Water in your basement is not just a nuisance — it is structural damage in slow motion.
When excavation is not an option, an interior waterproofing system is the professional answer. MPM STARFLEX liquid membranes seal walls and floors from inside — even on wet or damp concrete — without disrupting the perimeter or halting operations.
Over 70 years of Italian chemical expertise. Certified durability up to 30 years.
On this page:
What is an interior waterproofing system — and when do you need one?
An interior waterproofing system is a solution applied from inside a building to stop water from penetrating through basement walls, floors, or underground structures. The membrane is applied to the internal face of the structure: no excavation, no disruption to the perimeter.
It is the right choice when:
- the building is already standing and external excavation is prohibitively expensive or disruptive
- the project is a renovation or retrofit of an existing basement
- urban density, adjacent structures, or active infrastructure make exterior access impractical
- speed of execution is critical and downtime must be minimised
Interior waterproofing does not replace exterior waterproofing where that is feasible. It is the professional’s answer when it is not.
Hydrostatic pressure: the main cause of basement water infiltration
Groundwater does not wait for cracks to appear — it creates them. As water accumulates around a foundation, it builds hydrostatic pressure that forces its way through any imperfection in concrete: a hairline crack, a construction joint, a pipe penetration. Over time, the result is water ingress, reinforcement corrosion, spalling, and mould.
A correctly specified interior waterproofing system is the first line of defence. The membrane must resist water pressure from the negative side — from within — which demands specific chemistry and adhesion performance that standard coatings do not provide.
Interior waterproofing products: the STARFLEX range
Not every waterproofing membrane performs from the inside. Interior applications present conditions that external systems are not designed for: water pressure acting in reverse, limited airflow during curing, substrates that are rarely dry. Every product in the STARFLEX range addresses these constraints directly.
Starflex HYBRID
Liquid membrane for wet basement walls
When the substrate is wet and there is no time to wait, STARFLEX HYBRID is the answer. This single-component aliphatic polymeric membrane bonds directly on wet or damp concrete in some cases also without a primer. Rapid cure even at low temperatures, outstanding elasticity and adhesion — the complete package for interior retrofit projects where site conditions are never ideal.
Starflex H-ZERO
Polyurethane waterproofing membrane for interior use
Single-component polyurethane-based membranes for seamless interior waterproofing with strong adhesion to concrete, bituminous sheaths, PVC, tiles, and metal. High elasticity for structures subject to thermal movement or minor settling. H-ZERO is the non-ADR variant — safer for transport and application in confined interior spaces.
Starflex C
Cementitious waterproofing for basement walls and pools
When a mineral-based interior waterproofing system is preferred — for compatibility, regulatory, or substrate reasons — STARFLEX C delivers. This bi-component elastic cementitious mortar cures on damp or cold surfaces, bridges cracks, and bonds firmly to concrete and masonry. Ideal for swimming pools, water tanks, and basement walls with constant water exposure.
Starflex ULTRA (FR)
Polyurea waterproofing system for underground structures
Certified durability up to 30 years. Wet-on-wet application. Rain-safe after 1 hour. Fire-certified B-roof T4. STARFLEX ULTRA is the benchmark product for underground structures and foundations that demand maximum long-term reliability — the interior waterproofing system where failure is not an option.
Starflex ONE
Waterproof coating for basement concrete repair and maintenance
STARFLEX ONE is a single-component elastic bituminous water-based membrane built for high adhesion even on wet or irregular concrete. UV-resistant, extremely flexible, easy to apply — a practical, cost-effective solution for basement maintenance and restoration projects.
| Product | Applies on wet substrate? | Key advantage | Best for |
| STARFLEX HYBRID | Yes — even with no primer | Bonds on wet concrete, rapid cure | Retrofit, difficult site conditions |
| STARFLEX ONE | Yes if humid | Easy application, UV-resistant | Maintenance and restoration |
| STARFLEX C | Yes — cures on damp surfaces | Cementitious, crack-bridging | Pools, tanks, masonry basements |
| STARFLEX H-ZERO | Yes | High elasticity, multi-substrate | Moving structures, confined spaces |
| STARFLEX ULTRA (FR) | No | 30-year certified durability | Critical underground structures |
It bonds on wet concrete — where most products fail
Interior waterproofing often means working in a damp, poorly ventilated basement — exactly the conditions that compromise standard coatings. STARFLEX HYBRID and STARFLEX ONE are specifically formulated to maintain full adhesion and performance on wet substrates.
Seamless liquid membrane: no joints, no weak points
A liquid-applied interior waterproofing membrane conforms to every surface it touches: corners, pipe penetrations, irregular walls, construction joints. There are no laps, no overlaps, no seams where water finds a path through.
Certified performance: up to 30 years of documented durability
Certified durability up to 30 years. Independent testing to ETAG 005, CE 1504, CAM, BBA, and Broof T4. More than 100 international certifications across the STARFLEX range. When an engineer or building inspector asks for proof, MPM provides documentation — not reassurances.
Made in Italy — 70 years of applied chemistry, training and support included
MPM has been developing protective chemistry for construction since the 1950s. Five R&D laboratories, over 40 certified products, production capacity exceeding 50,000 kg per day. Every STARFLEX membrane is manufactured in Italy — and the expertise comes with the product: training programmes, site visits, specification guidelines, and ongoing support from the technical team that knows these systems from the inside out.
→ Become a STARFLEX distributor: talk to our tech team
→ Talk to our technical team
Interior waterproofing system: application fields
Any below-grade or internal surface exposed to water pressure, ground moisture, or sustained humidity is a candidate for STARFLEX interior waterproofing. These are the most common applications.
Waterproofing an existing basement from inside
The most frequent application. Excavating around a standing building to waterproof from outside is expensive, disruptive, and often impossible in urban environments. Applying a STARFLEX system from inside stops infiltration without touching the perimeter — restoring the usability of the space with minimal disruption to the building or its occupants.
Foundation and retaining wall waterproofing — interior application
Foundations face constant attack from ground moisture and hydrostatic pressure. Where the external face is inaccessible, an interior waterproofing membrane applied to the internal surface stops the ingress pathway — preventing reinforcement corrosion and the slow-motion structural damage that follows unchecked infiltration.
Underground car park and trafficked slab waterproofing
Below-grade parking structures face water infiltration, chloride ingress from de-icing salts, and heavy mechanical load. STARFLEX HR-M — a self-levelling bi-component polyurea membrane with pedestrian and vehicle load resistance — provides combined structural and waterproofing protection for these demanding environments.
Swimming pools, water tanks, and water retention structures
Constant water contact, chemical exposure, and the need for a permanently watertight finish make interior waterproofing essential for pools, water tanks, and treatment basins. STARFLEX C deliver the chemical resistance and permanent adhesion these applications demand.
Tunnels, underpasses, and underground infrastructure
Structural movement, constant humidity, and sustained hydrostatic pressure define tunnel environments. MPM’s liquid membranes adapt to complex geometries without joints, providing long-term protection for infrastructure assets where maintenance access is infrequent and failure is costly.
Industrial facilities: pits, tanks, and buried structures
Underground service pits, inspection channels, buried process tanks, and technical basements in industrial plants need protection against both water and chemical aggression. STARFLEX products are selected according to the chemical agents present — delivering combined waterproofing and chemical resistance in a single system.
Common questions about interior waterproofing
Can I apply an interior waterproofing system to an already-wet basement?
Yes. STARFLEX HYBRID and STARFLEX ONE bond directly on damp or wet substrates — the condition found in most retrofit projects. Active leaks should be stopped with injection mortar before membrane application, but the presence of surface moisture alone does not prevent application.
How long does an interior waterproofing system last?
STARFLEX ULTRA FR carries certified durability of up to 30 years. All products in the range are designed for long-term performance, combining high elasticity, crack-bridging, and resistance to sustained water pressure. Actual service life depends on correct application and substrate condition.
Does interior waterproofing work against hydrostatic pressure?
Yes. STARFLEX polymer and cementitious systems both resist sustained negative-side water pressure. Product selection and application thickness are matched to the pressure level expected for each project.
Do I need a professional applicator for STARFLEX systems?
For guaranteed performance and warranty coverage, yes. MPM trains and certifies applicators and supports projects from specification to completion. Using a trained applicator is the difference between a system that lasts 30 years and one that fails in 3.
Stop water infiltration before it becomes structural damage
Water damage does not announce itself. An interior waterproofing system applied now costs a fraction of structural repair later.
MPM’s technical team will assess your project, identify the right STARFLEX system, and support the entire process — from specification through to completed application.
Contact us for support and offers
MIXER SRL – mpm division
Via Adda 15, 20073 Opera (MI) – Italy
Email: info@mpmsrl.com
Privacy & Cookie Policy
Contacts
Ph. +39 02 57609116 – +39 02 57601225
Fax +39 02 57603410
REA: MI – 1797438 – VAT N.: 09351720157
