How to Install HydraFlex – Flexible Tanking Membrane

Installation overview — flexible tanking for walls & floors (illustration only)

1. What is HydraFlex?

HydraFlex is a flexible, polymer-modified waterproofing membrane designed to form a continuous barrier (Type A protection) against moisture and water ingress on masonry and concrete. Its flexibility helps accommodate minor movement and hairline cracking, making it suitable for below-ground walls, wet areas, service rooms and floor slabs.

2. Suitable substrates & areas

• Concrete, blockwork, brickwork and sound render/screed.
• Internal faces of basements, cellars and retaining structures.
• Wet rooms, plant rooms, service risers and floor slabs (as specified).
• Not suitable over weak, friable, dusty or contaminated surfaces without prior preparation.

3. Safety & preparation

• PPE: Gloves, eye protection and a suitable mask/respirator when mixing, cutting or grinding.
• Defects first: Repair cracks, blow-holes and honeycombing. Stop active leaks with a rapid-setting plugging compound.
• Surface prep: Remove paint, oils, laitance and loose material. Mechanically prepare to a clean, open-pore finish.
• Fillets: Form concave cementitious fillets at wall–floor junctions and internal corners to reduce stress.
• Conditioning: Lightly dampen absorbent substrates (SSD) if the data sheet permits—no standing water.

4. Tools & materials

• HydraFlex flexible tanking membrane (as specified)
• Compatible primer/bond coat (if required)
• Cementitious repair mortar & rapid-setting plug (prep/fillets/leaks)
• Brush/roller/trowel or spray equipment; mixing paddle and bucket
• Reinforcing mesh/band for changes of plane and local crack bridging (if specified)
• Protection/drainage board for backfilled areas

5. Priming & junctions

• Prime substrates where required to control suction and improve adhesion.
• Form fillets (typically 25–40 mm radius) at internal corners and wall–floor junctions.
• Detail penetrations (pipes, bolts) with sleeves/sealants to allow a continuous membrane.

6. First coat application

1. Apply the first coat by brush, roller, trowel or spray per the product guidance.
2. Work firmly into pores/pinholes to ensure full contact and even coverage.
3. Observe the specified wet-film thickness; avoid thin or translucent areas.

7. Reinforcement & crack bridging

• While the first coat is fresh (or as directed), embed reinforcing mesh/band at internal corners, changes of plane, around penetrations and across hairline cracks.
• Ensure overlaps of reinforcement meet or exceed the system minimum.

8. Second coat application

1. Allow the first coat to reach initial cure (finger-firm) based on site conditions.
2. Apply the second coat at 90° to the first (cross-hatch) for uniformity and continuity.
3. Extend coating beyond visibly damp zones onto sound substrate for a robust lap.

9. Floors & wall–floor junctions

• Prepare slabs as per walls; remove weak laitance and contaminants.
• Coat floors continuously and up the wall onto the fillet to create a tanked tray.
• Protect coated floors from early traffic; follow cure times before screeds/finishes.

10. Curing, protection & finishing

• Protect fresh coats from rapid drying, frost, direct rain/water impact and abrasion.
• Respect cure times before applying renders, insulation boards, tiles or other finishes.
• Use compatible breathable finishes where required; avoid solvent-based products directly on the membrane unless approved.

11. Integration with other systems

• For higher-risk basements, combine HydraFlex (Type A) with a Type C drained cavity system (stud membranes, perimeter channels, sump & pump) to improve resilience and serviceability.
• Ensure clean transitions to membranes, terminations into chases, and sealed laps at thresholds/columns/steps.

12. Quality checks & common pitfalls

• Pinhole/holiday risk: Inadequate prep or thin application—re-coat locally to reinstate continuity.
• Poor adhesion: Occurs on dusty, painted or contaminated substrates—mechanical prep is essential.
• Junction failures: Omitting fillets or reinforcement at changes of plane—always detail critical junctions.

13. Product availability

All components for this system—HydraFlex flexible tanking membrane, primers, cementitious repair/fillet mortars, reinforcement bands/mesh, protection boards, plus complementary cavity drain membranes, channels and sump & pump kits—are available directly from Clever Shield Coatings. Use the website search bar or browse our product categories to find what you need.