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Can A Fiberglass Pool Pop Out Of The Ground?

Can A Fiberglass Pool Pop Out Of The Ground?

So you’re considering a fiberglass pool, but the vinyl liner and gunite pool contractors you met with said, “those bath tubs pop out of the ground…you don’t want one of those!” Now, you are left feeling confused and feeling nervous about a fiberglass pool. We’re here to tell you that it’s okay, we understand, take a deep breath and relax.  We have handled this one a few hundred times over the past 20 years! Next to cost, this is the most common question we get when discussing fiberglass pools.

In short, the answer to this question is “Yes,” a fiberglass pool can pop out of the ground! BUUUUT, did that vinyl liner and gunite pool contractor tell you a gunite pool can pop, and even vinyl liners can float and rip right off the walls and floor as well?  Maybe, maybe not, but I would assume…not.  LOL!

Let me help you relate before I break this topic down in depth for you.

I assume you own a house since you are considering an in-ground pool. If your house has a basement, you need a sump pump system, right? If your basement didn’t have a sump pump system, your house would take on thousands of gallons of ground water, damaging the foundation of your house and causing floods in the basement! So, we use sump pump systems to depressurize the water around the foundation of any house. Of course, there are exceptions, like if you live on a large hill where water just flows past the house and no sump is required, but for the sake of what we are discussing today, no large hill!

The solution to the groundwater problem isn’t some crazy fix, it simply comes down to making sure you can install some sort of de-watering system for your swimming pool! Today, I am going to lay out for you how a swimming pool can pop out of the ground, the best way to prevent this, and finally, why a fiberglass pool will never pop out of the ground when properly installed and maintained!

Hydro-static pressure around a swimming pool and ground water?

It may have come as a surprise to read that a fiberglass pool can in fact pop out of the ground, but I hope after my comparison to the house, you understand this is totally preventable!  These issues all arise from the same reason – a pesky little thing called hydro static pressure from ground water!

Ground water is considered to be any amount of water that is, well, in the ground! In our case, it happens to be around the fiberglass, concrete, or vinyl liner pool.  Here in Northwest Indiana, we do happen to see it a lot.  Ground water comes from many things such as rains or melted snow, in particular in the springtime or you may just have a high water table underground! So the goal is to eliminate it from being around the pool. Keeping ground water low, you can prevent hydrostatic pressure from popping the pool.

What The Heck Is Hydrostatic Pressure?

Well, if you google it you will get a crazy definition about “fluid and pressure and the force of gravity”….Luke Sky Walker uses the force, right?!”

Let me describe it in a “non-scientific” way…It is the amount of force, (pressure) that “still” water applies to the structure or foundation of an item. (The water must be resting in one area hence “still”).

  • For a pool, it is the amount of pressure the water sitting around the pool undeground applies to the pool walls and floor!
  • For a house it’s the amount of pressure that the water sitting around the foundation applies.

Now, add “buoyant pressure” (upward force) and a pool can pop out of the ground or a vinyl liner will float!

How to Prevent Your Pool from Popping Out of the Ground?

I am not only going to cover how to keep a fiberglass pool from lifting out of the ground, I’m going to go one step further and cover vinyl and gunite pools as well!

Maintain Proper Water Level

  1. Well, to start, the good news for gunite and fiberglass pools is, if you keep the water above the lower portion of the skimmer, you stand a good chance of not ruining the pool. This isn’t the case for a vinyl liner unfortunately, a liner will float since it is not attached to anything and takes significantly less hydro static pressure to float a liner.

De-watering System 

  1. You need to make sure your swimming pool contractor installs a “de-watering system!” If you are getting a fiberglass pool or a vinyl liner pool. A de-watering system is similar to that of a sump pump in your house. Where a sump pump’s job is to pump excess water out and away from your house, so that your basement and crawlspace stay dry and your foundation doesn’t get damaged. A de-watering for your pool allows you to drop a pump and remove any ground water that is around your swimming pool, alleviating the hydrostatic pressure, lessening the chances of damage to your swimming pool and preventing it from popping out of the ground.

A de-watering system is NOT common on a vinyl liner swimming pool! We can tell you from experience it will help greatly! All though, due to the construction of a vinyl liner pool you can not install the pit as deep as a fiberglass pool. With a vinyl liner pool, the dry de-waterting pit will only go down as deep as the shallow end without additional excavation. You will still relieve enough of the pressure and not float the liner.

Proper Backfill

  1. Once you install the pit for the de watering system you also need to make sure the pool is back filled with clean ¾” stone. This allows the ground water to flow through it easier than say sand or crushed lime. Allowing the pump in the pit to remove water as quickly as possible!

Hydro static Valve

  1. A hydro static valve is a PVC fitting that can get plumbed in any type of swimming pool in the main drains or in a low wall drain to relieve pressure. This is most popular with gunite/concrete pools but can also be used in a fiberglass application.

Pool Deck Drainage and Popper Down Spout Locations

  1. All right, we know this one sounds a little strange but we have seen concrete decks that do no have proper drainage, opened deck cracks, or a deck drain that isn’t draining into the yard properly, force rain water from even the most basic of rains get under a pool and eventually cause damage.

Please be sure to make sure your concrete is pitched correctly at the install of your pool. In addition, if the pool is older and the concrete begins to fall like and old “toe stubbing” sidewalk, (hate those!) be sure to hire a concrete restoration company to come lift it back into proper place to avoid improper drainage. If you have large cracks that have opened up this is also something that you should have a concrete restoration company come out to seal up.

Down spouts from gutters are something most pool contractors don’t think of at all! It is important to run all down spouts out with PVC drain tile to the swales of your yard to prevent any water drainage to close to the pool.

Lastly, when deck drains are installed, be along with the downs spouts that they are ran into the swales of your yard as well!

How to assure that your fiberglass pool will not pop out of the ground

If you can follow the steps above and get assurance that your pool contractor is going to execute them all properly, you are already in great shape! To be honest, there is only one true way that we can make sure a fiberglass pool is not popping out of the ground at all! Through the revolutionary pool innovations over at Thursday Pools they have created what they call the FPA, the Fiberglass Pool Anchoring system!

Here is what Thursday Pools has to say about it

“The Geo-Anchor Pool Wall prevents wall movement or bulging. The specially formulated geo-textile material is infused into the pool wall during manufacturing, then rolled up and secured for delivery. During installation, it’s rolled out into the backfill and covered, thus anchoring it to the earth. The extension of this material allows the backfill to grip the pool wall to the earth. By anchoring the walls to the earth, the walls of the fiberglass pool will resist movement or bulge providing the strongest fiberglass pool construction available on the market today.”

Thursday also adds in a hydro static valve and presto! NO POPPING OUT!

Guys, the fear is real! I get it, the process of educating yourself on a fiberglass pool or any swimming pool is strenuous with the little amounts of info on the internet. YES, fiberglass pools can pop out of the ground, but now you know ALL pools can pop or float when not installed properly. Be sure to choose the right swimming pool contractor that knows all of the techniques above and be sure they don’t short-change you and potentially ruin your backyard paradise!