At Roundtower Lime, we supply the full range of Delta Membrane Systems – a market-leading, BBA-approved range of Type C cavity drain membranes designed for structural waterproofing, basement conversions, and heritage damp-proofing applications. These membranes are a go-to solution for managing water ingress in new builds, retrofit projects, and historic buildings, offering robust protection while maintaining reversibility and breathability.
Why Choose Delta Membranes?
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BBA-Certified Performance
Certified to British Standards (BS 8102:2009), Delta’s cavity drain membranes are engineered for dependable long-term protection against groundwater ingress and internal damp. -
Reversible and Non-Destructive
Delta systems are non-invasive and fully reversible, making them ideal for use in conservation work or listed buildings where preserving the original structure is essential. -
Flexible and Durable HDPE Membranes
Manufactured from high-quality High-Density Polyethylene (HDPE), Delta membranes are highly resistant to chemicals, rot, and root penetration, while remaining neutral to drinking water.
Delta Membranes Product Range at Roundtower Lime
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Delta MS500 – The standard 8mm stud profile HDPE membrane for internal walls and floors in below-ground environments.
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Delta MS20 – A 20mm stud profile membrane ideal for floor drainage and areas requiring higher drainage capacity.
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Delta PT & Delta PT Slimline – Mesh-faced membranes that support direct plastering or dry lining finishes.
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Delta Qwikseal, FlexiDri, and PT Plugs – Watertight fixing plugs designed to secure membranes and support secondary finishes.
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Delta Tape, Rope, and Corner Strip – Essential sealing accessories for joining and patching membranes while maintaining a full vapour and waterproof barrier.
Applications
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Internal basement waterproofing (walls, floors, and soffits)
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Flood resilience and damp remediation
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Vaulted cellar ceilings and underground structures
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Heritage and listed building refurbishments
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New build basements and extensions
Delta Membrane Systems can be used as part of a sealed sump and pump system or ventilated into the room for moisture management. They are compatible with insulation, dry lining systems, screeds, and plastered finishes depending on the project requirement.
🔍 Frequently Asked Questions (FAQ)
Q1: What is a Type C waterproofing system?
A: Type C waterproofing (as defined in BS 8102:2009) involves a cavity drain system that controls water ingress by collecting and safely channeling it to a drainage outlet. Delta membranes are a leading Type C solution.
Q: Are Delta membranes suitable for listed or historic buildings?
A: Yes. Delta membranes are fully reversible and can be installed without altering or damaging historic fabric, making them ideal for conservation projects.
Q: Can I plaster directly onto Delta membranes?
A: Yes, Delta PT has an integrated mesh that allows lime or gypsum plaster finishes to be applied directly. Other membranes support battened or dot-and-dab systems.
Q: What accessories are required for installation?
A: Fixing plugs (such as Qwikseal or FlexiDri), Delta rope or tape for sealing joints, and Delta Corner Strip for wall-floor junctions are all typically used for a complete system.
Q: Are Delta membranes breathable?
A: Delta membranes do not trap moisture and allow vapour to be managed through drainage or ventilation. They are often used in conjunction with breathable lime plasters or finishes.
