How To Make Above Ground Pool Deeper – A Safe Guide To Expanding
Most above-ground pool owners eventually realize that a standard 48-inch depth is great for wading but a bit shallow for a true swimming experience. If you find yourself wishing for more vertical room to move, you are not alone in wanting a more versatile backyard oasis.
I understand the frustration of feeling restricted by a shallow pool floor, especially when you want to enjoy a refreshing soak or teach the kids to dive for rings. In this guide, I will show you the exact methods used by experts to safely increase your pool’s depth without compromising its structural integrity.
We will explore the “dish” method, the use of expandable liners, and the critical site preparations needed to ensure your project is a success. By the end of this article, you will know exactly how to make above ground pool deeper while keeping your backyard safe and your warranty intact.
Table of Contents
Understanding the Structural Limits of Your Above Ground Pool
Before you grab a shovel, it is vital to understand that an above-ground pool is a carefully balanced piece of engineering. The steel or resin walls are designed to hold the weight of water at a specific height and pressure level.
You cannot simply add more height to the walls of an existing pool, as the frame is not built to withstand the increased lateral pressure. Instead, the process of learning how to make above ground pool deeper focuses on what happens below the bottom rail of the pool frame.
Most manufacturers allow for a “dished” bottom, where the center of the pool is excavated deeper than the perimeter. This method maintains the stability of the wall while providing a deeper “swimming hole” in the middle of the structure.
The Role of the Pool Frame and Track
The bottom track of your pool must always remain on level, undisturbed ground to prevent the walls from buckling or shifting. Any excavation for depth must happen at least 6 to 12 inches away from the inside of the pool wall.
This creates a “shelf” that supports the weight of the wall and the pool’s uprights, ensuring the structure remains square and true. If you undermine this shelf, you risk a catastrophic wall failure that could flood your property and ruin the equipment.
Safety First: Checking Your Local Codes
Before beginning any excavation, check with your local building department regarding pool depths and safety regulations. Some municipalities have specific rules about “deep ends” in above-ground pools, including requirements for ladders and safety ropes.
Always call your local utility marking service to ensure there are no buried power lines or water pipes beneath your pool site. Safety is the most important part of any homesteading or DIY project, and taking these precautionary steps will save you from major headaches later.
how to make above ground pool deeper Using Expandable Liners
The most effective and common way to achieve extra depth is by using an expandable liner. Unlike a standard “overlap” or “beaded” liner, an expandable liner is manufactured with extra material designed to stretch into a recessed area.
When considering how to make above ground pool deeper, the most common DIY approach involves creating a “cove” or a “dish” in the center of the pool floor. A standard liner will usually tear or pull away from the walls if you try to stretch it more than an inch or two.
An expandable liner, however, can typically accommodate a center depth that is 12 to 14 inches deeper than the pool walls. This means a 52-inch pool can effectively become a 64-inch pool in the center, providing a much better experience for taller swimmers.
How Expandable Liners Differ from Standard Liners
Standard liners are cut to fit the exact dimensions of a flat-bottom pool, meaning there is very little “give” in the vinyl. If you excavate a hole and use a standard liner, the pressure of the water will pull the liner tight like a drum, eventually causing a seam failure.
Expandable liners are specifically engineered with a higher elasticity and extra square footage of vinyl in the floor section. This allows the material to sit flush against the newly excavated contours of your pool floor without excessive tension on the seams.
Choosing the Right Liner Material
When upgrading your depth, I recommend choosing a high-gauge vinyl, usually 25 or 30 mil, to handle the extra movement. Thicker liners offer better puncture resistance and are more forgiving during the installation process when you are smoothing out wrinkles in the deep area.
The “Dish” Method: Excavating for Extra Depth
The “dish” method is the industry standard for adding depth to an above-ground pool. This process involves digging out the center of the pool area while leaving a flat perimeter for the pool walls to sit on.
You should aim for a gradual slope from the perimeter toward the center of the pool to ensure the liner sits correctly. A gentle transition prevents the liner from folding or creating dangerous “dead zones” where debris and algae can collect.
It is important to remember that you are not digging out the entire footprint of the pool. You are creating a bowl shape that starts roughly 12 to 18 inches away from the wall’s edge to maintain soil stability near the frame.
Step-by-Step Excavation Process
- Drain and Remove: Completely drain the pool and remove the old liner and any existing floor padding.
- Mark the Perimeter: Measure 18 inches inward from the bottom track and mark a circle with spray paint or chalk.
- Start Digging: Dig out the soil within the marked circle, aiming for a depth of 6 to 12 inches at the deepest point.
- Smooth the Slope: Use a flat shovel or a rake to create a smooth, consistent slope from the 18-inch mark down to the center.
- Check for Rocks: Remove any sharp stones, roots, or debris that could puncture the new liner once the water pressure is applied.
Managing Soil and Drainage
If you have sandy soil, the excavation process is relatively easy, but you must be careful about the slope collapsing. In heavy clay soil, the digging is harder, but the shape will hold much better during the installation process.
Ensure that the bottom of your “dish” does not sit below the local water table, as this can cause the liner to “float” or create mud pockets. If you encounter groundwater, you may need to install a simple drainage system or limit your depth to stay above the moisture level.
Essential Tools and Materials for Pool Expansion
To successfully execute this project, you will need more than just a standard shovel. Having the right tools on hand will make the job faster and ensure a professional-grade finish that lasts for years.
I always suggest keeping a transit level or a long carpenter’s level on a straight board nearby. This allows you to verify that your perimeter remains perfectly flat while you are busy digging out the center section.
You will also need a significant amount of masonry sand or a specialized pool base material. This acts as the final layer between the raw earth and your liner, providing a soft, protective cushion for your feet and the vinyl.
The Equipment List
- Expandable Pool Liner: Sized specifically for your pool’s diameter.
- Masonry Sand: Usually 2 to 3 tons depending on the pool size and depth.
- Pool Coving: Foam or sand wedges that protect the liner at the wall base.
- Plate Compactor: Useful for firming up the soil after excavation.
- Industrial Vacuum: Used to “set” the liner by removing air before filling.
Using Pool Coving Correctly
Coving is a vital component when you are increasing depth because it prevents the liner from being forced under the bottom rail. Whether you use pre-made foam coving or a sand cove, it should be about 6 inches high and 6 inches wide.
This creates a smooth transition from the flat shelf where the wall sits to the start of your downward slope. Without proper coving, the weight of the water in the deeper center can pull the liner out from under the wall, leading to a total pool collapse.
Installing the New Liner for Maximum Depth
Once your excavation is complete and your sand base is smoothed out, it is time to install the expandable liner. This is the most critical phase of learning how to make above ground pool deeper because mistakes here lead to permanent wrinkles.
The best time to install a liner is on a warm, sunny day with temperatures at least 70 degrees Fahrenheit. The sun warms the vinyl, making it much more pliable and stretchy, which is essential for reaching the bottom of your new “dish.”
Start by draping the liner over the walls and securing it loosely. Do not try to pull it tight immediately; let the weight of the water do the work of stretching the material into the deeper center area as you fill the pool slowly.
The Vacuum Method for a Smooth Finish
To get a professional look, insert a shop vacuum hose through the return line hole or over the side of the wall behind the liner. Seal the area around the hose with duct tape and turn the vacuum on to pull the liner tight against the walls and floor.
This removes all the air pockets and allows you to see exactly where wrinkles might form. While the vacuum is running, you can gently shift the liner or push out small folds with your feet before you start adding water.
Filling and Monitoring
As the water level rises, keep an eye on the tension of the liner. If it looks like it is pulling too hard on the top of the wall, you may need to release some of the “overhang” to give it more slack. The goal is to have the liner sit completely flat against the sand base before the water gets too heavy to move it.
Semi-Inground Installation: An Alternative Approach
If you haven’t bought your pool yet, or if you are doing a total rebuild, consider a semi-inground installation. This involves burying the pool 12 to 24 inches into the ground, which naturally provides a deeper feel relative to the surrounding deck or yard.
This method doesn’t necessarily change the internal depth of the pool, but it allows you to use a taller pool wall (like 54 inches) without the pool looking like a massive monolith in your backyard. It also makes it easier to build a deck that sits flush with the top rail.
Note that not all above-ground pools are rated for burial. You must ensure your pool kit is specifically designed with corrosion-resistant coatings or thicker walls meant to withstand the external pressure of the soil.
Pros and Cons of Semi-Inground Pools
The main benefit is the aesthetic appeal and the ease of access for swimmers. However, the downside is the increased cost of excavation and the need for specialized drainage to prevent water from pooling against the buried steel walls.
If you choose this route, always backfill the area around the pool with crushed stone or gravel. This ensures that rainwater drains away from the structure, preventing the soil from becoming heavy and “squeezing” the pool walls inward when the pool is empty.
Common Mistakes to Avoid When Adding Depth
One of the biggest mistakes DIYers make is digging too close to the pool uprights. The uprights provide the vertical support for the entire frame; if the ground beneath them shifts because of nearby excavation, the wall will buckle under pressure.
Another frequent error is using a standard liner for a deep-center pool. While it might look okay for the first few days, the vinyl is under constant stress. Eventually, the seams will fail, usually during the hottest part of the summer when you want the pool the most.
Finally, never leave the pool empty for long periods after excavating. Without the weight of the water to hold the liner and soil in place, the walls of your “dish” can collapse, or the wind can get behind the liner and ruin your hard work.
Maintaining Your Deeper Pool
A deeper center means you will need a slightly more powerful pool vacuum or a robotic cleaner designed for inclines. Debris will naturally gravitate toward the deepest point of the pool, so regular maintenance is key to keeping the water clear.
You should also adjust your chemical calculations. A deeper pool holds more water than a standard flat-bottom pool of the same diameter. Make sure to calculate your new gallonage accurately so you can maintain the proper chlorine and pH levels for safe swimming.
Frequently Asked Questions About Deepening Above Ground Pools
Can I make my pool deeper without replacing the liner?
No, it is nearly impossible to safely deepen an existing pool without removing the old liner. A standard liner does not have the extra material required to stretch into a deeper area, and attempting to do so will result in immediate tearing or structural failure.
How much deeper can I safely go?
Most experts recommend adding no more than 12 inches of depth to the center of an above-ground pool. This ensures that the slope remains gradual enough for the liner to fit and that the structural integrity of the wall shelf is maintained.
Is a deep end safe for children in an above-ground pool?
A “dished” center can be safe, but it requires closer supervision. Because the floor slopes away from the edges, children who are not strong swimmers may find themselves in deeper water unexpectedly. Always use a safety rope to mark the transition to the deeper area.
Will deepening my pool void the warranty?
In many cases, yes. Most manufacturers design their pools for flat-bottom installation. Unless you purchase a pool specifically rated for an expandable liner or a “deep end,” you should assume that excavating the floor will void the warranty on the pool frame and wall.
Final Thoughts on Enhancing Your Pool Depth
Transforming your backyard pool into a deeper, more functional swimming space is a rewarding project that can significantly improve your summer experience. By using an expandable liner and the “dish” excavation method, you can gain that extra foot of depth that makes all the difference for adults and teenagers.
Remember to prioritize the stability of the pool’s perimeter and never compromise the flat shelf that supports the frame. With careful planning, the right tools, and a bit of manual labor, you can create a custom swimming environment that feels luxurious and spacious.
Take your time with the excavation, ensure your sand base is perfectly smooth, and wait for a sunny day to install your new liner. Stay safe, follow the steps carefully, and enjoy your newly deepened backyard retreat!
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