Composeal Blue Vinyl Shower Pan Membrane Installation Guide
Flexible Waterproofing Membrane for Tile Showers, Floors, Walls, Roof Decks, Terraces, and Thick-Bed Tile Installations
Composeal Blue Vinyl Shower Pan Membrane is a flexible PVC waterproofing membrane designed for concealed waterproofing applications beneath tile, stone, and mortar bed installations. Available in 30 mil and 40 mil thicknesses, Composeal Blue has been trusted by contractors, builders, architects, and homeowners for decades as a dependable waterproofing solution.
Unlike pre-formed plastic or metal pans that are limited to fixed dimensions, Composeal Blue can be custom-fitted to virtually any shower size, drain location, or waterproofing application. This flexibility makes it ideal for both new construction and remodeling projects.
Product Overview
Composeal Blue is manufactured from durable flexible PVC and is available in 48-inch, 60-inch, and 72-inch widths. Rolls are available in both 50-foot and 100-foot lengths to accommodate projects of various sizes.
The membrane is designed to provide long-term waterproof protection beneath mortar bed tile installations while maintaining flexibility and resistance to moisture, chemicals, mold, mildew, and environmental exposure.
Common Applications
- Tile shower pans
- Roman tubs
- Whirlpool bath enclosures
- Waterproof flooring systems
- Roof decks and terraces
- Balconies and exterior waterproofing projects
- Commercial waterproofing applications
- Renovation and remodeling projects
- Mortar bed tile installations
- Outdoor ice rink liners in cold climates
Why Waterproofing Matters
Proper waterproofing is one of the most critical components of any tile shower or wet-area installation. Water that penetrates beneath tile surfaces can damage framing, subfloors, insulation, and surrounding building materials.
Composeal Blue creates a durable waterproof barrier beneath the finished tile assembly, helping protect the structure from water intrusion while supporting long-term tile performance.
Overall Product Installation
Composeal Blue is typically installed beneath a traditional thick-bed mortar system ranging from approximately 1¼ inches to 2 inches in thickness over wood or concrete substrates. When properly installed, the membrane provides dependable waterproof protection for the life of the installation.
Installation Requirements Before You Begin
Before installing Composeal Blue, verify that the substrate is structurally sound, clean, and properly sloped toward the drain. Proper preparation helps ensure successful waterproofing performance and long-term durability.
Installation Instructions
Proper installation of Composeal Blue is essential for achieving a long-lasting waterproof shower pan assembly. Before beginning, ensure the substrate is properly prepared and all plumbing components are correctly positioned.
Step 1: Prepare the Subfloor
Before placing the membrane, verify that the subfloor is sloped toward the drain at approximately 1/4 inch per foot. If necessary, create the slope using a cement mortar bed.
The substrate should be clean, dry, and free of debris, loose materials, protruding fasteners, gravel, and other objects that could damage the membrane.
Step 2: Install Wall Turn-Ups
Extend the membrane up surrounding walls a minimum of 3 inches above the finished curb height. Allow sufficient material to continue over and down the outside face of the curb where required.
Proper wall turn-ups are critical for creating a fully waterproof shower pan assembly.
Step 3: Prepare Wall Studs
For wood-framed walls, notch the studs approximately 1/2 inch to accommodate the thickness of the membrane and corner folds. This allows the finished wall surface to remain plumb without bulging.
For metal stud construction, install furring strips above the membrane height to create a flush wall surface.
Step 4: Fasten the Membrane Correctly
Fasteners should be placed no lower than 3 inches above the finished curb height.
Use flat-head roofing nails or staples on wood framing. For metal studs, use corrosion-resistant screws with washers.
Never place fasteners through the membrane in areas exposed to standing water.
Step 5: Form the Corners
Fold outside corners as required while keeping the membrane intact. Do not cut membrane corners.
To maintain a flat wall surface, position folded material between notched studs or behind furring strips.
Pre-formed corner protectors may be used to reinforce critical waterproofing areas around curbs and transitions.
Step 6: Install the Drain Assembly
Composeal Blue should be used with a bolt-down clamping-ring style drain equipped with functioning weep holes.
Position the drain so the lower flange sits flush with the sloped subfloor.
Cut the membrane opening precisely to match the drain opening. Do not cut oversized openings and do not remove material around the bolt holes. Instead, carefully pierce the membrane to allow a tight fit around the bolts.
Step 7: Seal and Clamp the Drain
Apply butyl caulk or an approved equivalent between the membrane and the lower drain flange.
Install the clamping ring and tighten all bolts evenly to create a watertight seal.
Proper drain sealing is one of the most important steps in any waterproof shower pan installation.
Step 8: Protect the Weep Holes
Place clean gravel, spacers, or another approved porous material around the drain weep holes before placing the mortar bed.
This prevents mortar from blocking drainage pathways and allows moisture beneath the tile assembly to properly reach the drain system.
Step 9: Perform a Flood Test
Plug the drain and fill the completed shower pan with water.
Allow the water to remain in place for a minimum of 24 hours to verify the waterproof integrity of the installation.
If no leaks or water loss are observed, the shower pan is ready for completion of the mortar bed and tile installation.
Code Requirements
Under UPC/IAPMO plumbing code jurisdictions, a 15-pound felt underlayment may be required beneath 30 mil shower pan liners. Local code requirements should always be verified before installation.
Composeal 40 mil membranes generally do not require this underlayment and are approved for use in many jurisdictions without additional protection beneath the liner.
Components and Accessories
Pre-Formed Corner and Curb Protectors
Composeal's multi-purpose pre-formed corner and curb protectors are designed to reinforce waterproofing at curbs, transitions, and other critical areas of the installation.
These protectors are supplied in pairs and can be used at outside corners where additional waterproofing protection is desired. Using pre-formed accessories helps simplify installation and reduces the risk of improper corner detailing.
Composeal does not recommend cutting inside corners because doing so may weaken the waterproofing assembly.
Codes, Certifications and Compliance
Composeal 30 and Composeal 40 comply with the three major plumbing code standards including UPC-IAPMO, SBCCI, and BOCA requirements.
Composeal has also received separate municipal approvals where required, including jurisdictions such as the City of Los Angeles, City of Philadelphia, Metropolitan Dade County, and the Commonwealth of Massachusetts.
In addition, Composeal complies with Corps of Engineers specifications for PVC shower pan materials and meets the requirements of FHA Publication 4900.1.
These certifications help demonstrate the product's long-term performance and suitability for demanding waterproofing applications.
Warranty Information
Composeal 30 and 40 are warranted against failure of the membrane itself. In the event of material failure, replacement membrane will be supplied at no charge.
This warranty applies only to the membrane product and does not extend to installation methods, labor costs, or consequential damages beyond the manufacturer's control.
Under normal installation and service conditions, Composeal membranes are designed to provide waterproof protection for the life of the building.
Operation and Maintenance
Composeal requires no routine maintenance after installation. Once properly installed beneath the tile assembly, the membrane remains protected and should provide long-term waterproofing performance throughout the life of the structure.
Cement Welding and Seaming Procedures
Composeal sheets may be joined using approved Compotite flexible PVC solvent cement.
For proper seam construction, overlap adjacent membrane sheets by a minimum of 2 inches with the upper sheet positioned in the direction of water flow.
Apply approved PVC cement to both surfaces and allow the adhesive to become tacky, typically within approximately two minutes.
Join the surfaces together and roll the seam first lightly to prevent slippage and then firmly to achieve complete bonding.
Only Compotite-approved PVC cement should be used when welding or seaming Composeal membranes.
Technical Data and Performance
Composeal 30 and Composeal 40 meet or exceed the engineering requirements established by ASTM D4551 for flexible PVC sheeting used in concealed waterproofing applications.
These standards are intended for waterproof membranes used in environments where long-term reliability and protection from costly water damage are essential.
Independent laboratory testing has verified compliance with ASTM requirements for tensile strength, elongation, tear resistance, puncture resistance, chemical resistance, hydrostatic pressure performance, seam strength, and dimensional stability.
Testing has demonstrated excellent resistance to mold, mildew, fungus growth, water penetration, and common environmental exposures encountered in tile shower and waterproof flooring installations.
Engineering Data Table
| Engineering Properties | ASTM D 4551 Spec Grade 30 |
ASTM D 4551 Spec Grade 40 |
Composeal Test Results .030 | Composeal Test Results .040 |
|---|---|---|---|---|
| Thickness, inches | 0.30″ | 0.40″ | 0.31″ | 0.42 |
| Tensile Strength. lbs/in. width | 60-lb min. | 80-lb min. | 89-lb (2870 psi) | 113-lb (2700 psi) |
| Tensile Strength. at 100% elongation | 30-lb min. | 40-lb min. | 43-lb | 57-lb |
| Ultimate elongation before breaking | 300% Min | 300% Min | 400% + | 400% + |
| Tear Resistance. lbs/in width | 185-lb min. | 250-lb min. | 260-lb | 263-lb |
| Pinholes | None | None | None | None |
| Micro-Organism Resistance (fungus, mildew, mold) | No Growth | No Growth | No Growth | No Growth |
| Chemical Resistance: | ||||
| Distilled H2O % wt. change* | 1% max | 1% max | + 0.4% | + 0.4% |
| Soapy H2O % wt. change* | 2% max | 2% max | + 0.5% | + 0.3% |
| Alkali, pass/fail (hydrostatic) | Pass | Pass | Pass | Pass |
| Shrinkage, dimension change at 158 F ASTM 1204 | 5% max | 5% max | 1.3% | 2.9% |
| Volatility, % loss at 158 F after aging | 1.5% max | 1.5% max | None | None |
| Hydrostatic pressure (to test water penetration): | ||||
| Original Condition | Pass | Pass | Pass | Pass |
| After Folding test (cold crack, 4hrs @ 0F) | Pass | Pass | Pass | Pass |
| After Puncture test | Pass | Pass | Pass | Pass |
| After Indentation test | Pass | Pass | Pass | Pass |
No evidence of surface wetness or other signs of water penetration was detected on any of the tested specimens.
Additional Test :
Seam, (lap joint) strength ASTM D751 CTI Standard – 8 lbs/in. min. / Composeal 30 – 69 lbs/inch / Composeal 40 – 85 lbs/inch
Specific Gravity: 1.29 @ g/cm3
Cold Crack: passed @ 53 F
ASTM Standard D1004, d 412 d1790, e 96 and FHA Spec. 4900.1 are also met by Composeal
*Measure of water/ chemical surface absorption
Made in USA
Frequently Asked Questions
What is Composeal Blue used for?
Composeal Blue is a flexible PVC waterproofing membrane primarily used for tile shower pans, Roman tubs, whirlpool bath enclosures, roof decks, terraces, and other concealed waterproofing applications beneath tile and mortar bed installations.
Can Composeal Blue be used in custom shower designs?
Yes. Unlike pre-formed shower pans, Composeal Blue can be cut and formed to fit virtually any shower size, shape, curb configuration, or drain location.
Can Composeal Blue be used over wood or concrete substrates?
Yes. Composeal Blue is commonly installed over both wood and concrete substrates when properly prepared according to manufacturer recommendations.
How long should a shower pan be flood tested?
A completed shower pan should generally be flood tested for a minimum of 24 hours before proceeding with the mortar bed and tile installation.
Does Composeal Blue require maintenance?
No. Once properly installed beneath the tile assembly, Composeal Blue requires no routine maintenance and is designed to provide waterproof protection for the life of the building.
Can Composeal Blue be welded or seamed?
Yes. Composeal Blue sheets can be joined using approved Compotite flexible PVC solvent cement, creating strong waterproof seams when installed according to manufacturer guidelines.
Helpful Resources
- Composeal Gold Installation Guide
- Composeal Waterproofing Videos and Product Overview
- Composeal Gold Radiant Floor Heating Installation Guide
- Solution for Types of Concrete Cracks
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Final Thoughts
Composeal Blue Vinyl Shower Pan Membrane has been trusted for decades as a proven waterproofing solution for tile shower construction, mortar bed flooring systems, roof decks, terraces, and other demanding waterproofing applications. Its flexibility, durability, and long-term performance make it a popular choice among contractors, builders, and homeowners.
When properly installed with appropriate drain assemblies, corner detailing, seam welding, and flood testing procedures, Composeal Blue provides dependable waterproof protection that can last for the life of the building.
Whether you are building a traditional tile shower, remodeling a bathroom, or constructing a custom waterproofing system, Composeal Blue remains a trusted solution for long-term moisture protection beneath tile and stone installations.