How to Prep a Pool for a New Plaster Job

Written by Michael Dean
June 28, 2023

prepping a swimming pool for plaster

Plastering a pool is a huge undertaking that involves a lot of time and effort. Therefore, properly prepping your pool for the process is one of the most critical steps. Without adequate prep, your plaster may not cure correctly and may lead to unnecessary damage to your pool.

In this article, I will explain the step-by-step process of preparing your pool for plastering and answer frequently asked questions about the replastering process.

Main Takeaways

  • To prepare a pool for plaster, drain the pool, relieve hydrostatic pressure, remove fittings, acid wash the pool, and apply a bond coat.
  • Relieve hydrostatic pressure by not draining after heavy rainfall, draining away from the pool area, and unplugging all hydrostatic relief valves.
  • Prepping a pool for plaster is vital for successful curing of the plaster.
  • Pool plaster will last around 10-15 years on average unless there are signs of degradation.

Step-By-Step Guide: How to Prep a Pool For Plaster 

Prepping a swimming pool for plastering is not a simple case of draining the water. The prepping process can be pretty daunting, so let’s break everything down step-by-step.

Supplies Checklist

  • Pressure washer
  • Acid resistant bucket
  • Muriatic acid
  • Grinder
  • Chisel
  • Hammer
  • Sander
  • Bond coat
  • Paint roller

Step 1: Drain the Pool

The first step in preparation for plastering is to drain the pool water. Professional pool companies will use a submersible pump to drain the water. If you are draining the pool yourself, you can drain most of the water using the filter pump, and the last little bit can be emptied using a submersible pump.

Another DIY method of getting that leftover water out of your pool is to use a wet vacuum or, the old-fashioned way, using a large bucket and sponge.

It is essential to drain the pool water away from the pool area and not into the surrounding area, and you want to keep the ground around the pool as dry as possible to avoid the ground sinking.

Many pool experts recommend draining pool water at 12 gallons per minute. 

Step 2: Relieve Hydrostatic Pressure

Many people do not know about hydrostatic pressure and what happens when you suddenly remove all the water from your swimming pool. Hydrostatic pressure refers to the force of the water that pushes down against the pool walls. When you remove that weight, there’s a chance of the pool surface springing up.

To prevent this, you need to open the hydrostatic relief valves found on the pool floor. Most pools have between 4-6 valves. Avoid draining the pool after heavy rainfall, as water accumulates in the ground and under the pool. And if there’s water underneath, it can push the pool up from above the ground.

Step 3: Remove Any Fittings

Once the pool has been appropriately drained while relieving hydrostatic pressure, remove all fittings from the pool. Remove all fittings, like the light fittings, wall fittings, and drain covers. Once the fittings have been removed and stored safely, place tape over the drain holes to prevent any plaster dust and debris from getting inside.

Step 4: Cutting and Chipping

It is strongly recommended to have a professional do this step. Cut ½ an inch of plaster under the tile line (if you have tile) using a grinder so that the plaster has something to grab onto. Any tiles used on the steps can be cut or chipped away. Using a chisel and hammer, remove all the plaster around any fittings as well.

When chipping the plaster around the fittings, check for any leaks or holes, as these need to be filled in before you can replaster the pool. Rough edges and bumps must be chipped away and sanded down.

Step 5: Inspect the Pool For Any Blemishes

Before proceeding with the rest of the prep work, check for cracks, rust spots, and delaminations. Generally, the only cracks to worry about are those big enough to fit screwdrivers. If you find any sizeable cracks, cut them open wider; while it may seem counterintuitive, the new plaster will be filled inside.

The same goes for rust spots and delaminations. Delaminations are small hollows that form when calcium matures; these hollows are formed inside the old coat of plaster. An easy way to check for these delaminations is to tap the pool surface, listening for hollow sounds. The hollow will need to be chipped open and away until you reach solid plaster.

Step 6: Acid Wash the Pool

Once all cracks and blemishes have been chipped away, apply a layer of muriatic acid to the surfaces to acid wash the pool plaster. Leave this acid to soak on the surface for a couple of minutes. After rinsing the acid off the surface, add soda ash to the collected water before pumping it out. This neutralizes the wastewater that needs to be drained.

Step 7: Pressure Wash the Pool

It is a good idea to pressure wash the pool to ensure that all the acid wash and any stubborn grit have been removed from the pool’s surface. Then, the leftover water will need to be pumped from the pool. 

Step 8: Apply a Bond Coat

The final step in prepping the pool for plastering is to apply a bond coat. This bond coat can sometimes have a quartz or silica finish to strengthen the coat. The bond coat can be used with a paint roller for ease.

Depending on the weather and the pool size, this bond coat can take around 7 hours to dry thoroughly.

Only once the coat is dry can you begin finally plastering the pool.

Why Should You Prep the Pool For Plaster?

Preparing your pool for plastering is essential to ensure the plaster cures successfully. All of the above steps are essential to replastering a pool.

If you do not remove the cracks or hollows beforehand, they will eventually grow, split, or cause the new plaster to bubble and result in a sub-par plaster job. The rough edges and bumps that should be sanded down are to ensure that the new plaster is applied to a smooth and even surface. Finally, acid washing will ensure that any mold or algae are washed away so that nothing grows underneath the new plaster.

Plastering a pool is not a cheap task, so do everything you can to ensure the plaster lasts a long time.

How Often Should I Replaster My Pool?

If the plaster has cured correctly, it should last around 10-15 years before you need to replaster the pool again. However, this is not always the case; things like extreme weather and poor quality plaster can shorten their lifespan. Alternatively, more expensive and durable plaster finishes like quartz can extend the plaster’s lifespan by another five years.

Besides the age of the plaster, here are some additional signs that you need to replaster your pool:

  • Stubborn surface stains
  • Spiderweb cracks
  • Rough surface
  • Plaster flaking or peeling
  • Erosion marks
  • Corroded tile grout
  • Unexplained drop in the pool water level
  • Discolorations in the plaster

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What is the Pool Plaster Process?

Once all the prep work is complete and the bond coat has thoroughly dried, the plastering process can begin. Plastering will start from the deep end of the pool, working towards the shallow end. Your pool builder will use a trowel to apply a ⅜-inch thick layer of plaster. They will smooth it on the pool’s surfaces and apply it evenly until the entire surface is covered.

When the first layer is dried to touch, they will apply a second layer. If the pool has any tiles or coping, your builder will re-tile them at this point while the plaster is still wet. When all the plaster has been applied, they will scrub the surface of the pool to remove loose plaster, dust, and debris. Finally, they will inspect the plaster thoroughly to ensure there are no cracks. When all the steps are complete, you can refill the pool. The final and crucial step in the pool plaster process is to brush the plaster twice daily.

If you have any other questions regarding pool plastering or your pool in general, feel free to reach out. I am always happy to help!

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