What to put under an above ground pool during installation

One of the biggest concerns or questions for any above ground pool purchaser is “What should I put underneath the pool liner during installation?” This is a good question and the answers may surprise you. Each pool installation is different, but there are some general guidelines to follow that will ensure that your above ground pool is installed correctly. Using the wrong materials can cause the swimming pool to corrode or rust out prematurely. Follow along as we dispel the myths behind several common materials used under swimming pool liners and help you make the right choice for above ground pool install.

Above Ground Pool Design

The typical vinyl liner above ground pool is actually designed to be installed directly onto the ground without any added protection for the pool liner. This is perfectly acceptable if the ground is prepared in a way that will prevent damage from occurring to the vinyl pool liner. This is the way that it has been done for decades and great results can be obtained. Occasionally you may come across a swimming pool that comes with some sort of ground protection but this may or may not be the optimal material to put under your swimming pool. Lets discuss the pros and cons of each material  typically used.

Natural Earth Bottom

This is the most common surface for a swimming pool installation and certainly the cheapest. Putting your above ground swimming pool directly onto the ground is easy and no additional expense is required. To go this route you must ensure that the ground is free of any rocks, roots, glass or any other debris that could puncture your pool liner. This is done by simply plucking the debris from the earth until you can find no more. Follow this up by smoothing out the surface with rakes or shovels until an acceptable smoothness of the soil is achieved.

Sand Bottom

Sand is probably the most commonly purchased and talked about material for the swimming pool bottom. This is because sand is readily available most anywhere in the country. Secondly, overall it does do an acceptable job if applied sparingly. The downside of sand is the fact the grains do not cling to one another. This causes the surface to be shifty and footprinty.  Sand is debris free and does a good job of making a smooth surface for the pool liner to lay on, but if the sand is more than 2-3 inches thick the bottom becomes soft and footprints will be present. Footprints make for an bumpy pool floor and makes it difficult to vacuum the pool.

Plastic Sheeting And Foam Bottoms

You here a lot about using plastic sheeting as an added layer of protection. Plastic sheeting is the absolute worst material to place under an above ground pool during installation. It does not prevent weed growth and does not control bugs and critters. But the biggest reason to avoid plastic sheeting is the fact it causes a swimming pool to rust out very quickly. Avoid plastic sheeting, foam board, rolls of foam, roofing paper and any other material water cannot pass through. All of these materials and probably a few others are commonly used and all are extremely bad for a swimming pool.Roofing paper is petroleum based and will react with the vinyl causing damage and discoloring.

The reason for this is the swimming pool liner “sweats” or gives off large amounts of condensation. This condensation is wicked up by the earth below allowing the pool walls and frame to dry out. When plastic sheeting is used under the liner, the condensation is trapped and cannot be absorbed by the ground. This keeps the pool wall and frame soaked around the clock and quickly leads to extensive corrosion.

Carpet Under Pool

Sometimes we get asked about using carpet under a swimming pool liner. The answer here is to avoid it too. Carpet holds moisture and will stay soggy further promoting rust. Aside from that, carpet smells bad in these conditions and will rot away. Carpet does not stop nutgrass or critters and has no advantage.

Pool Floor Padding

By far the best material to place under a swimming pool liner is Armor Shield or Gorilla Pad. These materials are breathable allowing moisture to escape and are extremely tough, keeping insects and moles from coming through and piercing the vinyl pool liner. The Armor Shield and Gorilla Pad come pre-cut and sized to make installation easy. Armor Shield pool floor padding and pool cove are both highly recommended even when installing an above ground pool on concrete. I have included a link to another blog that details installation of an above ground pool on concrete surfaces.

Best Recommendations

I may have left out many other materials that someone could use under an above ground pool during installation, but you can decide for yourself what is best for you. A good rule of thumb is to remember that if water cannot pass through it, corrosion will follow. If it is made of petroleum it will react with the vinyl ruining your pool liner. If it has holes in it nutgrass or critters may be able to pass through. I will give my proven way to protect your liner from the issues above. During installation I would follow the procedures below to obtain the best results:

1.) Smooth out the pool bottom the best you can removing all debris. Use a small amount of clean fill dirt or any type sand to make smooth if needed.

2.) Apply a weed killer that specifies it works against Nut Sedge or nut grass. Use as directed. Nut Sedge is the only weed or grass that can grow through a swimming pool liner.

3.) Use a pool floor pad like Armor Shield or Gorilla Pad to get the pool liner up off the ground as well as keep moles, beetles or insects at bay. If your pool is buried deep down into the earth or critters are scarce in your area you may pass on the floor padding, although it is great piece of mind. But the weed killer I would never pass on. I have seen Nut Sedge grow through pool liners even when the pool was recessed 2-3 feet into the ground.

4.) Clear an area all the way around the outside of the pool approximately one foot out from the pool wall. Fill this area with gravel, rocks or wood chips. Spray this area with the weed killer too and maintain a weed and grass free zone at all times. Nutgrass will grow from the outside, go up under the pool wall and through your vinyl liner. Keep this area around the pool inhospitable for bugs and animals.

If your pool is buried deep down into the earth or critters are scarce in your area you may pass on the floor padding, but the weed killer I would never pass on.

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