 bent over bolts that held the plywood down to the rear frame crossmember with 1/4" stainless bolts with locknuts; the 3/8" bolts at the corners of the frame are now stainless as well.

The bumper plate is gone; I riveted the hinges to a piece of 1.5" aluminum angle that I bolted between the frame rails. There's about 3/4" of space between the rear of the trailer and the angle, so water can drain into the bumper storage compartment and then through the drain holes onto the ground.

The only disadvantage I've found so far is that the opening into the storage compartment is smaller than before, so getting the gray water slinky into the compartment is slightly more difficult.

- Bart

[slowmover]

Have de-humidifier . . will travel.

Silver Streak used to install weep vents on the trailer exterior wall to help cut down on condensation. But the late Bob Ashby (bought, renovated and sold over 115 Silver Streak trailers out of the Houston area up until around 2001) recommended they be caulked off. I can generally find all the failed (ancient) window seals on one of these with a big temp swing due to window condensation.

A recent perusal of an RV catalog showed an air-to-air heat exchanger now available for RV's.

.

[bhutch74ly]

Originally Posted by barts

Indeed, that's what I meant. I removed the the plate to which the bumper storage compartment lid fastens; it went under the plywood and sat against (just below) the steel angle plate that secured the skin of the trailer to the frame. When rain fell on the the plate, tired caulking hidden under the rear trim belt allowed water to migrate underneath the plywood, and kept the steel angle plate and aluminum bumper plate wet. Corrosion, rust and rot ensued.... most of the fasteners has rusted out on our trailer, and the floor was wet once I'd removed the bathroom. I could tell we had a problem because when I rested on the bumper, I could see the frame move relative to the shell perhaps .050"...

I've replaced the steel angle plate with one I made from stainless steel... the rotted out floor has been replaced, and the bumper plate is no more as I described earlier. I also added another piece of aluminum skin underneath the existing one (about 12" up) since there was a lot of corrosion around the bottom row of rivets that held the skin to the C channel. I also added a close-set row of rivets that fasten the existing skin, new skin and stainless angle plate together. I replaced the #12 bent over bolts that held the plywood down to the rear frame crossmember with 1/4" stainless bolts with locknuts; the 3/8" bolts at the corners of the frame are now stainless as well.

The bumper plate is gone; I riveted the hinges to a piece of 1.5" aluminum angle that I bolted between the frame rails. There's about 3/4" of space between the rear of the trailer and the angle, so water can drain into the bumper storage compartment and then through the drain holes onto the ground.

The only disadvantage I've found so far is that the opening into the storage compartment is smaller than before, so getting the gray water slinky into the compartment is slightly more difficult.

- Bart

Thanks for the detailed information. This will be very helpful as I move forward with my 74 restoration project. Fortunately, my trailer has very little rust or floor rot at this time so it should be fairly easy to correct this unfortunate design flaw and prevent future rot and frame separation problems. I guess another option would be to move it back to Tucson, Arizona from its new home in Louisiana. It appears that these trailers can leak for years with little or no damage if the rainfall and humidity are low enough - as in the Arizona desert.

As a result of your last paragraph, I'm going to try not to change the size of the storage compartment and access door even if I have to slightly lengthen or otherwise modify the frame horns in the process. Perhaps simply making a U-shaped bracket to attach the Al bumper to the frame would suffice. And this brings up another question. Where is the power supply cord/cable for these trailers supposed to be stored when not in use? The only place I see to store it is in the rear bumper compartment with the slinky pipe. I would prefer to keep it elsewhere for obvious reasons.

Thanks again to you and others for the great information and recommendations.

Bob

[Foiled Again]

Originally Posted by dkottum

If I could ask airstream to make a special floor for me, it would be the plywood they have with no vinyl floor covering. Instead it would have stiff, low pile carpet (coordinated with interior) in large sections so I can easily lift the carpet and look for leaks, and wipe and dry it when they inevitably occur. The removable carpet would also be easy to clean and a snap to replace.

Carpet that functions like tatami mats, or maybe tatami mats.

doug k

I would also use tatami mats under the mattress if condensation is a problem there.

Industrial - especially Airports use a high grade of carpet tile - ruin one - replace it.

[Foiled Again]

Originally Posted by barts

I removed our bumper plate completely when I fixed the rear end separation; the storage compartment cover is hinged on a piece of aluminum angle that goes from frame to frame just behind the end of the trailer. There's no way for water to end up under the plywood... and there are drainage holes in the bottom to let the water drain out.

- Bart

I have a dumb question. How about drilling weep holes in the bumper plate immediately next to the trim piece. Water would drain into the bumper compartment... and since it has weep holes and other openings - it would just drain out.

Paula

[dkottum]

Paula, I have the same question, even a series of 1/2 inch holes drilled all along this plate would seem to relieve the water we see pooling there every time the trailer gets wet.

doug k