Methyl methacrylate resin is the floor system you specify when downtime cost wins. Two hours from pour to walking traffic. Six hours to forklift traffic. Same-day re-open. The chemistry is fast: an acrylic resin polymerised in place by a benzoyl peroxide catalyst, exothermic, complete in under 60 minutes. The tradeoffs are real: strong odour during install, 30% material premium over PU-cement, certified-applicator required. But for a commercial kitchen that closes at 17:00 and re-opens at 06:00 the next morning, MMA is the only floor system class that fits the operations cycle.
The one-line summary
Fast cure. Industrial-grade. Strong odour. Specify when downtime costs more than 30% material premium over PU-cement — almost always means an operating commercial kitchen, an occupied warehouse on a tight night-shift, or a retrofit where the building cannot close.
Where MMA works · Where it doesn't
Where MMA wins
- Commercial kitchens with overnight shutdown window only (17:00 → 06:00)
- Cold-store and freezer retrofits (only resin that cures at -10°C)
- Hospital operating-theatre re-floor without ward closure
- Active warehouse with night-shift install + morning re-open
- Production-line repair with under-12-hour shutdown
- Concourse + transport infrastructure overnight repair
Where MMA loses
- Occupied buildings without forced ventilation — odour intolerable
- Long-shutdown projects where PU-cement's 40% material discount applies
- Decorative residential — MMA aesthetic is industrial, not designer
- Solvent-sensitive environments (cleanroom, electronic assembly)
- High-UV outdoor without aliphatic topcoat (acrylic yellows)
- Projects with daytime install constraint and no ventilation
Chemistry — how MMA actually cures
Methyl methacrylate monomer + benzoyl peroxide catalyst + amine accelerator. The catalyst initiates free-radical polymerisation; the accelerator drops the activation temperature so the reaction proceeds at ambient temperature. The reaction is exothermic — the freshly-poured surface warms by 10–15°C above ambient during cure, which is why MMA cures at -10°C ambient (the reaction self-heats above freezing).
The cure curve: pot life 15 minutes at 20°C (the working window — applicator must finish trowelling within this), peak exotherm at 30 minutes, walking-traffic at 60–120 minutes, forklift-traffic at 4–6 hours, full chemical resistance at 24 hours.
The trade-off: free MMA monomer has the strong "nail-salon" odour during install. Health-and-safety threshold is well-defined (100 ppm), and forced extraction ventilation keeps the work area within limits. The odour is acute during install + 4 hours post-pour, then dissipates as the resin fully polymerises.
System buildup — typical kitchen 3 mm
| Layer | Material | Thickness | Cure (next layer) |
|---|---|---|---|
| Primer | MMA primer (Sikafloor Pronto-3506) | 0.2–0.3 mm | 30 min |
| Body coat | MMA self-levelling resin (Sikafloor Pronto-PUR Concept or Flowfast) | 2.5–3.5 mm | 30–60 min |
| Broadcast aggregate | Kiln-dried quartz 0.4–0.8 mm (R11 broadcast) | integral | 30 min |
| Sealer / topcoat | MMA sealer (Sikafloor Pronto Top) or aliphatic PU for UV-exposed | 0.3–0.5 mm | 60–120 min walk |
Total cycle from substrate-prep-complete to walking traffic: approximately 6 hours for a small kitchen (50–150 m²). For larger areas, the applicator pours in sections to stay within the 15-minute pot-life window.
Substrate requirements
- CSP 3–5 per ICRI 310.2R-2013 — shot blast preferred, must finish within MMA install window. See ICRI CSP guide.
- Moisture ≤ 4% CM — MMA is less moisture-tolerant than PU-cement; reject wet substrate.
- Substrate temperature minimum -5°C with shielding from direct wind, maximum +25°C.
- Substrate strength minimum 25 MPa cohesive — verify with pull-off test pre-pour. See pull-off test guide.
- Bond coat required over existing coating retained per overlay design.
MMA vs PU-cement — when which
The two-question filter:
- What's your downtime tolerance? Under 12 hours = MMA. 24+ hours = PU-cement OK.
- What's your project area? Under 200 m² = MMA economic. Over 500 m² = PU-cement cost advantage compounds.
For 100 m² commercial kitchen with 12-hour shutdown: MMA every time. The +30% material premium is offset by zero days of operational closure. For 1,500 m² warehouse with weekend availability: PU-cement is the right answer — the cost differential at scale outweighs the modest downtime advantage MMA offers.
Brand + IL channel
- Sika Sikafloor Pronto — the IL default. Routes through Sika's Gilar channel. Certified applicators required for warranty.
- Flowcrete Flowfast — UK-origin MMA system, Mapei sister brand after 2018 acquisition. IL availability via Mapei channel. See Flowcrete brand profile.
- BASF / MBS — discontinued IL line — historically present, now phased out post-Sika MBCC acquisition (May 2023). MasterTop fast-cure now rebrands as Sika.
Common MMA mistakes
- Pour without forced ventilation in an occupied building. Odour reaches intolerable level within 30 minutes; occupants evacuate.
- Pot-life overrun. 15-minute window is hard — applicator pours more than they can trowel within window. The over-poured area sets unworkably and creates surface defects.
- Substrate temperature outside -25 to +35°C. Below -25°C the reaction is too slow; above +35°C pot life collapses to under 5 minutes.
- Underspecified ventilation. Calculation should target 100 ppm MMA monomer in work zone at peak exotherm — typically 2× the rate applicators initially specify.
- MMA over fresh concrete (< 14 days). Substrate moisture causes bond failure. Wait minimum 21 days cure on new slab.
Care and maintenance
MMA care is essentially the same as PU-cement: daily auto-scrubber with alkali-tolerant cleaner, periodic R-class verification at high-traffic zones. See floor care by system type §4 (epoxy + quartz + PU spec) — care protocols are interchangeable.
Final read
MMA is downtime-cost economics in resin form. The chemistry trades health-and-safety overhead for operational continuity. For the right project — a 100 m² restaurant kitchen on a 12-hour shutdown — MMA is the only system class that delivers a usable floor by morning service. Specify when downtime cost dominates; specify PU-cement when material cost dominates. Related: PU-cement encyclopedia · epoxy SL encyclopedia · resin family comparison · selection by use case.
Sources
- Sika Sikafloor Pronto family product data sheets (Pronto-3506 primer, Pronto-PUR Concept body coat, Pronto Top sealer).
- Flowcrete Flowfast product data sheets.
- EN 13813 — Synthetic resin screeds standard (MMA classification).
- DIN 51130 R-class slip testing methodology.
- ICRI 310.2R-2013 substrate preparation.
- Floor.DSGN IL contractor field data — 30+ MMA installations.