How WDMA Tests Windows and Doors for Strength
In the construction and home improvement industry, the durability and reliability of windows and doors are critical to safety, energy efficiency, and long-term performance. The Window & Door Manufacturers Association (WDMA) plays a leading role in setting the standards that ensure these products can withstand daily use and extreme conditions. But how does WDMA actually test windows and doors for strength?
This article explores the rigorous testing procedures WDMA uses to certify products for structural performance, impact resistance, air and water infiltration, and more.
Why Strength Testing Matters
Windows and doors are exposed to a variety of forces over time, including:
- Wind pressure
- Heavy rain
- Forced entry attempts
- Repeated opening and closing
- Impact from debris or objects
Testing ensures products meet minimum safety and durability standards. WDMA-certified windows and doors are subjected to demanding lab simulations that mimic real-world conditions.
Overview of WDMA Testing Standards
WDMA relies on the North American Fenestration Standard (NAFS), a joint effort with CSA and AAMA, to evaluate structural integrity. Products undergo a battery of tests based on size, materials, and intended use.
Key Strength Tests Include:
- Structural Load Testing
- Forced Entry Resistance Testing
- Impact Resistance Testing
- Air Infiltration Testing
- Water Penetration Resistance Testing
Each test is performed according to strict protocols to ensure accurate, consistent results.
1. Structural Load Testing
This test determines how well a window or door can withstand wind pressure and stress. In a controlled environment, the unit is installed in a testing chamber and exposed to both positive and negative air pressure.
- Positive pressure simulates wind pushing against the window.
- Negative pressure simulates wind pulling from the opposite side.
The product must maintain its shape, seals, and structural integrity during and after the test.
Benefit: Verifies that the unit can hold up during strong storms or high winds.
2. Forced Entry Resistance Testing
For security purposes, windows and doors are tested against break-in scenarios using mechanical tools and force.
- Windows are subjected to prying, lifting, and pushing tests.
- Doors are tested for lock integrity and frame strength.
Benefit: Ensures that products deter unauthorized access and meet security requirements.
3. Impact Resistance Testing
In areas prone to hurricanes or flying debris, impact resistance is vital. WDMA tests simulate objects (like wood or metal projectiles) hitting the glass and frame at high speeds.
- Products are rated for how well they resist shattering or penetration.
- Typically used for coastal or high-risk zones.
Benefit: Confirms protection during severe weather events and enhances occupant safety.
4. Air Infiltration Testing
Air infiltration tests measure how much air passes through a closed window or door at a specific pressure. Less air leakage indicates stronger insulation and performance.
- Results are reported in cubic feet per minute per square foot (cfm/ft²).
- Lower numbers mean better energy efficiency.
Benefit: Helps homeowners reduce heating and cooling costs.
5. Water Penetration Resistance Testing
This test checks how well a product can keep out water during wind-driven rain. Water is sprayed on the exterior while pressure is applied, simulating a storm.
- The product must prevent leaks through seals, frames, and sashes.
- Results determine the window or door’s suitability for different climate zones.
Benefit: Ensures protection against water damage and mold.
WDMA Certification Labels: What They Tell You
WDMA-certified products carry labels that list their Performance Grade (PG), which includes structural, air, and water performance metrics. The higher the PG, the more resilient the window or door is.
Look for the WDMA Windows and Doors certification to verify the product has passed all required strength and performance tests.
Conclusion
The strength of a window or door is more than just a matter of build quality—it’s about verified performance. Through comprehensive lab testing, WDMA ensures products are strong, secure, and suitable for a wide range of climates and conditions. Whether you’re a builder, contractor, or homeowner, choosing WDMA-certified windows and doors offers peace of mind and long-term value.
