Hardi Board for a floor

[Old boat owner]

I need to totally replace the floor in my 19ft fishing boat. Don't want to sink a whole lot of money into it and marine plywood is hard to come by. Has anyone use 1/2" hardi board for the flooring ? It's a concrete material but doesn't seem to weigh much more than the plywood would. It would be 100% waterproof and should last forever. Would it have the strength that the plywood would?

 

[fuzzeywiggler]

Re: Hardi Board for a floor

It sounds like it might work but i have never worked with the stuff before.
Is it brittle? Is it roughly the same weight as plywood?


Fuzzey

o and nothing is 100% waterproof haha

 

[Old boat owner]

Re: Hardi Board for a floor

It cuts just like plywood, except you use a different blade. Weight seems to be about the same. They showed a video clip of a piece that has been in submerged in water for 14 years and is still as solid as it was day one.

 

[fuzzeywiggler]

Re: Hardi Board for a floor

Unless you hear otherwise I would try it and let us know how it goes.

It might be hard to shape to make a new deck though...

Fuzzey

 

[Mark42]

Re: Hardi Board for a floor

I've worked with concrete board and would not put it in a boat. Its heaver than plywood, cracks easy, and is not easy to cut.

Use pressure treated plywood instead.

 

[WizeOne]

Re: Hardi Board for a floor

Use pressure treated plywood instead.

...., resin soaked on all sides and ends and covered with, at least a layer of 10 oz cloth. (IMHO)

Interesting to reflect, after my resto project, the original plywood flooring was covered with a layer of cloth (weight unknown) then covered with a very uneven application of resin (I assume polyester) So on one hand you coud see the loose fibers of the cloth and on the other you could see where it appeared that the resin had been applied with a squeegee or trowel.

When I did my 'deck', I rolled the epoxy on with a roller, layed down the 10 oz cloth then rolled it again with the same roller. It looked evenly filled and very smooth with just a hint of the underlying cloth.

Weight aside, I agree, the Hardi ??? would be more brittle (less flexible) and not have the span strenght of plywood. Additionally, I wonder how resin and glass would adhere to it.

 

[tashasdaddy]

Re: Hardi Board for a floor

i've work with the tile board, and the siding, i do not think it would take the beating. for a deck it would have to be backed, just like a counter top, or bath room floor. if not they would just attach it to the floor joist.

 

[ospreyengineer]

Re: Hardi Board for a floor

I am a structural engineer at the university of north florida. Several friends of mine have built a canoe and a jet solar powered boat out of regular poured concrete. For replacing a floor I am positive that 1/2'' hardi board will work, but i wouldn't use 1/4'' hardi board. The epoxy will bond to this the cloth will adhere to the epoxy and the resin will adhere to the cloth. I will consult with my fellow engineers to make sure my math is right, but I think this is an excellent idea that would revolutionize the way some of the strict old timers using nothing but marine plywood will change their minds once they see how the project turns out. It's a brave new world!!! New techniques and materials are being employed all the time.

 

[chavez]

Re: Hardi Board for a floor

It will be very brittle - little to no tensial strength. You could coat with epoxy and glass, but over time the board would surely crack. Then you would be relying on the glass to provide all the restance.

Travis

 

[Skiuseme]

Re: Hardi Board for a floor

I have used it in my kitchen floor. You must attach it to a sub floor. If you go the the Home depot try an pick one up by its edges. It will break!! It must be supported under all areas if you are going to have any downward force on it. So since you are going to have to put down a subfloor under it you might as well just get the plywood that is ment for the job.

http://www.jameshardie.com/homeowner/backerboard.shtml

Doing thing right the first time has saved a lot of people time and money in the past Im sure this also might be the case in this situation.

 

[i386]

Re: Hardi Board for a floor

Yea it'll break. You don't even have to use a saw. It can be scored it with a razor knife and break it like Sheetrock.

 

[tashasdaddy]

Re: Hardi Board for a floor

they also make siding, even comes in 4 x 8, but it is for vertical installation, very brittle horizonal.

 

[Joe_the_boatman]

Re: Hardi Board for a floor

I am a structural engineer at the university of north florida. Several friends of mine have built a canoe and a jet solar powered boat out of regular poured concrete. For replacing a floor I am positive that 1/2'' hardi board will work, but i wouldn't use 1/4'' hardi board. The epoxy will bond to this the cloth will adhere to the epoxy and the resin will adhere to the cloth. I will consult with my fellow engineers to make sure my math is right, but I think this is an excellent idea that would revolutionize the way some of the strict old timers using nothing but marine plywood will change their minds once they see how the project turns out. It's a brave new world!!! New techniques and materials are being employed all the time.

Bad idea using concrete alone.... tensile strength of plywood ~31 MPa, concrete is ~6 MPa (and that's after 5 years of curing, expect about 75% of that after 30 days cure).

If your buddies are making boats out of the stuff, they're introducing other materials (like glass strands), and then it's a composite, not just "poured concrete". A few decades ago, concrete was popular for boat builders though (research "ferrocement"), but even then, they're reinforced w/ something.

As you said, making a fiberglass/cement composite might work, but why use concrete instead of wood?

Just use pressure treated. There's a reason boats have been made of wood for millenia, and still are today. Excellent strength to weight ratio, fairly inexpensive, and readily available.

references:
http://robots.freehostia.com/Materials/MaterialsBody.html
http://uk.encarta.msn.com/encyclopedia_761558777/concrete.html