Sealing, Tarping, and Structure Preparation
Sealing, Tarping, and Structure Preparation
This domain tests the physical work that keeps gas in the structure: sealing openings, installing and securing tarps, and preparing the building so the dose holds for the required exposure time. Poor sealing is one of the most common causes of failed fumigation and off-site exposure.
Sealing and tarping essentials
- Seal vents, windows, doors, chimneys, fireplace dampers, plumbing penetrations, HVAC openings, dryer vents, and attic fans.
- Use compatible tape, plastic, foam, and sand snakes; secure tarp edges and overlaps so wind cannot lift them.
- Cover or seal roof vents and other openings above the treated space.
- Seal from both inside and outside where access allows; verify each opening is closed before introduction.
- Trim vegetation and remove debris that can puncture the tarp.
- Lock or secure doors, post warning signs, and control access during the entire exposure period.
- Check tarp integrity during introduction and at monitoring intervals.
Worked example
During preparation, a technician finds a fireplace with an open damper and a chimney flue. Reasoning: an open flue is a direct stack for gas loss, so the damper and chimney opening must be sealed with plastic and tape and the fireplace opening covered. If the flue is missed, the structure may not hold concentration, the dose may fail, and gas may escape at the roof. The seal is checked and recorded before the fumigant is introduced.
Traps
- Sealing only from inside and missing roof or exterior openings.
- Using tape that does not adhere to dusty or wet surfaces.
- Forgetting HVAC, dryer vents, and plumbing chases.
- Leaving tarp edges unsecured in wind.
- Failing to recheck seals after tarp installation.
Key points
- Sealing controls both efficacy and off-site risk.
- Fireplaces, chimneys, vents, and HVAC are common leak paths.
- Tarp edges and overlaps must be secured against wind.
- Verify seals before introducing fumigant.
- Control access and post warning signs during exposure.