Flexi-Seal Waterproofing Strip — 4.0m Pre-Cut — Flexible Rubber — Large Baths & Shower Trays
The Flexi-Seal 4.0m Waterproofing Strip is a professional flexible rubber seal that creates a permanent, watertight barrier between shower trays, baths, or worktops and bathroom walls. The butyl-based adhesive strip bonds securely to the tray or bath edge; tiles or wall panels are then fitted directly over the seal. The flexible rubber construction accommodates building movement and settlement without compromising the waterproof barrier. Independently tested to BS EN 28510-1 1993. The 4.0m pre-cut length provides generous coverage for large baths, P-shaped and L-shaped baths, and full-size shower trays.
✅ Pre-cut 4.0m — ready to use. Ideal for large baths (1700–1800mm), P-shaped and L-shaped baths, and full-size shower trays (900–1200mm) on 3 sides. For standard installations, see the Flexi-Seal 2.0m strip or the Classi Seal 3.2m strip.
Key Features
4.0m pre-cut length — generous coverage for large baths, P-shaped baths, and full-size shower trays
Flexible rubber construction — accommodates building movement and settlement
Butyl-based adhesive — integrated adhesive strip; secure, permanent bond
Concealed installation — tiles or wall panels fit directly over the seal
BS EN 28510-1 1993 tested — independently tested to British and European standards
Suitable for shower trays, baths, and worktops
Prevents water damage — protects against leakage at vulnerable wall junctions
Technical Specification
Brand: Spajet
SKU: FLEXI14
EAN: 5060134754946
Type: Flexible rubber waterproofing strip
Length: 4.0 metres (pre-cut)
Width: 100–120mm (upstand + base)
Weight: 0.8kg
Material: Flexible rubber
Adhesive: Butyl-based integrated adhesive strip
Testing: BS EN 28510-1 1993 (pressure-sensitive adhesive tapes)
Application temperature: 5°C to 35°C
Suitable surfaces: Clean, dry, dust-free
Coverage: Large baths, P-shaped baths, full-size shower trays, extended worktops
Finish: Tile or panel over seal; silicone at base edge
Coverage Guide
Use these examples to confirm the 4.0m length suits your installation:
Standard 1700mm bath — 3 sides: 2 × 1700mm + 700mm end = 4,100mm — 4.0m provides near-complete coverage; trim the short end slightly or use a small offcut
1200mm shower tray — 3 sides: 2 × 1200mm + 800mm = 3,200mm — 4.0m provides complete coverage with 800mm to spare
900mm shower tray — 3 sides: 2 × 900mm + 900mm = 2,700mm — 4.0m provides complete coverage with 1,300mm to spare
P-shaped or L-shaped bath: Measure the full perimeter of sides meeting the wall and add 10% for overlaps
What’s Included
Flexi-Seal flexible rubber waterproofing strip — 4.0m pre-cut
Integrated butyl-based adhesive backing
Installation instructions
How It Works
Prepare: Ensure tray, bath, or worktop edges are clean, dry, and dust-free
Apply: Peel backing and press Flexi-Seal firmly onto the edge using the butyl adhesive
Position: Install the tray, bath, or worktop — the upstand extends up the wall
Tile: Fit tiles or wall panels over the upstand
Seal: Apply neutral cure silicone to the bottom edge once tiling is complete
Suitable For
Large baths — 1700mm and 1800mm standard baths on 3 sides
P-shaped and L-shaped shower baths — extended perimeter coverage
Full-size shower trays — 900mm, 1000mm, 1200mm trays on 3 sides
Extended bathroom worktops and vanity units
New builds where building movement is expected
Bathroom renovations and upgrades
Commercial bathrooms — hotels, gyms, care facilities
Also Available — Waterproofing Strips
Flexi-Seal 2.0m Waterproofing Strip — same product; shorter pre-cut length for compact shower trays, smaller baths, and worktops
Classi Seal 3.2m Waterproofing Strip — alternative brand; self-adhesive membrane; standard 3-sided coverage
Classi Seal Per Metre — cut to your exact length from a 25m roll
Shower Trays — browse compatible flat and low profile trays
Frequently Asked Questions
Will 4.0m cover my bath or shower tray?
Use the coverage guide above to check. For a standard 1700mm bath on 3 sides you need approximately 4.1m — the 4.0m strip provides near-complete coverage with only a small shortfall on the short end (which can be supplemented with an offcut or a short additional piece). For a 1200mm shower tray on 3 sides you need 3.2m, leaving 800mm to spare. For P-shaped or L-shaped baths, measure the full perimeter of the sides meeting the wall and add 10% for overlaps before ordering.
What is the difference between the 4.0m and 2.0m Flexi-Seal?
Both are the same Spajet Flexi-Seal product — flexible rubber, butyl adhesive, BS EN 28510-1 tested. The only difference is the pre-cut length. The 2.0m version is suited to compact shower trays (700–800mm), smaller baths, and worktops. The 4.0m version (this product) is suited to large baths, P-shaped baths, and full-size shower trays where more coverage is needed.
What is the difference between Flexi-Seal and Classi Seal?
Both are professional waterproofing tanking strips but differ in material and adhesive. Flexi-Seal uses a flexible rubber construction with a butyl-based adhesive, tested to BS EN 28510-1 1993. Classi Seal uses a flexible waterproof membrane with a pressure-sensitive self-adhesive backing and accommodates up to 15mm of movement. If you are unsure which is right for your installation, call us on 01603 381095.
Is Flexi-Seal suitable for P-shaped or L-shaped baths?
Yes — the 4.0m length is specifically suited to P-shaped and L-shaped baths where the extended perimeter requires more strip than a standard rectangular bath. Measure the full length of all sides that meet the wall and add 10% for overlaps before ordering to confirm the 4.0m length is sufficient for your specific bath.
What type of silicone should I use at the base edge?
Always use neutral cure silicone (not acetic/vinegar cure). Acetic cure silicone releases acetic acid during curing which can damage rubber and adhesive materials. Neutral cure silicone is widely available and is the correct choice for use with rubber waterproofing strips.
Is Flexi-Seal required if my shower tray has an integrated upstand?
No — if your shower tray has an integrated upstand, the waterproofing is already built into the tray design and a separate seal strip is not required. Check your shower tray specification before ordering. If you are unsure, call us on 01603 381095.
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.
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