Having a pond is one of the best ways to enhance the aesthetics of your backyard. Not only does it provide some much needed variation to an otherwise run of the mill garden, but you can also raise fish, plants, and other aquatic organisms which will only add to the beauty.

Sometimes when people need to increase the size of their ponds, they need to join their pond liner with a newer liner. But most people do not know how to join them or if they can even be joined. Some buy a new, larger liner which renders the previous one redundant.

So, allow me to show you how to join two pond liners together and the things you should keep in mind while doing it.

The Easiest Way of Joining Two Pond Liners

Joining two pond liners doesn’t need any special training or skills. You just need to be well prepared and know what you’re doing. I’m sure at the beginning you would be nervous, after all, it’s your precious pond we’re talking about. So I’ll show you how to join two pond liners together in a simple manner:

Things you need to ensure

While joining two pond liners, you must have the following items. They are :

  1. 2 pond liners (preferably  EPDM rubber ones)
  2. Acetone
  3. Primer or activator
  4. Pond sealer Tape
  5. Roller brayer (it’s better if a steel one is used)
  6. 3″ stiff brush
  7. Lap sealant
  8. Safety glass and goggles
  9. Chalk

Also, make sure you know what your pond liners are made of, as liners of different materials require different methods of joining.

Now, let’s see how to join two pond liners together. We will try to cover as many variations as possible so you can get to know them all.

How To Join Two Pond Liners Together

Step by step procedure of joining regular liners

The following are the steps you have to follow if you want to join two regular liners.

  1. Safety always comes first. As you are dealing with chemicals like acetone and primer which are harmful to skin and eye, make sure to wear safety goggles and rubber gloves.
  2. Now take the two pond liners and lay them on a flat surface so that there are no creases or folds, especially along the edges that are about to be joined.
  3. After that, overlap them in such a way that the top liner is overlapping the bottom one by at least 4 to 6 inches. Take chalk and mark the bottom liner along the top liner’s edges.
  4. Draw another line, this time draw it 3 inches further away from the previous line.  This should mean the new line is 7-9 inches from the bottom liner’s edge.
  5. Now, fold back the top liner. Apply acetone on a rag and wipe the places where both liners overlap completely.  Make sure that you wipe both the liners. Take some time for the acetone to dry up.
  6. At this point, take a 3″ stiff brush and brush the primer with it. Brush it in a width of 5″ onto both of the liners where they overlap with each other. Then leave them out for the primer to dry. In warmer weather of 75-85 degrees Fahrenheit, it will take about 10 to 15 minutes to dry. However, in cooler weathers or weathers where there is a greater percentage of humidity, it will take a bit longer
  7. Take the pond sealer tape and roll it onto the bottom liner. Don’t cover the chalk line with it, rather keep it half an inch inside the marking. Make sure not to have any air pockets.  To do so, burnish the liner firmly with a steel roller brayer which will make sure the tape is firmly bonded with the bottom liner.
  8. Now, take the folded top liner and flip it back over the bottom one. Make sure that it completely covers the tape. Now to access the tape, fold one corner of the top liner back.
  9. lowly and carefully peel the backing of the tape. Make a 45-degree angle when doing so. Once you have started peeling, start to place the top liner gradually where the tape backing has been peeled.
  10. It’s time for the roller brayer again. Once you have finished placing the top liner, burnish it over by the roller. Make sure to burnish over the whole overlapping section. Burnish over the edge perpendicularly first and then parallel to it, repeating the process.
  11. Brush the primer over the top liner again, this time covering the second chalk line in a 6” wide band. Give it 10-15 minutes to dry as before.
  12. Now with the backing side down, take the cover tape placing it over the overlapping portion of the two liners. Afterward,  remove the backing slowly at a 45 degree angle as before and use the roller brayer to join both the liners.
  13. Repeat the burnishing process, first perpendicular and then parallel to the edges.

Joining regular liners using a 5″ cover tape


When joining liners with a 5″ cover tape instead of 3″ ones, the steps have to be adjusted slightly to accommodate this change.

  • While laying the liners over each other, make a distinct 6” overlapping area this time.
  • Apply the primer along the overlapping line of both liners. This time, apply it 2 inches further on both the top and bottom liners. Use a 3″ stiff brush for this purpose.
  • Allow the primer to dry for 10-15 minutes.
  • Roll the liners with steel rollers and put dots of lap sealant under the pond liner.
  • Peel the wax release paper while making sure the 5″ tape is not removed from the liner at the bottom. Release the wax release from about six inches of the tape underneath.
  • After you are done releasing the wax paper, flip the liners upside down. Brush the top liner against the bottom one carefully and release the wax paper in the same method.

How to join Firestone PondGuard Liners

Firestone PondGuard Liners can be joined by an installation service that is specifically made for this kind of pond liners. They are not very different from the ones described before with some minor adjustments.

  • Overlap the pond liners, maintain at least 100mm area over each other. Mark the line with a chalk 10mm from the edge of the top pond liner.
  • Apply the primer with a 3″ stiff brush along the 10mm chalk line. Wait for 10-15 minutes for the primer to dry.
  • Roll the bottom liner with a steel roller and apply a small black lap sealant dot. Place the lap sealant on roughly two or three inches of the tape under the bottom liner.
  • Making sure that the seam tape does not move away from the bottom liner, peel the wax release paper slowly.
  • Flip the liners upside down so that the seam can’t be seen.
  • The top liner should be carefully brushed against the bottom liner with your hand.
  • Remove the wax release paper from the bottom liner in a similar fashion as the top one, repeating the similar pattern of removing the wax release until all of it is removed.

The Procedure of Joining 2 Pond Liners Using a Splice Kit

You join 2 pond liners using splice kits following the steps mentioned below :

  • First, take the two pond liners you want to splice with each other and lay them out with a minimum of 7 inches of overlap. Mark the overlapping area with chalk so that you can apply primer and seam tape.
  • Now apply the primer with a 3-inch stiff brush over the area that you have just marked on the bottom sheet. Apply it on the underside of the overlapping area of the top liner as well.
  • Keep the primer applied sheets in the sun for about 10-15 minutes for the primer to completely dry off.
  • Now, take the 3-inch seam tape and apply it on the bottom pond liner in a way that is commonly known as the ‘unroll’ fashion. Make sure there aren’t any wrinkles on the tape as you unroll the tape onto the bottom liner keeping it tout.
  • With the help of a small steel roller, roll the tape you have just applied onto the bottom sheet. Apply a dot of lap sealant onto the bottom sheet a couple of inches away from the seam tape.
  • Start peeling the wax release paper from the tape onto the bottom sheet. Make sure that you start peeling the tape from one end and from around 6 inches. Do it in such a way that the seam tape doesn’t come off the bottom liner and the wax paper isn’t torn off. Now flip the top sheet over the bottom sheet in such a way that the area where the seam tape was applied is completely covered by it. Start peeling the wax paper from the tape at the same time you brush your hand on the top sheet. Continue this motion along the entire seam and completely peel the wax paper off.
  • After you have done all that, finish the top edge with lap sealant.


It is pretty easy to join two pond liners if you take your time and do it properly. Sure, there are a few steps that need to be taken but the results will last for many years. By now, you should have a clear understanding of how to join two pond liners together. Get the proper tools ready and the end result will soon be visible.

It’ll be like putting puzzle pieces together or assembling Ikea furniture! Follow these steps carefully and soon enough your new pond liner installation will be complete.

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