Mold Containment & Negative-Air Cost Calculator
How much does mold containment cost? Add the poly-barrier area at your rate to the negative-air machine days at your daily rate. Containment is what stops spores spreading, so it deserves its own estimate.
Calculator
A 200 sq ft poly barrier at $1.50/sq ft plus 3 days of negative-air machine rental at $100.00/day is about $660.00. Containment and negative air keep spores from spreading — the day count and airflow are labeled planning typicals a certified technician confirms.
Containment is the quiet half of a mold job. Before a remediator disturbs a single square foot of growth, they seal the work area with poly sheeting and run HEPA negative-air machines so the enclosure stays under slight negative pressure — spores get pulled into the containment and captured, not pushed out into clean rooms. Skip it, and a routine remediation becomes a whole-house contamination.
Because it is often buried inside a lump-sum quote, homeowners rarely see what containment actually costs. This calculator breaks it out: the barrier area at your rate, plus the negative-air days at your daily rate, with a contingency. The counts are labeled planning typicals a certified technician confirms on site.
Formula
Containment has two cost drivers — the physical barrier and the rented negative-air machines that hold the enclosure under negative pressure:
total = (barrier_sqft × price_per_sqft + negative_air_days × price_per_day) × (1 + contingency)
- barrier_sqft — square footage of poly sheeting used to seal the work area (walls, ceiling, zipper-door partitions).
- price_per_sqft — your rate for material and labor to hang the barrier.
- negative_air_days — how many days a HEPA negative-air machine runs to keep spores from escaping.
- price_per_day — the daily rental/operating rate per machine.
- contingency — a buffer for a longer job or extra machines.
The day count and airflow here are labeled planning typicals — a certified technician confirms the real containment plan on site.
Worked example
A single-room containment with 200 sq ft of poly barrier at $1.50/sq ft, 3 days of negative air at $100/day, and a 10% contingency:
- Barrier: 200 × $1.50 = $300
- Negative air: 3 × $100 = $300
- Subtotal: $300 + $300 = $600
- Apply contingency: $600 × 1.10 = $660
The planning estimate is about $660 for containment alone — a cost that is easy to overlook but very real on any job past a small patch.
Sizing containment and negative air
Why containment exists. Mold spreads by spores, and disturbing a colony releases them. A sealed enclosure under negative pressure ensures that airflow moves inward, so spores are drawn to the HEPA machine rather than escaping into living space. It is the single most important step for stopping cross-contamination — and the reason a proper job costs more than a quick surface wipe.
How many machines, how many days. The number of negative-air units and the days they run depend on room volume and the target air-change rate for containment (commonly 4–6 air changes per hour). To size the airflow itself — CFM and unit count from room dimensions — use the air scrubber & negative-air CFM calculator. The day count in this tool is a labeled planning typical; on a real job the technician sets it from the drying and clearance schedule.
Barrier area is more than the wall. Poly is hung not just across the opening but often floor-to-ceiling around the work zone, plus a zipper-door decontamination chamber. Measure the actual sheeting, which is usually larger than the room's footprint suggests.
Containment is part of the whole. On any job past a small patch, fold this figure into the full remediation budget with the mold remediation cost calculator. These are planning typicals from IICRC/AHAM rules of thumb — a certified technician must confirm the containment and drying plan, and health questions are for a physician, not a calculator.
Reference table
Total for your 200 sq ft barrier ($300.00) plus negative air at $100.00/day, by run length (with a 10% contingency):
| Negative-air days | Negative air | Estimated total |
|---|---|---|
| 2 days | $200.00 | $550.00 |
| 3 days | $300.00 | $660.00 |
| 5 days | $500.00 | $880.00 |
| 7 days | $700.00 | $1,100.00 |
Labeled planning typicals — a certified technician confirms the day count on site.