There are many online forums suggesting a variety of sealants for Airstream trailers and everyone seems to have a favourite for certain applications. I decided to try them all out and some others too that I had not heard mentioned before. Here’s what I discovered…
Trempro 635
Probably the best general purpose sealant for any application with Airstreams. This sealant is very easy to apply smoothly with your finger for visible seals and comes in grey so it will blend in well. It adheres perfectly to aluminum, withstands all kinds of weather for external applications, has flexibility, does not crack and can be used on the inside or outside. You can also use it to seal windows or replace gaskets that are no longer available. It keeps well if you do not finish an entire tube at once.
It is not as easy to find as some of the other sealants. Big box hardware stores like Home Depot do not carry it and more specialized stores like Fastenal have to order it in which can take a few days. It is also a little more expensive than some of the others, costing about $12CDN per tube.
Sika Construction Sealant
This is very similar to Trempro 635. Its appearance and feel is almost identical. It might even work a little better on roof applications because it seems to completely withstand the sun. Has great flex, dries well, costs about half the price as Trempro and can be purchased at Home Depot without needing to order. Unlike Trempro, this product pretty much needs to be used all at once as it hardens overnight no matter how you plug it up. I did not use it on any interior applications, though you probably could. Many people have written about a product called Sikaflex which I did not find anywhere, however this Sika construction sealant must be pretty close.
Parbond
This sealant is more runny than the polyurethane-like ones above, therefore it will seep into small crevices nicely that otherwise might not be accessible to a nozzle. It is not useful for indoor applications and its fumes are very strong. The big draw with this one is that the colour matches aluminum almost perfectly. It is a very sparkly, metallic colour that you wont even notice and it is very easy to apply right out of the tube in a straight, neat line. You will not need to flatten it out with your fingers so its not very messy either. Unfortunately, over time it does peel and crumble in the elements. It will need to be re-applied every so often. It costs about $10CDN and needs to be specially ordered.
Brush On Seam Sealer
This product is great for sealing around the aluminum channel and your plywood subfloor and any interior rivets, bolts or screws. They say it is brush on but its quite thick for that so I just used a rubber glove and applied with my hand. It dries a little firmer than Trempro or Sikaflex but still allows a bit of flex. It is airtight, that is for sure. It can be purchased off the shelf at Napa Auto Parts for $45CDN per quart.
Varathane Bar and Table Finish
This is a two part epoxy resin/hardener mixture. It is not useful on aluminum but it is great to put a layer a couple inches out from the aluminum channel on the plywood floor. This will protect against any moisture that may accumulate below the visible floor. It dries very hard, although it always looks wet and transparent. It dries flat so you do not have to worry about an uneven floor. You can pour it or apply it with a brush easily, but the brush will not be useable again. As long as you keep the two mixtures separate you can use it for a long time but as soon as they are mixed you must apply it and whatever you don’t use will become rock hard. This stuff is quite expensive but will last a long time and you will find other interesting uses for it too on other projects.
Leak Seal
This product works surprisingly well for small applications. I sprayed some on a few rivets inside to test it out and under the aluminum channel that keeps the shell fastened to the plywood. It sprays just like spray paint but after two coats it dries with a very thick rubbery texture. I would not suggest using it for exterior application. Available at many stores and is about $12CDN per can.
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Acryl-R
This is a product that is common to Airstream threads. I purchased some and was quite disappointed. You need a special applicator to use it and it is for external use but it did a much poorer job than the Trempro or Sika sealants. Its difficult to apply, is too hard to work with and you should wear some type of ventilator as these fumes are intense.
Below is a photo of a vent that I installed. It has Trempro 635 around it covering all the rivets. The dark colour in the panel next to the vent is the Napa Brush-on Seam Sealer and the dark area on the plywood is the epoxy resin.
A few more photos below of the rivets and aluminum channel being sealed up.
Once all sealants are dry, give your Airstream a good test in a major rain storm or with a hose to check for any leaks you may have missed. Seals around the windows are often overlooked but a common place for leaks.