Swimming Pool Blog
by Mark Garcia April 17, 2019
Inground Pool Liner Replacement Guide
The 80/20 Rule applies - about 80% of inground pool liners are installed in the spring, but only 20% of people do it themselves. If your liner looks tired or torn, then you may consider replacing it yourself.
The cost savings are significant. Inground pool liner replacements can easily run $4000 if priced through a local company, who typically doubles their liner cost and then charges $1500-$2000 in 'labor' costs.
Replacing an inground liner is more involved and more difficult than an aboveground liner, but it is something that a couple of motivated homeowners can do themselves, in a single weekend.
Without further ado, here is my complete guide to in-ground pool liner replacement, and the pitfalls to avoid.
Measuring your Pool
Accurate measurements are key to getting a liner that fits like a glove. Most inground vinyl pools have a geometric floor shape, with precise angles. The corners of the pool, at the top of the wall, have a specific radius measurement. And, most pools have square measures - with both ends and both sides being the exact same length.
However! Many pools are built just slightly askew, and end-up a few inches off from spec.To be sure that you order a correctly fitting liner, measure your pool correctly, and double check your measurements.
You may have measures available from a previous liner order, or you can probably dig up the original spec sheet which shows the length, width, depth and radius of the corners. However! Most pools will vary from the original specs, and can slightly shift over a period of many years, so it's always recommended to remeasure the pool, completely.
Measurement Equipment: You will need a 50 ft measuring tape, rigid or flexible, and a 25 ft rigid tape. A pool pole is used as a vertical rod to measure distances across the floor. A clip board and pencil to write down the pool measurements. Two people are needed to measure the pool, and you don't need to drain the pool, but the water should be clean, so you can see the bottom clearly.
Measurement Form: You will need a measurement form for an inground pool liner. These are fairly standard, but it's best to use the form provided by the dealer that you plan to order the liner from.
Follow the steps of the measurement form, and be sure to fill out all boxes and answer all questions. Don't forget your name and contact information!
To measure depth of shallow end (D), just use a rigid measuring tape, being careful to measure from the bead or track, to the flat floor. For the deep end depth (C), run a tight string (or flexible measuring tape) across the deep end, on the edge of the hopper and use a pool pole, or other long pole, placed into the corner of the hopper. Measure the pole at the point where it intersects the string, and then subtract the distance from the deck to the liner track, or bead. You can also use two pool poles at 90 deg angles to each other, to help hold the vertical pole in position, on larger pools. Holding the pole with a carpenter's level as shown here, is not usually attainable, as (V) is normally at least 4 ft. wide.
To measure length of the pool (E, F, G, H), with water still in the pool, tightly secure a flexible measuring tape (the reel-up type), the length of the pool, then use vertical pool poles to measure the length of each section. Your helper should eyeball the pole to make sure it looks vertical, and is not tilted. When measuring the slope from shallow to deep (F), do not measure down the slope, but measure horizontally to a pole held vertically. You can also use a plumb bob on a horizontal pole, and measure to the vertical string. Once you know 3 of the 4 measures, you can extrapolate the fourth, as long as (E+F+G+H = A).
To measure width of the pool (I, J, K), use a pool pole held vertically in the corner of the hopper, and measure horizontally from the liner track to the pole. Do not measure down the side-slope, the measuring tape should be horizontal. Switch sides and measure the width of the opposite side wall. You can then extrapolate the width of the hopper, as long as (I+J+K = B). Typically, the K and I measures are the same, but don't assume, they can be different.
Measuring Pitfalls to Avoid:
- When measuring F, H, I and K - don't measure down the slope, measure horizontally to a vertical pole.
- When done measuring, check that A and B measurements add up to the total of all length and width measures.
- Check A and B measures at top of the wall and bottom of the wall, to be sure walls aren't leaning.
- Measure depth from the flat floor, (not the top of any coved sand) - to the bottom of the liner bead track at top of wall.
- Keep your vertical measuring pole straight, or use a plumb bob on a horizontal pole.
Choosing a Replacement Liner
One of the fun parts of putting in a new pool liner is choosing a new pattern or style. Darker colors will absorb slightly more solar energy. Tan and Grey tones have become popular lately, to blend with neutral backyard colors. Most patterns have a mottled pattern, to help hide dirt and mask wrinkles or imperfections. If you can afford it, I would always recommend choosing a thicker liner - 28 or 30 mil, rather than a standard 20 mil pool liner.
Warranty is another way that liner manufacturers differentiate their products, but keep in mind that a true warranty claim, for defects in materials or manufacture, is rare. 99% of liner failures are caused by pool chemistry or Acts of God. Also, most warranties are pro-rated, so a 25 year warranty may have little value over time. Liner warranties typically cover seam or bead separation, but won't cover punctures, or sun or chemical deterioration. Specifically, inground liner warranties only cover you for "defects in materials or workmanship".
When you order a pool liner, you may also consider ordering wall foam and adhesive. If your steel walls are rusty, or to just add a soft feel to your walls, 1/8" thick wall foam is added to the walls before you install the new liner. There are several great liner manufacturers in the states, and lots of good vinyl comes from Canada - some well known liner companies are Pen-Fab, McEwen, Tara, GLI, Swimline.
Choose a pattern and style that you like, you're going to be looking at it for many years!
Supplies & Materials
- Wall Foam and spray adhesive (optional)
- Floor repair materials (sand, vermiculite or concrete)
- Duct Tape
- New faceplates and gaskets for skimmer, returns, main drains
- Possibly new gaskets for steps and pool light
- Pennies or Popsicle sticks
Tools & Equipment
- Razor Knife
- Flat head Screwdrivers
- Putty Knife
- Liner Vac or HD Shop Vac
- Extension cord
- Push Broom
- Cordless Drill with #3 Phillips Tip
Draining the Pool
Wait to drain the pool until you have everything ready to go, and a good weather forecast. Leaving your pool empty for very long could damage the pool walls or floor, if freak weather and floods move in before you have a chance to refill the pool.
A submersible pump can be set in the pool to drain it slowly, in 10-30 hours, depending on the pump size. Some inground pools can drain most of the water out of the pool from the main drains, using the filter pump. If you have a multiport valve, set it to waste, and run out a long discharge hose, away from the pool (and your neighbors!). Close the skimmer valve tightly and keep the pump running (and draining) until the main drains begin to suck air. The remaining water can be removed with a pool cover pump or small submersible pump.
You will need to drain ALL of the water out of the pool. Get the last bit with a mop and bucket, or large sponge, or a shop vac. A few gallons spilled won't hurt the floor of the pool, but don't remove the floor of the liner with inches of water still left in the hopper.
Pool Draining Pitfalls to Avoid:
- Discharge the pool water too close to the pool, and it can weep into the pool, or put pressure on weak walls.
- Water should be balanced and low in sanitizer and algaecides, to protect the watershed. Green water is OK!
- 20,000+ gallons is a lot of water, be sure that you are not eroding or oversaturating a hillside.
- Some areas have pool drainage and discharge restrictions and regulations. Check your local govt. website.
- Don't flood a downhill neighbor's garden, garage or basement!
- Check the weather, flood waters and high water tables can cause problems for an empty pool.
Removing the Liner
With the water removed, first remove the faceplates for the skimmers and returns. Keep the main drain faceplate on until you are ready to install the new liner. Use a large #3 Phillips screwdriver, or use a #3 tip on a cordless drill. Put the screws in a Ziploc bag and place somewhere safe. Same thing with the pool step and seat sections, and the pool light.
For the underwater pool light, you will have to remove the lamp from the wall niche completely. Find the light junction box located off the deck, directly behind the light(s). Shut off the power at the breaker, and disconnect the light cord from the power wires. Attach a wire or heavy string to the light cord and pull it through the conduit as you remove the light fixture from the niche. Leave the string in the light niche, so you can pull the light cord back through the conduit to the junction box, after the liner is installed. Place the pool light, light rings and screws in a safe and secure location. See my other blog post for more information on removing and replacing a pool light.
Now you can cut the liner at the base of the wall with a razor knife, all the way around the pool. Make a few vertical cuts, up the wall, and remove the liner from the track. Be gentle as you pull the liner out of the track. Yanking on it can break a brittle section of the track. Roll up the wall pieces and remove them from the pool. Cut the floor into sections, roll them up and throw them up on deck.
Inspect your walls around the pool. If they are dusty or crusty, you can sweep them with a broom or brush, or scrape off deposits with a putty knife. Rusty walls should be scraped down and painted. If there is more than just slight rust and dust, you should consider using Wall Foam. For walls that have actual holes in them, or very severe rust, you can duct tape sections of sheet metal to the wall, to keep the rust from damaging a new liner. Another good use of duct tape is to cover the vertical wall joints, to help hide the indentation where they meet.
Inspect the liner track at the top of the wall, and clean it out with a hand brush or pool brush. If you have any areas that are cracked or broken, Super Glue makes a quick repair. For missing sections, ask your dealer for a section of liner track. Close up pictures are helpful to find the correct type of liner track, as there are several types.
Inspect the surfaces of the wall where the faceplates attach - skimmer, returns, light and steps. If you see rust, this indicates that it has been leaking. Clean it up as well as you can, using rough sandpaper, steel brush or wire wheel. Paint it with a rust tolerant paint like Rust-O-leum or Krylon. After cleaning the surfaces, use small strips of duct tape to hold on the skimmer, pool light and main drain gasket, the one that goes under the liner (there's a second gasket used on top of the liner).
Sand Floors have the most amount of work. Retroweling a sand floor can take 3-5 hours for two people. Bad sand (green or black) can be removed and replaced, but don't add too much new sand, or you risk raising the floor level, making the liner deeper than the pool depth. Use a rounded edge trowel, and scrape off the high spots and fill in the low spots. Put pressure as you trowel to create as smooth a surface as possible. A little spray of water can help in some spots, but don't oversaturate the sand. Work your way from the deep end to the shallow end, smoothing the floor and picking out any pebbles or debris that may be visible through the liner.
Vermiculite Floors have much less work required. This type of floor looks like rough concrete, but is softer and may have developed divots or cracks. Sweep the floor first, to remove dust and loose material, and then make any needed patches to the floor, using a medium grade of Vermiculite. Trowel into place, spray with water, trowel again if needed - it dries very quickly and is easy to work with.
Concrete floors are the least amount of work. Just sweep them clean and patch any cracks that may have developed on the floor. Use hydraulic cement, or a sand mix cement. Mix with water and trowel into place.
Prep Work Pitfalls to Avoid:
- Be cautious working around an empty pool. Falling into empty pools can be hazardous!
- Be Prepared for the Prep Work, so you can finish wall and floor prep as fast as possible.
- Once the floor is ready - install the liner quickly before debris blows into the empty pool.
- Darker swirl patterns will hide wall and floor imperfections more than light blue liners.
New Liner Installation
Give the floor of the pool one last inspection for anything that might have blown in the pool. Clean off the pool deck if needed, to keep the pool clean. Remove the main drain faceplate, and replace the gasket taping it in place, so the holes line up, and it won't shift while under the liner. Be careful to keep sand out of the main drain ring and cover screw holes.
An inground pool liner box will have an arrow with a label marked Deep End, (or sometimes Shallow End). Lay the liner on the end of the pool and unfold it to the sides. Four people work best for the next few minutes of work, one person for each corner. With two people holding the deep end corners, two other people grab the shallow end corners and walk the liner down to the shallow end. Locate the shallow end corners of the liner, and lining them up, lock the liner into the track. Use Popsicle sticks or pennies if needed to shim the liner bead, and help hold it in the track temporarily. When all four corners (or for Oval pools, an approximation), you can release two helpers, and two people can return to the shallow end of the pool.
Pull Up the Slack: Lay down on the pool deck next to the pool step section, and lean way over the edge to grab the vinyl on the floor. Your helper can do the same on the opposite side of the steps. The purpose is to grab the liner off of the shallow end floor, and pull it towards the shallow end wall, to take up the natural slack that the liner will have towards the deep end. You can place sandbags or Water Bags up against the shallow end wall or under the step section, if it seems that you need it to help prevent the liner from slipping toward the deep end.
Lock in the Bead: Two people work in opposite directions, locking the liner bead into the track. Start in the shallow end center, and pull opposite each other, to remove small amounts of slack, while keeping the corners in place. If you have a step section in the shallow end, you can use some duct tape for now, to help hold the liner over the span of the steps. Continue all the way around the pool, locking the liner snugly into the track. Do this from outside the pool, leaning over the edge. If the liner fit is either too tight or too loose in the track, you can use strips of Liner Lock, a rubber wedge that you push-in between the liner and the track.
How's it Hanging? After it's all in place, take a look to check the "hang" of the liner. The corners should all be central to the actual corners, although they will be very slack. The wall material should hang straight down, and although loose and wrinkly, any folds should be running vertically. If they run diagonally, you may need to shift the liner in the track somewhat. The vinyl covering the floor should also lay flat, and lift off the floor at the sides, where it meets the wall. Floor wrinkles can be pulled out by leaning over the pool edge and pulling on the liner, or using a push broom or pool brush to push them towards the wall.
Liner Installation Pitfalls to Avoid:
- No smoking around the new liner!
- No sharp instruments, No shoes.
- Install during 65-85 degrees if possible.
- Don't install any faceplates until full.
- Plan your installation, to order all gaskets and faceplates ahead of time.
Setting the Liner
The next step is to use a vacuum to suck out the air behind the liner, or between the liner and the walls and floor. A powerful vacuum or wet/dry vac is used to suction the liner tightly to the walls and floor. This allows you to fill the pool without any wrinkles. Skip this step (or do it improperly) and you'll likely have wrinkles in your new liner.
The pros use a vac blower like the Cyclone Liner Vac, which is also used for blowing out pool lines, to winterize a pool. You can buy one of these, or you can use a heavy duty wet/dry vac, of 5hp or larger. Large inground pools may need two vacuums to set the liner.
Set up the vac on the edge of the pool, in the middle of a long side. Run an extension cord to a nearby outlet. Connect a 4-6' hose to the suction port of the blower/vac, and run the hose behind the liner, by pulling a small section of liner bead out of the track. Push it down behind the liner a few feet, about a foot above the floor.
Duct tape all around the point where the hose goes behind the liner, to seal up any air leaks around the hose. Also use duct tape on the skimmer lid, and make sure that all plumbing valves on your filter system are closed.
Step Sections: There are several ways to seal up the step. In some cases you can just use a lot of duct tape, but for larger steps, you'll need to lay something flat across the top of the steps, and duct tape that to the deck and to the liner, to be able to achieve a full seal. A large flat sign, or cardboard sheet can be used. Some people cut a large section from the old liner and lay that across the steps, taping or weighting it down. Lumber can also be used, such as several 1x12" boards laid across the top. You may ask "why not just put on the step tracks and screws?" That is done later, after the liner has stretched into place. Don't make any holes for the step section, until the water level is up to the bottom step.
When you seal up all of the air leaks, you will see the liner magically suck itself tight in just a few minutes. And now you can really see how the liner fits, how it meets the corners - and if there are any wrinkles.
Wrinkles: Don't freak out if you see a few wrinkles, it's normal. Most pools have a few at first, it just takes some finesse to work them out, by pushing and pulling them towards the wall, or expanding them across the floor. Try to do the work from up above if you have a sand floor, or use two 2'x3' boards to gently move around the floor. Even with vermiculite or concrete floors, try not to enter the pool, and if you must, walk very gently.
To work out wrinkles in a liner, you can use your hands to "massage" or spread out the wrinkle. Try laying on the deck and leaning way over the edge, grabbing a handful of vinyl (you may have to shut off the vacuum temporarily), and pulling towards the wall, and releasing the liner slowly into place. You could also use a push broom or pool brush on a pole, to gently push the vinyl in directions away from the angle of the fold, or wrinkle. Sand bags or water bags can also be used toto hold wrinkles that wIn some cases, you may need to unset and reset the pool liner several times before you get it set without wrinkles. And in some cases, you have to move on, and work on them later. In some cases, the last few wrinkles are most easily worked out when there is a few inches of water covering the area. For more on pool liner wrinkles, see this post dedicated to the topic.
Pool Liner Setting Pitfalls to Avoid:
- If the liner doesn't suck tight in 2-5 minutes, find the air leak and try again.
- Large pools, or L-shapes may need two vacuums for a full set.
- Some wet/dry vacs aren't strong enough for the job.
- Plug into 20A circuits (Kitchen/Garage), with a heavy gauge extension cord, to avoid tripping the breaker.
- Vacuum must run continuously until pool is half full of water, or covering the shallow floor in 3" of water.
Filling the Pool
Before you fill the pool, or when you have just a few inches of water in the hopper bottom, carefully walk down to the deep end and put on the main drain faceplate ring, top gasket and main drain cover. There is already one gasket under the liner, now place a second drain gasket on top of the liner and then screw on the main drain ring, or faceplate. Be sure to tighten down the screws very tight, until you hear the plastic begin to creak. Then, use a razor knife to cut out the vinyl circle inside of the ring, and then install your main drain cover, with two stainless steel screws. Safe drain covers should be an anti-vortex dome design (not a flat grate design), and be secured tightly, to prevent entrapment injury.
Keep the vacuum running until the shallow end is covered in 3-6" of water! If you shut it off, the liner will relax, and you may end up with wrinkles.
From a Garden Hose: Measure your flow by timing how long it takes to fill up a 5 gallon bucket, then you can figure your flow rate, in gallons per minute. A little more math, and you can figure out how long it will take to fill the pool from a hose. Most hoses can do close to 10 gpm, 600 gallons per hour, or 14,400 gallons per 24 hrs.
From a Well: If you have a decent well, with decent water, you can fill your pool with it. I have heard so many people say "Don't want run my well dry, or burn out my pump" - but that is really rare. Most wells can handle filling a pool of 20-30,000 gallons. But, monitor the outflow, and if the flow rate drops considerably, allow the well to catch up, or call in some delivered pool water.
From a Truck: Expensive to do, it can cost $1000 in some areas to fill a pool. In our area, they charge about $250 for the first 5000 gallons, and then $200 for each additional - and they just fill their trucks from fire hydrants!
From a Hydrant: In some towns, if you have a fire hydrant close to your house, you can contact your fire department for a permit to use the fire hydrant to fill your pool. There may be a fee, and you may need to provide your own hose, from the hydrant to your pool, which you can rent for a day.
Remember to continue running the vacuum, to keep the liner set, until the water level is up to the first step in the shallow end. Then you can shut it off, and carefully remove the hose from behind the liner. Remove all of your duct tape and lock the liner back into the track, and continue filling the pool!
Wrinkles: Monitor the pool for wrinkles as it fills, or check the small ones that you saw earlier, to be sure they are stretched out. Some wrinkles just naturally flatten when a few inches of water is on top of them, and the weight of a few inches of water can be helpful in smoothing out wrinkles in the floor, by pushing them toward the wall, or spreading them out. If there is too much water on top of a wrinkle, say more than a foot, it can be harder to pull them out. If you have a sand bottom, you can sometimes push wrinkles in, to the floor, if they are very small folds.
Pool Filling Pitfalls to Avoid:
- No tripped breakers! Plug into a strong 20 amp outlet, keep the vac plug dry if raining.
- Wait to install step, light, skimmer and return faceplates until water level is up to them.
- Don't fill over your vac hose, it can be hard to remove when under water.
- Corded electic drills can be hazardous around pool water (cordless is ok).
Steps & Seats
When the water level reaches the point where it's almost reached the first step, or bottom step, it's time to screw on the step strips, the 3 long plates and about 50 screws, that gaskets the liner around the steps. If the liner looks loose or is wrinkled, pull up on it, or push out on it. If necessary, use small sand bags to help hold the liner up against the wall, under the step.
Gaskets: Most step sections have a heavy duty rubber step gasket that holds up to many liner changes. If you noticed rust around the step strips, inspect the gasketing and replace the heavy rubber gasket if necessary.
To install the step strips, start with the bottom strip, and with a cordless drill, screw all of the bottom strip screws in place, starting in the center and working your way to the outside. Then you can install the side strips, working from the bottom towards the top. Once all 3 step strips are screwed on, go over each one again to make sure they are double-tight. Then, trim out the vinyl carefully and close to the edge of the step strip. Install the screw hider strips and you're done!
Steps and Seats Pitfalls to Avoid
- Without water in the pool, be gentle on the step section, it could crack.
- Clean the step gasket, or use the step gasket kit if it looks damaged.
- Don't use an electric drill, if you drop it in the pool, you could die!
- Don't pull up on the liner as you make your initial screw holes, leave a little slack.
- Wait until the water is up to the screw holes before screwing in the bottom step strip.
The face plates for your skimmer and return should be replaced if they have some age to them. Returns have a permanent rubber gasket, like a step section, but also use a gasket on top of the liner. Buy your skimmer gaskets and main drain gaskets in pairs, once goes under the liner, and one gasket on top of the liner.
Screw on your faceplate screws very tightly, with the large Phillips (#3) head. Crank them down until you hear the plastic squeak and creak. Now you can cut out the vinyl inside the faceplate, trimming it close to the edge with a razor knife.
Pool lights also have a large gasket beneath the ring, and usually a second gasket beneath the vinyl. It would be wise to replace these gaskets when you replace your liner. Vinyl pool light niche gaskets are found in the category of light niche parts. When the water level is up to the bottom of the light, have someone with long arms lean way over the edge of the pool and screw on the large light niche ring and gasket. Then cut out the vinyl inside the ring. Float the pool light across the pool, and hook/duct tape your string/wire to the pool light cord. At the pool light junction box, pull up on the string/wire to pull the pool light cord back into the conduit, and into the j-box, where the power can be reconnected and turned on again. Leave 3-4 feet of cord coiled up inside the light niche, to be able to pull the light out for future repair.
Faceplate Pitfalls to Avoid
- Make sure your replacement gaskets and faceplates are exact match before liner day.
- You need all of the screws - if missing one, find a factory replacement fast.
- Don't use incorrect screws, or non-stainless steel screws. Only Skimmer Screws.
- Don't use an electric drill, but a long handled #3 Phillips screwdriver, or #3 tip on a cordless drill.
- Leave enough cord behind an electric light to pull it up on deck for service.
- Don't poke any screw holes until the water level is up to the bottom of the light ring.
- Don't cut out the vinyl inside until the faceplate or ring is installed.
Thanks for Reading!