Excess humidity in crawl spaces leads to mold, structural decay, pest attraction, and indoor air quality issues. Spray foam insulation acts as a continuous barrier that seals off moisture intrusion points while maintaining thermal stability. Its closed-cell structure resists water absorption and prevents humid air from entering the subfloor.
In Schertz, TX, where high humidity is common for most of the year, traditional insulation options often degrade or trap moisture. Spray foam’s air-sealing capabilities protect structural integrity and reduce the risk of long-term moisture damage. This article explains how spray foam outperforms alternatives, backed by field data, climate-specific insights, and technical comparisons.
Flatland Roofing & Insulation applies decades of experience in both insulation material science and regional building performance. The information provided reflects first-hand field observations and tested outcomes from crawl space insulation projects across South and Central Texas.
How Spray Foam Works in Crawl Spaces
Closed-cell spray foam is chemically engineered to resist moisture intrusion and maintain high compressive strength. Unlike fiberglass or cellulose, it does not shift or settle. When applied under floors or in wall cavities, it forms an airtight seal that blocks both vapor and air transmission.
Key Functions in High-Humidity Regions Like Schertz:
- Creates an air and moisture barrier
- Inhibits mold growth by eliminating condensation surfaces
- Improves energy efficiency by reducing HVAC workload
- Strengthens subfloor structure with high-density application
Comparative Performance Table
| Insulation Type | Moisture Resistance | Air Sealing | Mold Resistance | Longevity | Application Suitability |
|---|---|---|---|---|---|
| Closed-Cell Spray Foam | High | Excellent | High | 30+ Years | Crawl Spaces |
| Open-Cell Spray Foam | Moderate | Good | Moderate | 15-20 Years | Walls, Attics |
| Fiberglass Batt | Low | Poor | Low | 10-15 Years | Walls, Attics |
| Blown-In Cellulose | Low | Poor | Low | 10-15 Years | Attics, Walls |
Technical Specifications
| Property | Closed-Cell Spray Foam |
|---|---|
| R-Value per Inch | 6.0 to 7.5 |
| Water Absorption Rate | < 1% |
| Air Impermeability | Yes |
| Mold Resistance | High |
| Compressive Strength | 25 psi (ASTM D1621) |
| Vapor Retarder | Class II (1.0 perm or less) |
Regional Climate and Crawl Space Considerations
Schertz experiences high dew points and prolonged humidity from March through October. Subfloor areas without effective sealing act as traps for moisture, leading to microbial growth and wood rot. Ventilated crawl spaces exacerbate this by allowing warm, humid air to meet cooler surfaces, causing condensation.
Spray foam eliminates this by:
- Blocking outside air from entering
- Reducing dew point differences across surfaces
- Preventing temperature-driven moisture migration
Bonus Tip: For existing structures with mold, perform full remediation before applying spray foam. Sealing over active mold colonies can worsen indoor air quality.
Things to Consider Before Making a Decision
- Crawl Space Access: Adequate clearance is required for proper installation.
- Substrate Conditions: Wood and masonry surfaces must be dry and clean.
- Budget Range: Closed-cell spray foam costs more upfront but offers long-term savings on repairs and HVAC use.
- Ventilation Adjustments: Passive vents may need sealing; mechanical dehumidifiers could be necessary depending on the build.
- Code Compliance: Some jurisdictions require ignition barriers over exposed foam in crawl spaces.
Services from Flatland Roofing & Insulation That Address Crawl Space Moisture
- Closed-Cell Spray Foam Insulation: Creates a vapor-tight seal under floors and along walls.
- Insulation Removal: Extracts ineffective or moisture-damaged materials before applying new insulation.
- Blown-In Cellulose: Installed in attic spaces to complement crawl space encapsulation for full-home thermal stability.
- Commercial Insulation Solutions: Applied in buildings where crawl space moisture affects commercial flooring or HVAC systems.
Get Expert Insulation Guidance
Flatland Roofing & Insulation provides technical consultations to assess crawl space conditions in high-humidity zones like Schertz, TX. Recommendations are based on project experience and current building codes. Reach out to evaluate insulation suitability and moisture management needs.
Phone: (806) 606-6794 Email: info@flatlandroofcoatings.com
Common Questions Before Choosing Spray Foam
Do I need to remove existing insulation?
Yes. Fiberglass or cellulose must be removed to allow full bonding of spray foam to joists or subfloor surfaces.
Will spray foam affect pest access?
It can reduce pest entry by sealing gaps, but additional pest control may be necessary in high-infestation zones.
Can I insulate only the floor without walls?
Partial insulation is ineffective in humid crawl spaces. Full encapsulation is recommended.
Is ventilation still needed?
In sealed crawl spaces with foam insulation, mechanical ventilation or dehumidifiers are preferred over passive venting.
Frequently Asked Questions
How long does spray foam insulation last in crawl spaces?
Closed-cell spray foam can remain effective for over 30 years with minimal maintenance.
What is the best R-value for crawl space insulation in Schertz, TX?
R-13 to R-19 is ideal, depending on space depth and HVAC configuration.
How does spray foam handle flood events?
It remains intact and retains insulating value after brief water exposure, unlike fiberglass which must be removed.
Can I apply spray foam myself?
DIY kits exist but are not recommended for crawl spaces due to access difficulty and safety concerns.
What inspections are needed before installation?
Moisture level testing, pest inspection, and structural assessments are advised before spray foam application.