Sealant question (But not your normal caulking debate!)

[drodio]

I have an Adrenalin Blast adventure trailer (it's for sale...ish -- not in a rush to sell it, but case you're interested: http://www.expeditionportal.com/for...g-My-Adrenalin-Blast-Trailer-San-Francisco-CA )


The trailer swings open, clamshell style.


The floor has been leaking, which led to wood rot. I just tore out the vinyl flooring and the plywood underneath it to find the culprit. Looks like steel screws that have rusted and were letting water in (when the trailer is closed, this floor becomes the top of the trailer).


So now I'm down to bare aluminum + the steel screws. And I'm trying to figure out how best to seal everything back up.


And since the trailer floor is an aluminum tub, I'm thinking it might be a good idea to use some kind of pour-in sealant or even epoxy to really seal everything in well.


Here are the steps I've thought up so far -- but I'm 100% open to suggestions:


1) I was going to use POR 15 marine clean + metal primer to prime the screws and the aluminum around them, and then POR 15 the screws to stop the rust (these screws are permanently installed and will never need to be removed).


2) Then I was debating using some kind of caulk to caulk the screws where they meet the aluminum, as well as caulk the aluminum joint that runs down the middle of the floor.


3) And then I wanted to literally pour in some kind of sealant or epoxy (or something else entirely?) to a depth of about 2 inches. Something that would harden when it dries. (although it *could* stay semi-soft... we'll be walking on it so it just has to be durable)


4) Then I may or may not put vinyl flooring back down, depending on what I end up using in step #3.


I was thinking about using some kind of roof sealant for step 3. But I really have no idea what would be good. I'd love something that's not *too* heavy, as the roof pivots to become the floor... but the weight will probably be OK.


Anyone have any ideas on the steps above, especially what material to use in step #3?! MUCH appreciated.


Here are some pictures:


Here is the floor from an outside view:

Here's the floor from the inside:

Here's a closeup pic of the steel screws that have been rusting (I've since cleaned up the mess around them):

 

[familyof7]

For what it's worth those look like elevator bolts and you can get replacements at the hardware store.

As far sealant. I work in aviation, and EVERYTHING gets a coat of sealant when it gets put together. Skin to structure, better put a skim coat on it. Rivet or other fastener going into a hole, it's getting some sealant. As far as what type? Well that is the million dollar question. The key here is look at the application, what is its exposure? Any petroleum? Is it just rain water? Salt water at all? All of those thing affect your choice. Now a steel fastener in an aluminum hole is another issue they by themselves corrode each other (galvanic corrosion) hence why we put sealant or epoxy primer on every fastener on an airplane! So if you want to fix it the best possible way and only do it once. I would,if in your shoes, replace the fasteners if possible, use an RTV type product it's doesn't have to be heat rated so an inexpensive formula. These should be available in caulking gun sizes (may have to order online). Also install all replacement fasteners "wet" either with epoxy primer (available in rattle cans) or RTV sealant. Then to add a little piece of mind, replace what was plywood with marine grade for extra protection. This is more $$$ upfront, but you can go the cheap route, but you most likely will have to fix it again down the road and kick yourself for not just putting up a few extra dollars and a little extra time to get it fixed right the first time.

I hope that is helpful, we could go down the rabbit hole of what formula of sealant, but a general purpose RTV or silicone sealant like they use on RV roofing would be a good easy to find option.

 

[steelhd]

It's not cheap but I would use plywood and coat all six sides with clear penetrating epoxy sealant. It won't rot again. Then cover with whatever makes you happy. I personally like marine vinyl. IMO exterior grade ply should be adequate since I believe it uses the same adhesive as marine ply but just has more interior voids. And I would use stainless fasteners to secure the ply to the steel tub. This link explains why the potential for corrosion should be very minimal. http://www.ssina.com/corrosion/galvanic.html

 

[familyof7]

Did you figure out what you are going to do?

 

[ABYSS]

Hello Coming at this from a AVAITION background, if you get the rust removed here is what Id suggest.

For sealing around the screws ad seams use PRC1422B1/2 I will warn you it is very expensive but it what is used to seal flight controls on heavy aircraft and provided you prep the surface properly it will last in your application it will more than likely be a one time correction.

In regards to the plywood Id recommend going to the auto parts store and get yourself a gallon jug of fiberglass resin and paint on a good coat on all sides and let it dry. If you want to get expensive go with Gill Floor it is complete composite.

David