MC-Bauchemie MC-Flex 1K
A single-component, cold-applied polyurethane liquid membrane that cures with atmospheric moisture into a seamless, crack-bridging waterproof skin.
What is it?
A ready-to-use, single-component polyurethane liquid-applied membrane that reacts with atmospheric moisture to cure into a seamless elastomeric film. No mixing, no heat, no torch.
Where is it used?
Exposed and covered terraces, balconies, podium decks, wet rooms, drainage channels, gutters and planter boxes where a jointless, flexible waterproof layer is needed.
Why use it?
It bridges shrinkage and hairline movement cracks, forms no laps or seams to fail, and installs in coats with a brush, roller or airless spray, making it forgiving on detailing-heavy roofs.
How is it applied?
Prime a sound, dry substrate, then apply in two to three coats at roughly 0.4-0.6 kg/m2 per coat, reinforcing corners and drains, to reach a continuous 1.0-1.5 mm dry film.
About MC-Bauchemie MC-Flex 1K
MC-Flex 1K is a liquid-applied waterproofing membrane built on single-component polyurethane chemistry. It arrives ready to use in a sealed pail, and instead of relying on a second hardener it draws humidity from the air to trigger its cure. As the coats react, the material knits into one continuous elastomeric sheet that follows every contour of the deck, wraps around drains and upstands, and leaves no overlaps or heat-welded joints for water to find later. For teams working on Indian terraces and balconies, where parapet junctions, plumbing penetrations and small level changes cause most leaks, that seamless behaviour is the real selling point.
Because it is cold-applied and needs no torch or open flame, MC-Flex 1K suits occupied buildings, tight rooftops and refurbishment jobs where fire risk and disruption have to stay low. The cured film stays flexible rather than brittle, so it can stretch over the fine cracks that concrete inevitably develops as it dries and moves through the day. Space Arc Engineering supplies and applies this membrane as an authorised distributor and applicator, pairing the material with primers, detailing tapes and protective toppings so the whole system is specified and installed correctly rather than sold as a bare tin.
The technical insight
The performance comes from moisture-triggered polyurethane cure. The resin carries reactive isocyanate groups that stay stable in the sealed container; once the coat is spread thin and exposed to ambient humidity, water vapour reacts with those groups and cross-links the film into a tough, rubbery network. Two consequences matter on site. First, cure depends on air moisture and temperature, so a warm, humid day skins and hardens faster than a cold, dry one, and coats that are laid too thick can trap gas and blister. Second, the finished network is genuinely elastic, with high elongation, so when the concrete below opens a hairline crack the membrane stretches across it instead of tearing. Laying the material in several controlled coats rather than one heavy pour is what delivers both a uniform dry film thickness and a fully reacted, blister-free skin.
Where it is used
- Exposed and screed-protected terrace and flat-roof waterproofing
- Balcony, chajja and podium-deck waterproofing
- Wet areas: bathrooms, toilets, kitchens and utility floors before tiling
- Lining of drainage channels, box gutters and rainwater outlets
- Planter boxes and landscaped roof zones with protection
- Detailing of parapet junctions, upstands and pipe penetrations
- Refurbishment overcoating of sound existing waterproofing where compatible
- Small plant and service-area decks where torch application is unsafe
Key advantages
- Single-component and ready to use, so there is no mixing ratio to get wrong on site
- Cold, torch-free application that is safe for occupied and fire-sensitive buildings
- Seamless, jointless film with no laps or welds to become failure points
- Elastic membrane that bridges shrinkage and hairline movement cracks
- Applies by brush, roller or airless spray, suiting both small details and large areas
- Bonds and self-terminates around drains, upstands and penetrations without accessories
- Fast surface cure lets following coats and light foot traffic resume quickly in good weather
- Backed by Space Arc supply, system detailing and applicator support across India
Limitations & considerations
- Cure depends on ambient moisture and temperature, so cold or very dry conditions slow hardening
- Applying coats too thick can trap curing gas and cause pinholes or blisters
- Needs a sound, dry, properly primed substrate; it will not cure well over damp or contaminated concrete
- Bare single-component PU films can chalk or discolour under prolonged UV unless a UV-stable topcoat or protection is used
- Opened containers begin reacting with air and cannot be reliably stored for later reuse
- Exposed decks with heavy foot or vehicle traffic need a protective screed, tile or wear coat over the membrane
Selection & best practice
Success is decided by preparation and coat control. Start on a structurally sound slab with the correct falls to drains; grind or clean off laitance, curing compounds, oil and loose material, and make sure the surface is dry. Treat cracks and form fillets at wall junctions, then apply the recommended primer. Reinforce all vulnerable details, corners, drains, upstands and pipe collars, with the appropriate detailing before the main coats go down. Apply the membrane in two to three even coats rather than one thick layer, keeping each around 0.4-0.6 kg/m2 and letting each coat cure enough to walk on before the next, so the finished film reaches a continuous 1.0-1.5 mm dry thickness. Watch the weather: avoid application when rain is imminent within the surface-cure window, and where the deck stays exposed to sun and traffic, protect the membrane with a UV-stable topcoat, screed or tiling. Always confirm coverage, coats and cure times against the current manufacturer data sheet for the batch supplied.
Specifications
| Product type | Single-component, moisture-curing polyurethane liquid membrane |
| Components | One-component, ready to use (no on-site mixing) |
| Application method | Brush, roller or airless spray |
| Number of coats | 2 to 3 coats |
| Consumption per coat | Approx. 0.4-0.6 kg/m2 per coat |
| Total dry film thickness | 1.0-1.5 mm (typical) |
| Cure mechanism | Reaction with atmospheric moisture |
| Finished film | Seamless, flexible, crack-bridging elastomeric membrane |
| Recoat / traffic | After surface cure; temperature- and humidity-dependent |
Industry use cases
Residential terraces & balconies
Seamless treatment of housing-society roofs and balconies where parapet junctions and pipe penetrations are the usual leak points, applied cold without disturbing occupants.
Commercial & IT podium decks
Flexible membrane for podiums and plant decks that must bridge concrete movement, later protected with screed or tiling for foot and light service traffic.
Wet-area waterproofing
Sub-tile waterproofing for bathrooms, toilets and kitchens in apartments, hotels and hospitals, forming a jointless barrier around drains and outlets before finishing.
Refurbishment & re-roofing
Torch-free overcoating option for ageing terraces in dense urban plots where flame or hot-work waterproofing is impractical or unsafe.
Drainage & landscaped roofs
Lining of box gutters, channels and planter zones on green-roof and podium-garden projects, where a continuous elastic film resists standing water.
Frequently asked questions
Is MC-Flex 1K a single-component product, or does it need mixing?
How many coats and how much material do I need?
Can it be left exposed to sunlight on an open terrace?
What surfaces does it suit, and how should they be prepared?
Is it safe for occupied buildings?
Does Space Arc only supply the material, or also apply it?
How we position MC-Bauchemie MC-Flex 1K
MC-Flex 1K sits in Space Arc’s liquid-applied polyurethane waterproofing range alongside our other single-component moisture-cured membranes and cementitious systems. Where a project needs a rigid, protective slurry rather than an elastic PU film, our cementitious and acrylic waterproof coatings are the better fit; where heavy movement or below-grade tanking is involved, a heavier PU or PU-modified system should be specified. Buyers comparing brands will also look at Fosroc’s Nitoproof and Brushbond families and Dr. Fixit’s PU membranes for equivalent duty, and our team can specify across all of them so the choice is driven by exposure, traffic and budget rather than a single label.
Fosroc Nitoproof 600 — Specifiers who want a single-component, moisture-curing PU membrane from a widely specified brand, particularly for concealed and below-grade waterproofing, may prefer this Fosroc option.
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Authorised distribution, technical advice & professional application across Delhi NCR and Pan-India.