Description
Classi Seal Waterproofing Strip — Sold Per Metre — Self-Adhesive — 15mm Movement
The Classi Seal Waterproofing Strip is a professional self-adhesive tanking strip designed to create a reliable secondary waterproof seal between shower trays or baths and bathroom walls. Applied before installation, it creates a flexible membrane behind the tiles that accommodates up to 15mm of building movement — providing far superior long-term protection compared to silicone sealant alone. Sold per metre, cut fresh from a 25m roll, so you order exactly what you need with no waste.
📏 Sold per metre — enter the quantity in metres at checkout.
Quantity 3 = 3 metres (£36) · Quantity 5 = 5 metres (£60) · Quantity 10 = 10 metres (£120)
How much do you need? Standard shower tray or bath (3 sides): approx. 3–3.5m · Large enclosure: 4–5m · Add 10% for trimming.
Key Features
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Sold per metre — cut to your exact length from a 25m roll; no waste
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Self-adhesive backing — pressure-sensitive; quick, clean installation
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15mm movement accommodation — flexes with building settlement without compromising the seal
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Tile immediately — no curing time required after application
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Superior to silicone alone — creates a waterproof membrane behind the tiles
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Flexible strip — conforms to shower tray and bath edges
Technical Specification
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Brand: Classi
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SKU: CS025
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Type: Self-adhesive flexible waterproofing tanking strip
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Sold: Per metre (cut from 25m roll)
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Width: 100–120mm (upstand + base)
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Weight: 0.15kg per metre
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Movement accommodation: Up to 15mm
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Adhesive: Pressure-sensitive self-adhesive backing
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Material: Flexible waterproof membrane
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Application temperature: 5°C to 35°C
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Suitable surfaces: Clean, dry, dust-free
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Finish: Tile over upstand; seal base with neutral cure silicone
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Maximum roll length: 25 metres
How It Works
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Prepare: Ensure tray or bath edges are clean, dry, and dust-free
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Apply: Remove backing and press Classi Seal firmly to the wall-facing edges of the tray or bath
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Position: Install the tray or bath — the upstand extends up the wall
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Tile: Apply tiles over the upstand immediately — no curing wait
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Seal: Apply neutral cure silicone to the bottom edge once tiling is complete
Suitable For
- Shower tray to wall junctions — typically 3–3.5m for a standard 3-sided installation
- Bath to wall junctions — typically 3–3.5m for a standard 3-sided installation
- Wet room former edges — measure perimeter and add 10% for trimming.
- Large shower enclosures — typically 4–5m
- Commercial bathrooms — hotels, gyms, care facilities
- Multiple projects — order longer lengths to cover several bathrooms
Also Available
Frequently Asked Questions
How do I order the right length?
Enter the number of metres you need as the quantity at checkout. For example, quantity 3 = 3 metres (£36), quantity 5 = 5 metres (£60). We cut your exact length fresh from a 25m roll. As a guide: a standard shower tray or bath on 3 sides requires approximately 3–3.5 metres. Add 10% for trimming. If in doubt, order slightly more — offcuts can be used for future repairs or smaller projects.
Why use a tanking strip instead of silicone alone?
Silicone sealant is the first line of defence but has limitations — building movement, settlement, and thermal expansion can cause silicone to crack or separate over time. Classi Seal provides a critical secondary barrier: a flexible waterproof membrane behind the tiles that accommodates up to 15mm of movement without failing. Even if the silicone joint cracks, the tanking strip prevents water from reaching the substrate. This dual-layer approach is considered best practice by professional bathroom installers and helps meet UK Building Regulations Part C requirements for wet areas.
Can I tile immediately after applying Classi Seal?
Yes — one of the key advantages of Classi Seal is that no curing time is required. Once the strip is applied and the tray or bath is positioned, you can tile over the upstand immediately. The base edge should be sealed with neutral cure silicone once tiling is complete.
What type of silicone should I use with Classi Seal?
Always use neutral cure silicone (not acetic/vinegar cure). Acetic cure silicone releases acetic acid during curing, which can damage the adhesive and membrane of the strip. Neutral cure silicone is widely available and is the correct choice for use with tanking strips and most bathroom materials.
What surfaces is Classi Seal suitable for?
Classi Seal is suitable for clean, dry, dust-free surfaces. Ensure the edges of the shower tray or bath are free from grease, dust, and moisture before application. Apply in temperatures between 5°C and 35°C for best adhesion.
Is there a pre-cut version available?
Yes — if you need a standard length for a single installation, a pre-cut 3.2m version is also available. The per-metre option (this product) is ideal when you need a specific custom length, are completing multiple bathrooms, or want to avoid waste from a pre-cut length that may not suit your installation.
Can I order if the item shows as out of stock?
Yes — this product is available to order even when stock shows as zero. Please allow additional lead time and contact us on 01603 381095 to confirm availability.
