Crawl Space Vapor Barrier Installation

Mechanical
Effectiveness:
Cost Level
Medium
Environmental Impact
Low
Resistance Risk
Low
Target Pests
7 species

Target Pests (7)

Common NameScientific NameCategory
Subterranean TermiteReticulitermes flavipesTermites
Carpenter AntCamponotus spp.Ants
MillipedeDiplopodaOccasional Invaders
SowbugOniscus asellusOccasional Invaders
SpringtailsCollembolaOccasional Invaders
SilverfishLepisma saccharinaOccasional Invaders
Fungus GnatSciaridae and MycetophilidaeFlies

Application Method

Install plastic vapor barrier (6-mil or thicker polyethylene sheeting) over exposed soil in crawl space to reduce moisture levels that attract pests and create conducive conditions. Roll out sheeting to cover entire crawl space floor, overlapping seams by 12 inches. Extend sheeting 6 inches up foundation walls and seal edges. Seal around piers and penetrations. Weight or stake sheeting to prevent movement. Vapor barrier reduces soil moisture evaporation into crawl space, lowering humidity that attracts moisture-loving pests and prevents wood decay. Critical component of moisture management reducing conducive conditions for termites, carpenter ants, wood-decay fungi, and moisture pests. Often required for termite warranties.

Timing

Install when excessive crawl space moisture detected or as preventive measure during termite treatment.

Frequency

One-time installation. Inspect annually for tears or displacement. Repair or replace damaged sections as needed.

Preparation Required

Measure crawl space to calculate sheeting needed. Clear debris from crawl space floor. Have 6-mil or heavier plastic sheeting, seam tape, and weights ready. May need to coordinate with general contractor.

Follow-up Required

Monitor crawl space humidity levels to verify reduction. Inspect barrier annually for damage. Explain to customer importance of maintaining barrier. Adjust termite treatment or warranty based on moisture reduction.

Safety Precautions

  • Ensure adequate crawl space ventilation after installation
  • Do not seal ventilation when installing vapor barrier
  • Wear appropriate protective equipment in crawl space
  • Be aware of sharp objects and low clearances
  • May need building permit in some jurisdictions
Important Disclaimer: The information provided in this knowledge base is for educational and reference purposes only. Pest management professionals should always consult current product labels, Safety Data Sheets (SDS), manufacturer instructions, and applicable local, state, and federal regulations as the definitive source of truth. Product formulations, application methods, safety requirements, and regulations may change over time. This information may be out of date and should not replace professional judgment, proper training, or required licensing and certifications.