What you are smelling
An MMA floor is mixed on site from liquid methyl methacrylate. While each coat is wet, some of that liquid evaporates. NIOSH describes the odor as acrid and fruity. One flooring maker compares it to Super Glue.
People notice it at very low levels. An EPA hazard summary puts the odor threshold at 0.08 parts per million. The OSHA limit for workers is 100 ppm averaged over a shift, and OSHA's chemical data page also lists a stricter 50 ppm figure from ACGIH. So a nose picks up MMA at roughly a thousandth of the OSHA limit. That is why people well away from the work can smell it, and why smell alone does not tell you how much is in the air.
It is still a chemical to respect. NIOSH lists irritation of the eyes, skin, nose and throat. EPA adds headache and lightheadedness after short exposures. The liquid is also flammable, with a flash point of 50°F.
How installers ventilate
The published approach has two halves. Keep the vapor inside the work area, and move it outdoors.
A Construction Canada article describes the usual setup. The crew builds a barrier around the work area and seals the HVAC return vents, then runs fans and filters. For a 5,400 square foot cafeteria it estimates about half a shift to set that up. Sika's MMA primer sheet puts a number on the airflow: at least seven air changes per hour, using forced fresh air and exhaust.
The equipment matters. Sika's data sheets require explosion-safe ventilation and ban smoking, open flames and sparks while the liquid is handled. In a kitchen, ask what happens to the pilot lights. Airflow is also part of the cure. The same sheets make fans mandatory wherever air is restricted.
An old MIT facilities notice shows a careful plan for an occupied campus. It covers a Silikal floor in 2000. The notice does not name the resin, only a strong odor that fades as the floor cures. The contractor was to seal the area and keep it under negative pressure with four ventilation units exhausting outdoors. Work was set for weekend evenings in an empty building. Air intake fans on neighboring buildings were to be shut off during the work, and people nearby were advised to close their windows.
Food plants and kitchens
Treat this as a food safety question, not a comfort one. Sika's MMA sheets say all foodstuffs must be removed during installation. The primer sheet goes further: any food, packaged or not, is to be kept completely isolated until the floor is fully cured. A Food Manufacture article quoting a UK flooring supplier makes the same case. The risk of tainting food runs from mixing until the cure is complete, and production in that area should stop until then.
Plan where ingredients and finished product will go, and for how long. Bring in whoever runs your food safety plan before the dates are set. For the cured floor, ask for the product's food-contact paperwork. Sika lists an NSF registration for incidental food contact on one MMA top coat sheet.
How long it lasts
Each coat cures fast. Sika lists 35 to 60 minutes at 75°F for its primer, and says a freezer system may take longer than an hour below freezing. Flowcrete advertises 60 minutes for its MMA range and lists two hours for its trowelled quartz floors. But a floor is several coats, one after another, so the smell is produced for as long as the crew is working.
After the last coat cures, the sources agree that it fades quickly. Sika says its systems are odor free once fully cured. Sherwin-Williams still advises setting aside time after the work for the remaining vapor to clear before the space is used again and goods come back in. None of them gives a number of hours. Ask your installer for one, in writing.
What to ask the installer
- Where will the exhaust come out, and what is near that spot?
- Which HVAC zones get shut down or sealed, and who does it?
- Is the ventilation equipment rated for flammable vapor?
- When can people come back in? When can food come back?
If you share a building, tell the landlord and the other tenants before the work starts.
Sources
- NIOSH Pocket Guide to Chemical Hazards: Methyl methacrylate
- OSHA Occupational Chemical Database: Methyl methacrylate
- U.S. EPA, Methyl Methacrylate hazard summary
- Sika, Sikafloor-13 Pronto MMA primer data sheet (2020)
- Sika, Sikafloor-71 TC Pronto MMA top coat data sheet (2026)
- Sika, Sikafloor Pronto RB-1823 CQ system data sheet (2025)
- Sherwin-Williams, Acrydur MMA floor systems brochure
- Flowcrete UK, Flowfast MMA flooring flyer (2019)
- Construction Canada, Enabling faster returns to service when installing flooring (2017)
- Food Manufacture, Taint-free flooring claims disputed (2006)
- MIT Department of Facilities, Building 33 flooring notice (2000)
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