It’s very rare to have a spot in a yard that is already perfectly level to install an above-ground swimming pool on. Most are off at least four inches and more.
What about yards that are extremely sloped? How do you install a pool that looks like the side of a hill? And can it even be done?
Since swimming pools must be level, those installed on extremely sloped yards must level out the area where the pool is going. This will mean that one side of the pool will be in the ground a lot while the other side will be completely out of the ground.
FIRST THING FIRST – DETERMINE THE GRADE OF THE POOL SITE
Knowing just how off-level your yard is where you want an above-ground pool is a good first step. It’s impossible to eyeball the grade of an area, so don’t just think you know the answer to this.
“The grade of the yard is the difference in height between the highest point of where the pool is going to the lowest point”
I wrote an article on “How to figure out how much grade your yard has” here. Read this and determine your grade.
Once your grade is determined, then you will know better what needs to be done to level the earth for the pool.
WHAT IS CONSIDERED A LOT OF GRADE IN A YARD FOR INSTALLING AN ABOVE-GROUND POOL
In my opinion, if you measure out where you want your pool(plus one foot all the way around) and the difference in height or “grade” is eighteen inches or more, then you have a lot of grade.
When your pool area has a lot of grade, then you have to think about a couple of things that you wouldn’t have to if your yard was flatter.
TWO THINGS TO CONSIDER IF YOUR YARD HAS A LOT OF GRADE (MORE THAN 18 INCHES) WHEN INSTALLING AN ABOVE-GROUND POOL
1 Backfilling
Since a swimming pool must be level, putting one up on an extremely off-level yard means that you will be leveling out an area of the yard where the pool is going.
This means that one side of the pool will be in the ground some and the other end will be totally out of the ground. The section of the pool that is in the ground (high side) will need to be backfilled or have a retaining wall built.
When you level the area for an above-ground pool that is on extremely uneven ground, you have to level a much bigger area than the size of the pool. This is so you have room to assemble the pool on the side that is in the ground some.
After the pool is done and filled with water, then you will want to put dirt back around the pool at the high side. This is called “backfilling”.
Learn about backfilling a pool here.
2 Erosion
When there is a difference in grade on the earth, then when it rains, the rainwater will hit the ground and travel down the ground due to gravity.
If there is enough water moving on top of the earth and the ground is loose, then the moving water can take the loose dirt with it toward the lower part of the yard. This is called “erosion”.
When an above-ground pool is installed level in a yard with extremely uneven ground, then when it rains hard, the rainwater can travel from the high side along the pool to the low side.
Now, if there is loose dirt next to the pool, then the rainwater can wash it away from the high side of the pool to the low side (erosion). And you don’t want this.
To prevent erosion, a top layer of rocks or something that rainwater cannot move should be applied along the outside of the pool where the wall meets the earth.
IF YOUR GRADE IS BETWEEN TWO AND FOUR FEET (EXTREME)
When the grade goes two feet or greater, then you have to start considering what will happen when you have to change the liner some years down the road.
A metal-walled above-ground pool should never be drained, but when you need to change the liner, this is unavoidable. And when a pool is two feet in the ground or more (even on just one side), then the possibility of a cave-in during the liner changeout is always a possibility.
To prevent this, pools that are in the ground two feet or more should have either very firm earth around the outside of it (hard backfilling earth), re-enforced backfill (concrete sprinkled in), or a retaining wall.
IF YOUR GRADE IS MORE THAN FOUR FEET
Some people live on or next to hillsides. With this, they can have a grade of more than four feet. This is super, duper extreme. The good news is that you can still have an above-ground pool.
You will hear from the internet and people that don’t know any better that you cannot build up when installing an above-ground pool. This is false!!
If you have a grade bigger than four feet in your yard, you will have no choice but to build up the low side. This is no big deal as I do that with almost every install that has a grade of more than six inches.
So, let’s say that your yard has a five-foot grade. If you dug into the earth from the low side, then you would have the earth(ground level) at a higher level than the pool on the high side (not good).
You want to have your pool set higher than the earth around it. This is common sense as you don’t want rainwater to flow directly into the pool.
With a five-foot grade then, you will want to have the height of the pool to sit at least one foot higher than the highest part of the earth around it. To accomplish this, you will build up the low side of where the pool is going.
You can do this by using the earth that is taken out of the high side of the pool site and transferring it to the low side. This will create a level area in your yard that is set higher.
WHEN BUILDING UP THE LOW SIDE OF AN ABOVE-GROUND POOL INSTALL SITE, CREATE A LEDGE THAT GOES OUT AND AWAY FROM THE LOW SIDE
Now, when doing this for a five-foot grade, you may be raising the low side by two feet or more. This is a lot. When you raise the low side of the pool site by this much, you will want to extend a ledge of level earth out beyond where the pool wall is going on the low side.
What I mean here is that you will be extending the level area of the yard where the pool is sitting at the low side of the yard.
As an example, the area to be leveled for a 24’ round (most common size) pool on extremely uneven ground should be about 27’ or 1.5ft bigger all the way about the pool.
When building up the low side of a pool site by 2 feet or more, you will want to level an area going out and away from where the pool is going on the low side of the yard by another four feet or so.
This means your level area will now be an oval space of about 27’ x 31’. This will create a level ledge about five or six feet from where the pool’s wall will be.
You do this to prevent any future erosion.
By doing this, you will be changing the grade of your yard some. This will require that you lay grass or rock or a retaining wall at this new grade made at the backside of the ledge.
If you don’t re-enforce the built-up earth, then you may get erosion if you get a hard or lengthy rain.
WILL SETTING AN ABOVE-GROUND POOL IN THE GROUND ON ONE SIDE VOID THE WARRANTY?
The short answer here is “no” it won’t. As long as the pool is out of the ground on one side, then the manufacturer does not consider this semi-inground.
Above-ground pool manufacturers are aware that most yards aren’t flat, so this is a gray area, but usually doesn’t void the warranty.
NOTE: Whether this voids the pool warranty or not can depend on who you ask. Retailers may tell you that it does and be wrong. The best way to find out is to get someone from the pool maker (Wilbar, Doughboy) on the phone, which may be very hard to do.
DON’T SET THE PUMP AND FILTER ON THE HIGH SIDE OF THE POOL
Above-ground pool pumps are only gravity fed. This means that the level of the pump must be below the water level of the pool.
If you are installing your pool on extremely uneven ground, then placing the pool’s equipment(pump/filter) on the high side may be higher than the pool’s water level.
Personally, I don’t really want to see the filter standing higher than the pool wall (when close to the pool). I also don’t recommend placing the equipment at the lowest point in case there is any temporary flooding from rain.
Placing the pump and filter then somewhere at the mid-level of the yard is ideal.
What kind of out of level tolerance can you have from corner to corner
Most above ground pool install manuals that address this will say that you can be off-level up to one inch.
Is 5/8” too much in 24 feet
Not at all. That wouldn’t be good for an experienced installer, but not bad for a DIY job.
Hi Dan. I bought a 15x24x52” oval liner to replace the same in a pool I installed 14 yeas ago. Filled about 2 feet water overnight, and 1 side of the wall buckled inward from the tension of the liner. I think I just did not have the liner centered well but I am not sure now. I drained it dry and tried to give the “short side” a little more vinyl. I noticed that the long ens of the pool have enough vinyl to run straight down the wall to the foam coving. But at the sides that is not the case. Evened out, the side vinyl is off the all about 4-5” at the bottom. Is this normal and should the vinyl stretch that much without buckling the wall ? Initially, the buckled side was about 10 away at bottom and the opposite side went straight down all the way. Thanks for your advice.
Sorry I posted this in wrong category. Has nothing to do with uneven ground.
Oval liners are notorious for being tight at either the ends or at the straight sides. This is because actual dimensions of oval pools vary quite a bit. If your liner is installed somewhat straight, the bottom seam can still ride up the wall depending on your situation. In the end, you really have no choice but to keep filling and see if the liner stretches enough. And it usually does. NOTE: If your liner is super tight, wait for warm and sunny weather before filling.
Before we start filling our pool, I’m having second thoughts and came across your site.
We thought our contractor leveled our ground last year for the pool, but alas he didn’t and we can’t dig as our internet lines aren’t far enough down. We brought in 2 truckloads of sand and used that to raise the high end and my husband put a wooden ledge border around high side. My worries are now that the weight of the water will push the sand out if we’re on that side of the pool and cause damage.
Don’t worry about that. The pool water weight cannot displace the sand. It can only give downward pressure which will compress any air within the earth/sand. And even if you have something under the sand that causes displacement (like grass left under the sand), the pool can only push downward and not at all affect the sand outside of the pool. Only erosion can do that.
Hi. I’m in need of sage and sound advice. I am attempting to set up a 21’ round pool. After having a friend mark where my level lines would be, I have discovered there is an 18” grade. My friend has convinced me that I can build a retaining wall and fill with small rock and sand to level. Due to family health issues, my friend is no longer available to assist and advise me. At this point, I have most of the retaining wall built. I am starting to second guess how to accomplish filling in the area. If I use rock then sand on the top, will the sand eventually filter down through the rock and leave the pool liner exposed to the rock edges. Any suggestions on how to proceed are greatly appreciated. I have built the retaining wall 24’ for a 21’ pool.
Thank you for your time,
Terisa
I’m not clear on what area you are filling. You don’t fill the area between the pool wall and the retaining wall. At only 18″ deep though, you most likely won’t have an issue when it’s time to change the liner regardless.
My ground leveler person wants to put 2 layers of quarter minus watering and tampering to get a smooth surface. Is this enough? Every thing I read says a 2-4 in base.
I don’t know what “quarter” means in your question. As far as how much base an above ground pool needs, it’s just enough to create a smooth and level bottom. No worry of settling as it’s extremely rare.