Preparation
Start with a structurally sound, clean and fully dry surface. Choose the correct prep method for concrete, gunnite or fiberglass before coating.
Build your system
Choose the right bundle for your pool project
Start by selecting the setup that fits your pool surface and waterproofing needs. Then use the prep and application steps below to complete the job with confidence.
How to use this product
Masking
Mask off all surrounding areas that should not receive coating, then remove the tape before the material has fully cured.
Applying Coat
Apply thin, even coats with alternating directions, then inspect the surface for pinholes, voids and thin spots before moving on.
Curing Time
Let the coating cure based on temperature and humidity, and allow about 6 to 7 days before exposing a submerged application to water.
Additional Information
Review reinforcement, thickness and submerged-application requirements before starting so the project performs correctly long term.
Step by step
How to waterproof a pool with Liquid Membrane
Follow these steps for prep, application and cure timing based on the pool surface you are coating. The goal is a clean substrate, even coverage and enough cure time before water exposure.
1
Prepare your space and gather your materials
• For concrete or gunnite surfaces, use Preparation D to remove mineral deposits or efflorescence. Recommended cleaners: Nu-Lift Cleaner and Stone Soap.
• For fiberglass surfaces, sand the entire surface first with 60 grit, then use Preparation B. Recommended cleaners: Power Cleaner and Stone Soap.
Ensure all surfaces are fully cleaned and dried before you begin, and gather the products and tools needed for the full project.
Helpful Tip
If you need help choosing the right prep cleaners, use the live chat or call the SEMCO team before starting.
2
Fabric reinforcement
If you have any cracks wider than 1/4 inch, use Fabric Reinforcement to bridge them. Cracks smaller than 1/4 inch width can be coated over directly with SEMCO Liquid Membrane.
3
Masking
Mask off all areas that should not receive coating. Remove masking tape before the material has fully cured.
4
Applying coat
Use a 1/2 inch nap roller. Allow any pre-treated areas to fully dry first. Apply a thin coat, about 0.015 inch per coat, with brush or roller over the full substrate including pre-treated areas.
Once the surface can be walked on without residue or fingerprint impressions, apply another thin coat in an alternate direction. Inspect the final surface for pinholes, voids, thin spots or other defects and touch up where needed.
Required total thickness is 0.03 to 0.04 inches for non-submerged applications. For submerged applications, a minimum required total thickness of 60 mil is needed. Allow 6 to 7 days of full cure before filling with water.
Helpful Tip
For submerged applications, SEMCO recommends adding Extra Pigment for a more solid overall finish.
5
Curing time
Curing time depends on temperature, humidity and airflow, but the typical initial cure window is about 6 to 7 days according to the product recommendations.
6
Additional information
• Clean brushes and rollers with warm water immediately after use.
• Proper surface preparation is strongly recommended for the best bond and long-term performance.
• Stir the product thoroughly before use so the color pigments are fully mixed.
• Avoid applying in direct afternoon sun or in temperatures above 85F so the product does not dry too quickly.
• Do not apply to wet substrates or substrates still containing moisture, otherwise the product may not cure correctly and can stay tacky.
• For fully submerged applications, use 3 coats at 20 mil each and coat the full surface above the waterline.
• On non-porous surfaces such as metal or fiberglass, apply thin coats so the product can cure faster.
• If coats were applied too thick and the surface stays tacky, apply a very thin coat over the full surface and allow it to fully cure before exposing it to water.
• Pool plaster may require extended cure time because plaster holds more moisture and needs to breathe out first.
• Test a small inconspicuous area first to confirm adhesion before full application.
• If you have multiple containers, mix them together or reserve one container for the final coat to improve color consistency.
Pool project FAQs
What is the coverage of SEMCO Liquid Membrane™?
The coverage of SEMCO Liquid Membrane™ is approximately 200 to 250 sq ft per gallon at 2 coats, with each coat at 20 mil. For fully submerged or below-grade applications, 3 coats are recommended and coverage is then about 100 to 150 sq ft per gallon. Coverage may vary depending on substrate porosity. For corrugated metal, calculate at least 33% extra material.
What is the cost of SEMCO Liquid Membrane™?
One gallon of SEMCO Liquid Membrane™ costs $109.90 and typically covers about 200 to 250 sq ft for 2 coats. At the low end of coverage, that works out to about $0.43 per square foot.
Can tile be applied on top of SEMCO Liquid Membrane™?
Yes. SEMCO Liquid Membrane™ can be applied to the substrate as a primary waterproofing layer and tile can then be installed over it with your mortar or thin-set system.
Can one paint over SEMCO Liquid Membrane™?
Yes. A urethane-based or water-based acrylic paint is recommended if you want to paint over SEMCO Liquid Membrane™.
How to apply SEMCO Liquid Membrane™?
Application depends on the substrate. For pools, ponds and other submerged applications, use SEMCO Nu-Lift Cleaner and Stone Soap to remove mineral deposits or efflorescence and remove any loose paint or coating. For roller or brush application, use a 1/2 inch nap roller and apply thin coats over the full substrate, allowing each coat to dry to the touch before recoating. Inspect the final surface for pinholes, voids and thin spots, then use additional product to seal defects. For submerged applications, 3 coats at 20 mil each are required.
Why does my SEMCO Liquid Membrane™ discolor when getting in contact with water?
Discoloration is usually a sign that the SEMCO Liquid Membrane™ has not fully cured yet, but it does not affect the waterproofing capability. It is important to follow the recommended preparation, recoating times and coat thickness. Any deviation may significantly increase drying and curing times.
What if I have already filled the pool, fountain or pond with water?
It is best to drain the pool, fountain or pond and allow curing to happen. If you are unsure, reach out to customer service by phone, email or live chat before proceeding.