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Thread: Fiberglass inside an old gunite pool

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    Fiberglass inside an old gunite pool

    Greeting friends! I have a unique question, something I have been contemplating for a while, and want to run a possible solution by you good people.
    The situation is that I have an old pool, built in the 50's, which has received two plaster coats. We purchased the house as a fixer, and the pool was full of rainwater for a few years prior to us taking ownership. I replumbed the pool with 4" schedule 40, and have recast a saddle on top of the pool which will give us a perimeter overflow rather than skimmers. While drilling the holes for the returns and feeds in the pool, I noticed that the two layers of plaster are delaminating from the gunite. I used my rotohammer, and have removed most of the plaster coating, all the way down to the gunite in most places. From what I can tell, everything is solid.
    While investigating the various options for recoating the inside of the pool, I began to wonder why I couldn't just use a two-part epoxy resin with cloth to coat the inside of the pool. I'd likely finish it off with a pearlescent black/blue urethane clear coat. It would seem that this would give me a great, lasting finish as well as ultimate water-tightness that I could do myself for about half the cost of a plaster job. Does anyone have any experience with this? In my preliminary investigations, it seems that there is a dichotomy of pools - either fiberglass or gunite, but nothing that combines the two (save gunite pools with epoxy paint).

    Thanks in advance for the knowledge-sharing.

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    JasonLion's Avatar
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    Re: Fiberglass inside an old gunite pool

    It isn't all that common, but there are companies that do this as a service in a few areas. The end result is a fiberglass pool with more "structural support" than is really required. If you are comfortable working with fiberglass that is a great approach.
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    harleysilo's Avatar
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    Re: Fiberglass inside an old gunite pool

    How big is this pool? Pics of the saddle? I can't imagaine laying all that glass! How many layers were you thinking?
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    Re: Fiberglass inside an old gunite pool

    Thanks a million everyone - sound like it is feasible. The pool is 16' x 32', and I'll upload pictures when I have a chance. Right now it is a bit scary, with the form boards still on, etc. Thanks again.

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    Samantha Sabrina's Avatar
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    Re: Fiberglass inside an old gunite pool

    Why really bother with the glass?

    Use a good epoxy primer over the gunite, and then several coats of a top quality Epoxy Paint and that should both seal it and give it a nice looking yet durable finish?

    Some epoxy paints have a clear/gel-coat in them, or you could put a separate clear/gel-coat over the paint, that would make it look really slick and smooth.
    Samantha

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    Re: Fiberglass inside an old gunite pool

    Okay, i guess the glass would have added a few hundred extra dollars, I was thinking that the addition of cloth would add stability and crack resistance, possibly resulting in more of a "trouble free pool".

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    Samantha Sabrina's Avatar
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    Re: Fiberglass inside an old gunite pool

    You're right the glass would add some additional strength, but honestly, the epoxy paint they use like for garage floors and such is some really really tough stuff and since gunite is basically concrete without rock in it, (somewhat weaker then regular concrete), it should be plenty strong enough without the glass, just scrub the gunite really well then prime, and several coats of paint, then maybe a clear/top/gel-coat over that to finish it off, it should be as if not more trouble free as anything else you could do.

    Like I said it should look really smooth and slick, and be very durable.

    I have been in a bunch of garages, and factories where they have used this stuff on the floors, it seals the concrete, and prevents stains, it holds up extremely well to oils, gas, diesel, detergents, acids, car, truck, and forklift traffic for years and years, a lil water won't hurt it, lol.
    Samantha

    In the process of building for a 22' Intex Ultra Frame, (completion date up in the air at this point).
    We could not beat our backyard into submission so we "Buried It".

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    Re: Fiberglass inside an old gunite pool

    What type of fiberglass cloth would you use??? Would you put it down on the first coat of wet epoxy, then paint second coat over that?

    I have a brand new poured concrete pool that has never held water since it was built last August. Earthquake hit, but also are some structural definiciencies. All joints need to be properly sealed for sure (one was definitely leaking); and hairline cracks in the floor need to be sealed. Then a complete coating with something strong yet retaining some flexibility.

    Advice would be appreciated. I'm looking at some very expensive options (that I can't afford!) such as pouring a new floor with proper water stop, or the Natare liner system, or AquaFin (which has been discussed here). I was hoping I could waterproof my pool, secure all joints, etc. by opening the joints and inserting a hydrophobic material (that expands if it gets wet) that would function as a water stop, then coat the pool with a good coating that has some decent elongation (like AquaFin, EcoSmarte Epoxy, etc). But maybe using the fiberglass cloth and a good hi-build epoxy would be a good alternative to the AquaFin.

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    JasonLion's Avatar
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    Re: Fiberglass inside an old gunite pool

    Epoxy paint will last a few years. A good fiberglass job can easily last 20 years.
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    Re: Fiberglass inside an old gunite pool

    I have a good amount of experience working with fiberglass. This isn't something you want to take on. Fiberglass pools are form molded into shape and massive amount of manpower is required. The costs for the epoxy resins are very expensive and you wouldn't want to use the mat you'd want the rolled fabric glass. (The mat cracks really easily)

    It can become a big sticky messy smelly bubbly nightmare. Fiberglass placed on a verticle wall will want to slide down when it's properly wetted with resin, all the bubbles have to be removed and each layer of glass used is a lighter and lighter weight until you put on the final gel coats. Not to mention that cut and sanded fiberglass is a cancer causing agent. All kinds of protective equipment needs to be used, respirators etc etc.

    If you want a good resource its http://www.fiberglast.com.

    Fiberglass pools are placed in a two piece mold, they are filled with glass, cut by an automated machine then filled with resin then evacuated to remove extra resin.

    One other thing I've learned over time is for maintenence replace with the original designed product because conversions can cost twice as much or more.

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    Re: Fiberglass inside an old gunite pool

    Quote Originally Posted by jmborchers
    Fiberglass pools are placed in a two piece mold, they are filled with glass, cut by an automated machine then filled with resin then evacuated to remove extra resin.
    That is the common approach, but by no means the only way it is done. There are a couple of companies here and there building fiberglass pools in place inside existing pools that need updating. I don't know what technique they use, but it certainly isn't the one you describe here.
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    Samantha Sabrina's Avatar
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    Re: Fiberglass inside an old gunite pool

    Another thing with fiberglass is once you get the gel coat on and it all sets up you have to sand the gel coat before you can prime and paint.

    If it were me I would clean and slightly widen the cracks, and then use the epoxy paint, making sure to fill the cracks with it, like I stated earlier, that paint is pretty tough stuff, and as long as it holds up under forklifts, cars, and pickups, it should last a pretty good while in a pool that stays full of water.

    It is slightly elastic, but might crack if you get hit with another earth quake, bit the nice thing about the epoxy paint is fixing a crack is not all that hard.
    Samantha

    In the process of building for a 22' Intex Ultra Frame, (completion date up in the air at this point).
    We could not beat our backyard into submission so we "Buried It".

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    Re: Fiberglass inside an old gunite pool

    The "fabric" or biaxial cloth is for strength and then you would put "mat" or roving over it so you don't see the weave.

    I am with Samantha, I wonder if an epoxy barrier coat like we use on fiberglass boats would not seal it. And then you could paint over it. If you did put some cloth down, it could maybe just be one layer of roving or one of biax wih roving on top. Then lots of sanding and fairing to make it smooth. A rolled on barrier coat topped with epoxy paint would sure be easier though.
    Blaine

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    Samantha Sabrina's Avatar
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    Re: Fiberglass inside an old gunite pool

    Yes, boats and Corvettes are a prime example of how well epoxy paints work, just look at the pounding a boat takes, and how long it holds up.
    Samantha

    In the process of building for a 22' Intex Ultra Frame, (completion date up in the air at this point).
    We could not beat our backyard into submission so we "Buried It".

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    Re: Fiberglass inside an old gunite pool

    If you search "pool paint" on this forum you will find example after example of early failure. Whether it should work or not isn't as important as the anecdotal evidence over the years here that it does not.....at least not very long.

    Is there a member out there who has a painted pool that has lasted more than 3-4 years? Perhaps, but based on what I have read, there are not very many of them.
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    Re: Fiberglass inside an old gunite pool

    "The "fabric" or biaxial cloth is for strength and then you would put "mat" or roving over it so you don't see the weave."

    Most mats aren't compatible with Epoxy resins, they require poly or vinyl ester resin.

    Using 2 oz glass cloth those weaves will completely disappear when properly wetted and gel coated.

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    Re: Fiberglass inside an old gunite pool

    I'm sorry, I used roving when talking about chopped mat fabric above. Roving is the woven fabric.

    Anyway, don't know how much different pool construction is from boats but Tartan/C&C Yachts uses chopped mat fabric between the gelcoat and structural fabric on their epoxy boats. They claim it is necessary to get the gelcoat to adhere. Of course they are likely using prepregs and not hand wetting. Then vacuum bagging, dont know how that could be done on the inside of a pool. They say all of the fabric needs to be done at one time for proper adherence.

    Also there are issues with gelcoating an outside surface instead of it being the first layer on a female mold and covered in fabric and resin. So, I agree, this is sounding less and less like any kind of easy job.
    Blaine

    50' x 22' 27k gal shotcrete freeform, 2hp 2 sp Pentair Whisperflo, Pool Pilot RC-52 SWCG, Pentair TR 100 sand filter, Polaris 280, 2 Pentair Intellibrite LED lights with controller, french gray plaster, Butterfield U-20 "smoke"integral colored salt finish concrete cantilever deck on one side, flagstone coping on the other.

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    Fiberglass inside an old gunite pool

    My cousin used an epoxy on her pool that lasted about 5-6 years but it was very expensive. It started to show some wear last season but they have been holding off due to the cost but
    I don't remember the brand?
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    Re: Fiberglass inside an old gunite pool

    Quote Originally Posted by JasonLion
    Quote Originally Posted by jmborchers
    Fiberglass pools are placed in a two piece mold, they are filled with glass, cut by an automated machine then filled with resin then evacuated to remove extra resin.
    That is the common approach, but by no means the only way it is done. There are a couple of companies here and there building fiberglass pools in place inside existing pools that need updating. I don't know what technique they use, but it certainly isn't the one you describe here.
    Jason, do you have any leads for me to find websites using the fiberglass lining you're referring to? Or search words?

    I'm thinking a fiberglass mesh fabric would add strength, but would like to use something that I could put 2 coats of a good high-build epoxy over. Thanks!

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    JasonLion's Avatar
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    Re: Fiberglass inside an old gunite pool

    Here are a couple: first, second. There are others, those are just two I happened across recently.
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