MC-Bauchemie MC-Plan 120 IN
A 2mm loose-laid PVC membrane that welds into a single watertight envelope around basements, tunnels and water-retaining structures.
What is it?
A non-reinforced, 2mm flexible PVC waterproofing sheet in dual-tone rolls — light top signal colour over a dark base — laid loose and hot-air welded at every joint rather than bonded down.
Where is it used?
Below-grade basements and raft slabs, underground reservoirs and canals, cut-and-cover metro/road tunnel linings, and terrace gardens or podium decks needing root-resistant waterproofing.
Why use it?
Unbonded to the concrete, it rides out shrinkage cracking and joint movement without tearing, while continuous welding creates one seamless, compartmentalised skin that individual leak zones can be repaired in later — without breaking the slab.
How is it applied?
Rolled out loose over a clean, sound substrate (geotextile first if sharp projections exist), overlapped to spec, and every seam fused with a calibrated hot-air or hot-wedge welder, checked manually for water-tightness before backfilling.
About MC-Bauchemie MC-Plan 120 IN
MC-Plan 120 IN is MC-Bauchemie India’s loose-laid PVC membrane in the MC-Plan waterproofing range, alongside the pre-applied MC-Plan 312 PA-IN and MC-Plan 315 PA-IN from the same Navi Mumbai manufacturer. Where the PA-IN membranes bond directly to freshly poured concrete, MC-Plan 120 IN takes the more forgiving route: the 2mm PVC sheet is laid loose across the substrate — over blinding concrete, retaining walls or tunnel formwork — and every overlap is fused shut with a hot-air or hot-wedge welder. The result is a continuous membrane that behaves independently of whatever the concrete around it does afterwards, which matters on tunnel boxes, deep basements and water tanks where shrinkage cracking is hard to rule out.
The datasheet backs this with numbers a consultant actually checks: 5 bar hydrostatic pressure resistance held for 24 hours, welded-seam shear strength of ≥13.5 N/mm² to EN 12317-2, and EN 14416 root-resistance certification that lets the same sheet double up under a terrace garden. What it won’t do is sit exposed to sun for years — like most unreinforced PVC, UV degrades the plasticiser over time, so MC-Bauchemie is explicit that exposed use needs a protective screed or growing medium over it. On a Space Arc site we treat this as a specialist-applicator product: the sheet is simple, but the waterproofing only performs as tested if the welding crew is trained and every seam checked before it’s buried.
The technical insight
The real design choice is bonded versus loose-laid. Pre-applied membranes (MC-Bauchemie’s own PA-IN range) key directly into the pour, resisting lateral water migration if breached — but repair usually means breaking into the structure. MC-Plan 120 IN’s loose-laid, welded approach trades some of that resistance for repairability: an unbonded compartment that leaks can, in principle, be isolated and re-welded from within, without demolishing the slab above — why loose-laid PVC remains a default for metro cut-and-cover boxes and large tanks with 50-year-plus service lives. The dual-colour layer isn’t cosmetic either: it’s a QA feature, exposing the contrasting under-colour the moment a puncture occurs.
Where it is used
- Loose-laid waterproofing beneath basement raft slabs and behind retaining walls
- Underground water-retaining structures — service reservoirs, tanks and lined canals
- Waterproofing lining for cut-and-cover metro and road tunnel box structures
- Terrace gardens and podium decks, using the EN 14416 root-resistance rating
- Basement lift pits and sumps under sustained hydrostatic head
- Substructures in saline, sulphate- or chloride-contaminated ground
- Blind-side waterproofing over shuttering or lean-concrete blinding ahead of a pour
Key advantages
- Continuous, hot-air-welded envelope with no bonding-layer pinholes to chase
- Loose-laid, compartmentalised system — a leak zone can be isolated and repaired without breaking open the slab
- Holds 5 bar hydrostatic pressure for 24 hours — suited to deep, below-water-table basements
- EN 14416 root-resistance rating lets it double as waterproofing under terrace gardens and podiums
- Welded-seam shear strength ≥13.5 N/mm² (EN 12317-2) keeps the joint from being the weak point
- Good resistance to ground salts, chlorides and sulphates on contaminated or saline sites
- Not rigidly bonded, so it tolerates substrate undulation and joint movement without tearing
- Twin-colour signal layer makes punctures and weld defects visible on site
Limitations & considerations
- Not UV-stable long-term — exposed roofs, terraces or walls need a protective screed or paver bed over it
- Performance is largely weld-quality dependent; needs a trained crew and calibrated welding equipment, not a DIY sheet
- Being loose-laid, it needs proper confinement above and below or the sheet can shift during the concrete pour
- Unreinforced 2mm PVC can be punctured by sharp aggregate or rebar unless a geotextile layer is used first
- Lower puncture tolerance than fibre-reinforced or thicker HDPE systems on very aggressive, rocky substrates
- A preventive, new-build system — not a remedial fix for an already-leaking structure without excavation
Selection & best practice
Treat substrate prep as seriously as the membrane: it must be sound, free of standing water, sharp projections and chemical contamination, with a 200/300 GSM geotextile laid first over any blinding concrete likely to have laitance ridges or exposed aggregate. Maintain the specified overlap on every joint and weld with a calibrated hot-air or hot-wedge machine — temperature and speed both affect seam strength, so pull-test welds routinely and run needle or vacuum testing where specified, before any joint is covered. Sequence the pour so the waterproofing gang is signed off before reinforcement fixing starts on top, and detail the protective screed for any exposed area before handover, not as an afterthought.
Specifications
| Type | Non-reinforced, flexible PVC (polyvinyl chloride) membrane, loose-laid and hot-air welded |
| Thickness | 2 mm ±10% (EN 1849-2) |
| Specific weight | 2.6 kg/m² ±5% (EN 1849-2) |
| Tensile strength | ≥17 N/mm² longitudinal & transverse (EN 12311-1) |
| Elongation at failure | ≥300% longitudinal & transverse (EN 12311-1) |
| Water pressure resistance | 5 bar, watertight for 24 hours |
| Welded-seam shear strength | ≥13.5 N/mm² (EN 12317-2) |
| Static puncture resistance | ≥20 kg for 24 hours (EN 12730-B) |
| Pack size | Roll, 2 m x 20 m (40 m² per roll) |
Industry use cases
Metro & Tunnel Infrastructure
Loose-laid, welded lining for cut-and-cover box structures, where compartmentalised repair matters over a decades-long asset life.
Water & Irrigation
Underground reservoirs, effluent tanks and canal linings needing sustained hydrostatic-pressure resistance.
Deep Basements
Multi-level basement rafts and walls below the water table, tolerant of construction-joint movement.
Green Roofs & Podium Decks
Terrace gardens and landscaped podiums, protected by the EN 14416 root-resistance rating.
Industrial STP/WTP
Below-grade treatment tanks and pits exposed to saline or chemically contaminated ground.
Frequently asked questions
Is MC-Plan 120 IN bonded to the concrete, or does it sit loose?
Can we leave it exposed on a terrace without any covering?
What roll size does it come in, and how much overlap should we allow?
How do you verify the welds are actually watertight?
Does it need a protection layer under it, too?
Does Space Arc supply the welding crew, or just the material?
How we position MC-Bauchemie MC-Plan 120 IN
Within MC-Bauchemie’s own India range, MC-Plan 120 IN is the loose-laid option; where a project wants the sheet bonded into the pour instead, MC-Plan 312 PA-IN and MC-Plan 315 PA-IN are the pre-applied alternatives from the same manufacturer. Outside the brand, the closest genuine equivalent is Fosroc’s Proofex Alkorplan 35041 — also a loose-laid, hot-air-welded PVC membrane with a damage-indicating signal layer — often specified when a project has standardised on Fosroc elsewhere. Sika’s Sikaplan range covers similar territory in the wider market too, though it isn’t currently part of Space Arc’s supply chain.
Fosroc Proofex Alkorplan 35041 — Also a loose-laid, hot-air-welded PVC membrane with a damage-indicating signal layer, often specified when a project has already standardised on Fosroc elsewhere or has an approved Fosroc method statement for tunnel and metro work.
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