Flush-Out Guidelines

Flush-Out Guidelines: A Healthy Building from Day One with Source Control, Functioning Ventilation System, and Flush-out


It is important to recognize that the human body is very sensitive to chemical exposures. Choosing lowemission building materials is not enough, but is an important start. TVOC tests can read “0″ while humans occupying the space smell building materials, and bodies can and do react to even low level chemicals. Careful product choices and a 6 to 8 week flush-out with a well-functioning ventilation system work best together to create a healthy building.

Components for opening a healthy new building

  • Source Control: Building materials used are to be low-emission and the least-toxic possible.
  • Flush-out: After finish work is complete and final clean-up is done, conduct a flush-out period of six to eight weeks minimum before classes begin, with ventilation on full, non-porous furniture and equipment in place, cabinets, screens, window shades open for air circulation 24 hours a day.
  • Well-functioning HVAC: Ensure the ventilation system is functioning according to design, and on full throughout the building and for 24 hours a day during the flush-out period. (It is understood here that the design and mechanical systems are functioning as planned, ducts were kept clean throughout construction, any leaks or mould growth have been repaired, the school has been cleaned with leasttoxic cleaning materials, and that any toxic waste will have been appropriately dealt with.)

Flush Out Procedure For New Schools

  1. Remove all porous materials such as furniture, books, paper, fabrics, etc. Otherwise, the chemicals driven off may be absorbed by these materials to be gassed off later, defeating the purpose.
  2. Increase the ventilation throughout the area by turning the in-house ventilation system on high. Additional fans, open windows and doors may help. Include increased exhaust ventilation to the outdoors so as to eliminate the pollution from the area. (Be sure the air intakes, other windows, do not draw the pollution back inside.)
  3. Optional: In new construction, heating up or heating up too quickly can cause uneven drying and cracks or other damage to some new materials. If possible, gradually increase the heat to a maximum of 35 degrees C. Ventilation is more important than heat, but heat will help if it can be achieved. Do not sacrifice the ventilation for heat.
  4. Maintain the flush-out 24 hours a day for as long as possible or necessary – sometimes as long as several months, depending on the materials being off-gassed and the amount being off-gassed. A minimum of six to eight weeks flush-out is recommended for larger buildings such as schools, providing least toxic building materials were used. Gymnasium floors may need additional flush-out.
  5. After a period of primary flush-out, for example, 4 weeks, add the more porous furniture and equipment and materials to the building to be flushed out along with the building.
  6. Computers and other equipment should be on so their operating heat helps gas off their new emissions.
  7. Three days before the end of the flush out period, prior to occupancy, replace filter media with new filters.
  8. After completing the aggressive flush-out, a high ventilation rate should be maintained for at least a year.