Best waterproof sealant for subfloor?

hopper33 · Dec 3, 2024

I am installing a subfloor and floor in my jon boat, and want to waterproof the floor's edges next to the inside hull. 5200? Flex Glue? Any regular waterproofing silicone?

Sanding down to bare metal could be an issue on the inside hull walls just below the new floor, so anything that adheres to paint is ideal.

Thank you for any assistance!

DaleH · Dec 3, 2024

Most silicones having curing agents that can attack tin.

If you're waterproofing the edges of the wood, epoxy on the edges and underneath would last a lifetime! Get the small 1.5 quart standard kit from Mike at Raka Epoxy for only $36.

Note flexible expoxy like West Systems G-Flex 650 would be used to 'weep it' into any seam you are going to eventualy cover over, the kit is only $22 or so, but the tin should be vinegar-washed and primied before coating with G-Flex. Any eposy that shows needs to be over-coated with paint to protect it from UV/dun damage.

https://raka.com/product/standard-epoxy-kits/

hopper33 · Dec 3, 2024

DaleH said:
Most silicones having curing agents that can attack tin.

If you're waterproofing the edges of the wood, epoxy on the edges and underneath would last a lifetime! Get the small 1.5 quart standard kit from Mike at Raka Epoxy for only $36.

Note flexible expoxy like West Systems G-Flex 650 would be used to 'weep it' into any seam you are going to eventualy cover over, the kit is only $22 or so, but the tin should be vinegar-washed and primied before coating with G-Flex. Any eposy that shows needs to be over-coated with paint to protect it from UV/dun damage.

https://raka.com/product/standard-epoxy-kits/

Thank you for the response!

It's all aluminum. Hull is painted, floor is bare. I can get paint off most of the hull, but down where the seal is needed, getting all paint stripped off would be difficult. Does any of this change your response?

Thanks again.

DaleH · Dec 3, 2024

hopper33 said:
Thank you for the response!

It's all aluminum. Hull is painted, floor is bare. I can get paint off most of the hull, but down where the seal is needed, getting all paint stripped off would be difficult. Does any of this change your response?

Thanks again.

No, paint is good, loose paint not ...

My point was BARE tin should be primed before applying any goop/sealer for the best life and adhesion. You have paint, so if you say used G-Flex as further protection for the seams, that'll work. No need to prime if those areas are painted. Look up my name and that G-Flex and there are Tutirials with pictures I posted that show how to "weep" it in using a hair dryer.

airshot · Dec 4, 2024

I use a product called leak stopper on my small boat. It is a clear outdoor sealant used on roofs and trim including aluminum. Flexible and UV resistant. Avaiable at home depot and tractor supply as well as Amazon. Been on my jon boat for almost 10 years and not one leak. Had some cracks in the hull and used the leak stopper to fill the open cracks, still no leaks, no lifting, no peeling. Good stuff...