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Discussion Starter · #1 ·
I created a 33" x 20" x 33" tall plywood tub, reinforced metal corners ,on van plywood floor with shower drain. I notched down one side to climb in easy. I thought I could use this for multiple water tub use. hand laundry wash, shower and such.
I thought I should line it with fiberglass to water proof it. But I don't know the process of fiberglass. Can I get advise ? what materials, were to shop materials , how to ?
I was planning on just using a liner but I changed my mind and now think it should be fiber glassed.
Thanks.
 

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2021 3500 extended in Michigan
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Fiberglass resin is available at most any hardware store and comes as a two-part system. You mix the resin and hardener, stir it up then brush it on your project. The open time is fairly short so you have to apply it quickly. The stuff has a pretty aggressive odor too so it's best to do it outside.

You can either apply it directly to the plywood or apply it over fiberglass cloth to strengthen the tub.
 

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2018 136" HR
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i would use epoxy resin instead of polyester resin, epoxy doesn't have those toxic fume(low VOC) and its safer to handle compare to poly resin. Also its have better structure properties too but its a bit more expensive compare to polyester resin. I got mine from surfboard supplies store. You probably want to get the longest curing time resin if working on a large area.
if you end up using polyester resin, get a good respirator with a VOC filter. breathing on the VOC from it no good for your health. Also mix small batch at a time, so it doesn't exothermal in the mixing pot which will shorten your curing time. find a friend who have work with fiberglass helps a lot or watch a lot of youtube on it.
 

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Curious how this goes, I plan on doing something similar and after looking into fiberglass I settled on just building a box and coating it in flex seal. But fiberglass done well would look much nicer.
 

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2018 136" HR
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Also there are two type of polyester resin(epoxy is just one type), laminating resin and sanding resin. laminating resin once cure, it will still remain tacky so you can add additional layer of resin/fiberglass at a later time without sanding. But you will need to use a sanding resin for the finish coat so it cure hard without a tacky surface. You can use sanding resin for all your layers too but in order to get the best bond, you will have to fiberglass everything in one go. Once the sanding resin cure, you will need to sand the surface if you want to add another layer on top of it.
 
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2021 3500 extended in Michigan
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Discussion Starter · #7 ·
Fiberglass resin is available at most any hardware store and comes as a two-part system. You mix the resin and hardener, stir it up then brush it on your project. The open time is fairly short so you have to apply it quickly. The stuff has a pretty aggressive odor too so it's best to do it outside.

You can either apply it directly to the plywood or apply it over fiberglass cloth to strengthen the tub.
Should I line it like a shower build with pieces of panel and seal up corners ?
not positive, I think 45 sq.ft. is equal 33" x 20" x 33" tall.
I think I could build a taper drain floor all such better with fiberglass materials.
Thanks for helping me choose a plan.
 

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Should I line it like a shower build with pieces of panel and seal up corners ?
I assume you're thinking about using FRP (fiberglass reinforced plastic) panels and sealing with a good quality caulk.

That would work if done right, but the caulk may not hold up as well as fiberglass would. Many here, myself included, have used FRP panels for shower walls with good results. The FRP certainly looks nicer than the uncoated fiberglass resin will.

You can apply colored gell coat over the fiberglass resin to dress it up but it's another fairly smelly step.

How you plan to handle the drain may be key to which way you build and seal the tub. The FRP will handle some deflection from a slightly tapered floor but it will crack if stressed too far. Probably best to figure out how you'll seal the drain first and go from there.
 

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2014, 138WB, High Roof, Gas, SW MT
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Hi,
In the "for whatever its worth" department, A good plywood to use for this sort of thing is MDO (Medium Density Overlay Plywood). It is used for chemical tanks, freeway signs and other wet/outdoor environments. Its a good quality plywood with resin impregnated face sheets.
Its not as available as regular plywood, but good lumber yards stock it or can get it. I just bought some recently and it was $92 for a 3/4 inch 4 by 8 sheet double sided (resin face sheets on both sides).

The grey water tank on my van is made from MDO that is just painted with exterior paint - still going strong after 8 years.

If you go with the resin coating, I agree with the others that Epoxy would be a better choice.

Gary
 

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2014, 138WB, High Roof, Gas, SW MT
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How did you seal the MDO corners?
Hi,
The pictures on the toward the last half of this page show how I did the joints on my grey tank to minimize exposure of the edge of the MDO.


I have had some MDO outside at my house exposed to the weather for almost 10 years without any protection, so it holds up pretty well even without any special steps.
 
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