Is PVC coated fabric waterproof?

Here's an explanation of the waterproof properties of PVC-coated fabric:

1. A sealed plastic film prevents leaks.

 The surface PVC layer is key to waterproofing: Imagine a tightly sealed plastic film (similar to a thick raincoat) on the fabric; water splashed on it will simply slide off and won't penetrate.
An intact coating equals absolute waterproofing: As long as the PVC layer is intact, it will block rain, splashes, and snowmelt, just like water in a plastic bucket.

2. Seams and edges determine the actual effect.

 The fabric itself is waterproof, but the seams are a weakness: micropores left by stitches can leak, like water seeping through the sewn edges of an umbrella.
Good products reinforce the edges: High-quality PVC-coated fabric uses heat-sealed edges or waterproof tape to cover the seams (like the seams of a truck tarpaulin) to seal leaks.

3. These situations can cause waterproofing to fail:

Scratches and wear: Tear by branches, repeated folding and abrasion, exposing the underlying fabric, allows water to seep in through the opening.
Aging and Cracking: After prolonged exposure to sunlight or cold winters, PVC becomes brittle and cracks fine lines (like cracks in an old plastic basin), leading to leaks.
Inferior Coating or Processing: A thin coating is prone to perforation; edges are only stitched with ordinary thread without sealing—potentially causing leaks from the start.

4. How to Choose Truly Waterproof PVC Coated Fabric?

Feel the Thickness: The thicker the surface PVC layer (feeling like a car tarpaulin), the more durable and waterproof it is.
Check the Seams: Edges with heat-sealed strips or heat-fused edges (no loose threads or needle holes) are more reliable in terms of waterproofing.
Test the Elasticity: If it quickly recovers its flatness without cracks after being rubbed, the coating is flexible and not easily cracked.

■ Common Uses to Verify Waterproofing

Completely Waterproof: Truck tarpaulins, large water tank linings, outdoor tent tops—these require a thick PVC coating and sealing process.
Potentially Leaking: Cheap storage bags, thin picnic mats—thin PVC layers or poor stitching provide short-term water repellency but easily fail over time.