Pontoon floor replacement with a twist

[crazybry79]

ere's what I am doing. I am a slip renter in a small marina in Wisconsin. I am building a floating "community" room for the slip renters in the marina. There is no real estate to build something like this on, so I am building this on a pontoon. The pontoon will have an enclosed room on it, built like a small house - 2x4 walls and roof, vinyl siding, rubber roof, vinyl windows, etc. There will be air conditioning in this, so interior humidity will be 50ish percent. This unit will be stored at the dock at all times (dry dock in winter) and will not be driven. The marina is completely protected and will not see waves / wakes.

The pontoon I bought has a rotten floor and needs replacement. What should I use for flooring. This project is done out of my own goodwill, and although I have no problems doing something like this, I do desire to keep the budget as low as possible.

Can I get away with 3/4 plywood? Maybe if I treat the bottom side with a Thompsons or something? I contemplated putting down a plastic moisture barrier before putting the flooring down (between the aluminum and the floor) to keep moisture out, but I think if moisture does get in, the plastic may keep it in.

Thoughts?

 

[smokeonthewater]

Floor should be exterior grade plywood... Minimum would be painted, best would be glassed...

Forget 2x4 house type construction... Build it like an enclosed porch IE sunroom.... House construction would be MUCH too heavy for a pontoon boat.

Super light construction through and through...

 

[shrew]

As a community space, offered as an amenity to a group of renters at a marina, this should be built to code. This project sounds like the reason building codes are enforced by the state to begin with. The very nature of the "Can I get away with...?" question already has me concerned.

 

[crazybry79]

Thanks for your reply.

I am strongly considering treated 3/4 ply.and sealing the bottom several times. Just looking for opinions.

I'm not concerned about weight. We're reducing mass considerably by building the walls @24"o/c, 3/8 sheeting, milk house board in walls ect.

To offset the weight of the structure, I am adding a row of plastic 55 gallon drums inboard of the logs on either side. The barrels themselves, at 33%submerged, will float the same structure @16" o/c, cabinets, appliances, and several passengers.

 

[shrew]

2 x 4 @ 24" OC is not to building code anywhere. How are you building the joists to support the floor? (material, dimensions). What is the size of the footprint of the structure? This is not a vessel you're building, it's a common access structure.

 

[smokeonthewater]

I'm sorry if this hurts your feelings but your entire plan is filled with bad ideas... You aren't worried about weight but you SHOULD be... Adding inboard flotation does nothing to increase stability and in fact may make it worse.... If you are going to build it as a floating house then the enclosed space needs to be much smaller... Ever notice that small floating cabins have huge porches all around?... This is for outboard flotation so that they won't be top heavy.

Building a narrow top heavy structure, adding flotation inboard, and inviting (I assume often drinking) people to congregate is a recipe for disaster.

Also FWIW treated wood eats aluminum.


The only way to do this fairly safely would be to enclose the pontoon boat as absolutely lightly as possible and limit capacity... A table permanently installed in the center with seating around would prevent a group from clustering on one side.

The safer way to do this would be to simply build a deck over one of the slips from dinged pier to finger pier using the same flotation or pilings the rest if the marina uses and build a small light structure there.

 

[Scott Danforth]

I agree.... Bad idea.